Effects of Fasting & Time Restricted Eating on Fat Loss & Health | Huberman Lab Podcast #41

- Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman and I'm a professor of Neurobiology and Ophthalmology at Stanford School of Medicine. Today we will talk all about

fasting

. And every

time

we talk about

fasting

, we also talk about

eating

, because we all need to eat sooner or later. We are going to talk about how fasting and when we eat influences a wide variety of aspects of our

health

and well-being, both physical and mental. So, well, nowadays, most people are familiar with the term intermittent fasting, also some

time

s called time-

restricted

eating

.

I think most people don't really understand how that process works. It's pretty obvious that intermittent fasting, also known as time-

restricted

eating, involves eating at certain periods of each 24-hour cycle, or maybe even not eating for entire days, in some cases. But, if you think about it, in the end everyone sleeps. And therefore, because people don't eat while they sleep, almost everyone employs some form of intermittent fasting or time-restricted eating. What we are going to talk about today is how certain eating schedules with time restrictions can affect our

health

in different ways. And when I say different ways, I mean, we're going to talk about how intermittent fasting, also known as time-restricted eating, impacts weight

loss

, particularly fat

loss

, muscle maintenance, and loss and gain, the health of organs, such as the intestine. liver health and health, genome, epigenome, inflammation, disease, disease recovery and healing, exercise, cognition, mood and life expectancy.

So we're going to cover a huge amount of information. I promise to make everything directly accessible, regardless of whether or not you have a background in biology and metabolic science. I'm also going to talk about many tools. In fact, I'm going to discuss a number of tools during today's episode that actually make it so that you don't have to follow any eating or fasting schedule, the same if you think about it, in any absolutely strict regimen. This way, that is, if you only ate during an eight-hour period of each day, most of the time, but then ate occasionally during a 12-hour period of the day, in theory, that could have detrimental health

effects

. quite serious.

And yet, there are things you can do to mitigate those negative

effects

. In fact, there are things you can do or take that can make it feel like you haven't eaten at all. Then we will discuss what those tools are. And in many cases, for health, weight loss, and performance reasons, making your body think you didn't eat anything can be quite beneficial. So today we will cover the mechanism and tools. Before we do that, I want to highlight one particular result that was recently published, because it serves as a useful backbone as we delve into the conversation about fasting.

This is a study that was published in the journal Cell Metabolism: A Cell Press Journal, an excellent journal. And the title of the article is "Fasting Blood Glucose as a Predictor of Mortality: Lost in Translation." And I'll explain what the "Lost in Translation" part means in a moment. But the basic conclusion of this study, and I should mention that the first author of the study is Palliyaguru, PALLIYAGURU, guru, Palliyaguru, et al. The basic finding of the study is that in humans, higher blood glucose is associated with mortality. And in fact, if we look at blood glucose, resting blood glucose across the lifespan, what we find is that as people get older, resting blood glucose increases.

Now this is very interesting, because for a long time it was thought that metabolism actually decreases as we age. And to some extent, that's true, but reductions in metabolism aren't as robust as we once thought they were across the lifespan. However, unless something is done to mitigate the rise in blood glucose associated with aging, almost everyone experiences a gradual but regular rise in resting blood glucose that predicts mortality. Now, the title, as I mentioned, is "Fasting Blood Glucose as a Predictor of Mortality: Lost in Translation." And the reason they included "Lost in Translation" in the title is that what I just told you, that increases in resting blood glucose predict mortality, or correlate with mortality, is true for humans and for non-human primates, monkeys. .

But the opposite happens in mice. That's why I thought it was important to use this study as an example of how studies in mice often, but not always, translate to humans and non-human primates. So today I'm going to be careful to distinguish when a study was done in mice versus humans, because it seems that at least when talking about diet, blood glucose, and other aspects of diet related to health and well-being, whether o The fact that no studies have been carried out in rodents or humans may be very important. In this case, the results were directly opposite each other by 180 degrees.

In other words, in mice, resting blood glucose decreased and was associated with mortality. Therefore, lower blood glucose is associated with mortality. While in humans, a higher resting blood glucose level was associated with mortality. And obviously, what interests us most is the health and well-being of ourselves, of humans. I'm sure there are some people who are intensely concerned about the health and well-being of mice, and you can imagine some weird contexts in which that is important, but obviously most of us are interested in human health. So I'll be sure to emphasize when studies were done in humans versus mice.

Before we begin, I would like to emphasize that this

podcast

is independent of my teaching and research duties at Stanford. However, it is part of my desire and effort to bring zero-cost information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's

podcast

. Our first sponsor is ROKA. ROKA manufactures the highest quality eyeglasses and sunglasses. I've spent my entire life working on the visual system and how we see, and ROKA, which is a company developed by two all-American swimmers from Stanford, has developed glasses and sunglasses that take vision science into account, and have produced an absolutely fantastic product.

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huberman

to get 25% off any of InsideTracker's plans, just use code HUBERMAN at checkout. Today's episode is brought to us by Helix Sleep. Helix Sleep makes mattresses and pillows that fit your unique sleep needs and, in doing so, provide the best sleep possible. I started sleeping on a Helix mattress about a year ago and it is the best sleep I have ever had. If you go to the Helix site, you take a short two-minute test and that test asks you questions like: Do you tend to sleep on your stomach, side, or back?

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huberman

and you will get up to $200 off your mattress and two free pillows. I would like to point you to a valuable resource that is also zero cost and now available online. This is an event that was recorded. The event was organized by Logitech and I was lucky enough to participate in it. And the entire event focused on how to be a more effective student and teacher using modern principles of neuroplasticity. So in the link in the title of this episode, you can go to what was called the Rethink Education Event.

And there I gave a seminar of about 20 or 30 minutes describing the modern neuroscience of neuroplasticity, the ability of the nervous system to change in response to experience. I mainly focused on human studies and how different structures, different things and tools that one can implement in the classroom and outside the classroom can lead to faster, more generalized and longer lasting learning of motor, musical, mathematical and of language. skills, etc., all based on quality peer-reviewed research. So if you want to check it out, you can head to that link. You'll also see an example of some of those tools in action, in a music classroom by a phenomenal music teacher, Ben Edie, a teacher in Pasadena, who has applied these tools, at least as far as I know, for the first time. ever ever Of course, all the tools that exist are listed in what I call a plasticity super protocol, and all of those tools can be applied to learning and teaching in any format you want.

So check it out. It's in the title of this week's episode and it will stay there, it's on YouTube and I hope you enjoy it. Ok, let's talk about nutrition, fasting, health and performance. And I just want to establish some fundamental terms so we're all on the same page. First of all, instead of talking about fasting or time-restricted eating, I'm going to mainly talk about time-restricted eating, but understand that time-restricted eating is only one side of the coin, which is a two-sided coin that includes fasting. on the one hand, not eating and time-restricted feeding; On the other hand, I may occasionally say fasting, but because fasting and eating establish different biological conditions in the body, time-restricted eating is the term I will use to describe time-restricted eating. general plan of restricting the feeding period as it is referred to as a particular phase of each 24-hour day or, in some cases, two particular days within the week.

Because, as you'll soon learn, there are aspects of time-restricted eating, also known as fasting, that involve eating every other day, or eating one way for five days and then fasting for two days, and so on. So I'll be very precise about what I mean and why I mean it. But for now, I'm going to address time-restricted feeding as a way to put an umbrella over this conversation. Secondly, I am going to emphasize many mechanismsbiological. If you've listened to this podcast before, you know that I always start with the biological mechanism. I describe tools on how to implement those mechanisms, but I truly believe that knowing the mechanisms and understanding how these processes work gives you tremendous flexibility, understanding, and control over your physical and mental health processes.

Whereas if I were to list a menu of do's and don'ts, they'll work, but they won't give you the kind of understanding that would allow you to navigate life, travel, dinners, different exercise schedules, whether you have one or not. age or another, whether you are a man, a woman, etc., I am giving you mechanisms so that you can gain more control over the systems of your brain and your body. Everything has a timestamp, so if you want to move on to to-dos, you certainly can, but I encourage you to wait for the mechanism. I'll make it all very clear because if you understand the mechanism, you are in a true place of power and control over your biology.

If there was ever a topic that is a controversial topic, especially on the Internet, it is that of diet and nutrition. So I'm going into this with a smile and eager anticipation of all the buts but this and but buts that, and wait, but this proved that. Here's the deal: we need to define precisely what we're talking about when we talk about nutrition. I'm going to give you an example of a study that was published a few years ago, in 2018, by a colleague of mine at Stanford, Chris Gardner, he is an excellent professor of nutrition and has done many important studies on how nutrition works. impacts different aspects of health.

This is a large scale study. It was published in JAMA, the Journal of the American Medical Association, one of the premier journals in the area of ​​medicine, and certainly for a nutrition article to appear there meant it had to meet an extremely high standard. This article, of which Chris is the first author, Gardner et al, 2018 JAMA, looked at weight loss in people following a particular diet versus another particular diet. And this was a 12-month weight loss study. Therefore, they focused specifically on weight loss, although they also looked at some other parameters. And the basic conclusion of the study was that there was no significant difference in weight change between people eating a healthy low-fat diet versus a healthy low-carb diet with significantly more fat in the diet.

This caused a lot of repercussions in the world of nutrition and nutritional science, and certainly in the general population, because anyone who understands diet and nutrition would immediately say, but wait, there are all kinds of different implications of eating one type of diet, Let's say low carb and high fat, versus a high carb, low fat diet. And indeed there are. This study specifically focused on fat loss and weight loss. So as we look at time-restricted eating, we need to be very precise about what the effects of time-restricted eating and eating in particular ways at particular times are.

Let's emphasize again whether or not the study was conducted in mice. or in humans, in athletes, in men, in women or both, but the study by Gardner and his colleagues is a beautiful study and really emphasizes that if the main goal is simply to lose weight, then it really does not matter what one eats as long as that the amount of calories burned is greater than the amount of calories ingested. However, anyone who understands a little or a lot of biology will agree that there are many factors that influence whether calories burned are part of the equation.

Some of them are obvious. So, for example, amount of exercise, type of exercise, basal metabolic rate, how much energy one burns just sitting there. I've talked before on this podcast about NEIT, non-exercise-induced thermogenesis, where if people jump a lot and move a lot, they can burn between 800 and 2,000 calories a day. So their quote-unquote basal metabolic rate is actually much higher simply because they're restless, whereas people who tend to be more stationary have a lower basal metabolic rate, on average. There is great science to back this up. Metabolic factors and hormones are also very important. Hormones, such as thyroid hormone, insulin and growth hormone, and sexual history of hormones, testosterone and estrogen, those levels will also profoundly influence calories burned, the calories burned component of the calorie equation that come and go.

So if on the Internet or listening to a podcast or a particular speaker, someone says, this is the ideal diet, or calories in, calories out don't matter, or calories in and calories out are the only thing. does matters. I think it's very important to understand that there are some fundamental truths, such as calories consumed and calories expended, but of course hormonal factors and the context in which a certain dietary regimen is carried out are extremely important. important. A good example of this would be puberty, at that time in life, sex steroid hormones are changing profoundly in the body like our growth hormone and other hormones.

And much of the caloric intake is directed towards protein synthesis, the production of muscles, bones and other tissues in the body. And that is due to the hormonal changes we call puberty. So there is no way that we can delve into every aspect of a given meal plan or eating program that allows us to take advantage of every aspect of the list that I read before losing weight, losing fat, muscle organ, genome, epigenome, inflammation, exercise, cognition, mood and life expectancy. But today, we're going to be very precise about how time-restricted feeding, it's very clear, in both animal and human studies, that it can have a very powerful and positive impact on everything from weight and fat loss up to various health parameters.

This is beautiful literature that has emerged mainly in the last 10 or 15 years. And as we go through this literature, what you will see is that there is actually a perfect diet for you on any given day. And that perfect diet for you on a given day is contextual, that is, it depends on what you did yesterday and what you are going to do tomorrow. So there is a perfect diet for you. And today, I'm going to give you the mechanisms and understanding that will allow you to define what that perfect diet is and allow you to eat on a schedule and eat the things that best serve your goals.

So let's talk about eating and what happens when you eat, and let's talk about fasting, or not eating, and what happens when you fast. I did a whole episode on diet, metabolism, hormones, and other factors that affect appetite. We don't have time to go into all those details now, although you can also listen to that episode, but we can briefly describe the general conditions that are established in the body when we eat and when we don't. eat. The key word here is conditions. If I can emphasize anything today, it is that what you eat and when you eat it set conditions in your body, and those conditions can be very good or very bad for you, depending on when you eat.

In fact, when you eat is as important as what you eat. I repeat, when you eat is as important as what you eat, at least when it comes to health parameters, in particular liver health and mental health. Some simple rules about eating. First of all, when you eat, normally your blood glucose level, your blood sugar level, goes up. Additionally, insulin levels will increase. Insulin is a hormone that participates in the mobilization of glucose from the bloodstream. How much your glucose and insulin rise depends on what you eat and how much you eat. In general, simple sugars, including fructose from fruit, but also sucrose and glucose, and simple sugars will increase insulin and blood glucose more than complex carbohydrates.

Things like cereals, breads, pastas, etc., and cereals, breads, pastas, etc., will raise blood glucose more than fibrous carbohydrates, like lettuce, broccoli, and things like that. Protein has a somewhat moderate or modest impact on insulin and glucose, and fat has the least impact on increasing blood glucose and insulin. So what you eat will affect the sharp rise in blood glucose and insulin. And there are a number of factors related to your individual health that will also determine how steep and high that glucose and insulin spike will be. For the moment, I leave out people who have type one diabetes.

These are people who don't make their own insulin, and type two diabetes is essentially insulin insensitivity, lack of insulin sensitivity, which leads to high blood glucose levels. But, when you eat, your blood glucose goes up, and when you don't eat, your blood glucose and insulin go down. The longer it has been since your last meal, the lower your blood glucose and insulin levels will generally be. And the higher, things like GLP1, glucagon-like peptide 1, glucagon being a hormone that's also secreted when you're fasting or in a low blood glucose state. It is involved in mobilizing various energy sources in the body, including fat through what we call lipolysis, it also uses carbohydrates and potentially even uses muscle as an energy source.

So, that's kind of a hosepipe of information about what happens when you eat and don't eat, but think about it this way, blood sugar and insulin go up when you eat, go down when you don't eat, and other hormones go up when you don't eat. . So there are hormones associated with the state of fasting and there are hormones associated with the state of eating and having recently eaten. Now, the most important thing to understand is that, like everything in biology, this is a process that takes time. So insulin and glucose go up when we eat, and it takes a while for them to go down, even if we stop eating, they'll stay high for a while and then they go down again, it takes time.

This is very important, because if you look at the scientific literature on fasting and time-restricted eating, it is absolutely clear that the health benefits, not just the weight loss benefits, but the health benefits of time-restricted feeding, occur because certain conditions are met in the brain and body for a certain period of time. And that gives us an anchor from which to view what eating is in terms of how it sets conditions in the body over time. And if this sounds too analytical, I promise you that this is the best and simplest way to think about any schedule or eating plan.

So I think it's fair to say that in the field of nutrition, there are some landmark studies that serve as really strong anchors for developing our understanding of what to eat, what not to eat, and when to eat, depending on our goals. The Gardner study I mentioned above is one of those studies, as it says that if your goal is to lose weight, it doesn't really matter what foods you eat, as long as you eat a low-maintenance calorie diet. However, I want to emphasize again that this leaves out questions of adherence, that is, how easy or difficult it is to follow a given diet.

Some people find it much easier to follow a high-fat, low-carb diet. Some people fall and follow a different diet because they find it much easier to follow. And some people are concerned about mental performance and athletic performance. So that study doesn't say there is a best diet, what it says is that what you consume is less important than how much food you eat, at least for the sake of weight loss, not necessarily for the sake of health. Now, the study I am going to refer to below is what I would consider the second important pillar of nutritional studies.

This is a truly historic study that was conducted by Satchin Panda, a professor at the Salk Institute for Biological Studies in San Diego, an absolutely phenomenal institution and an absolutely phenomenal researcher. I have known Satchin for several years and want to emphasize that the current literature on intermittent fasting and time-restricted eating can largely be attributed to Satchin and the work he has done. Of course, there are others involved too. And of course, time-restricted eating and fasting has a rich history dating back many hundreds, if not thousands of years, across different cultures and religions, but the science of time-restricted eating can really be Mainly attribute it to the incredible work that Satchin has done.

And I'm grateful to consider him a friend and colleague, and we consulted extensively in anticipation of this episode. I also hope to have you as a guest in the future. The landmark paper that came out of Satchin's lab was published in 2012. It was a mouse paper that laid the groundwork for later human studies. And the title of this article is Time-restricted feeding without reducing intakecaloric, prevents metabolic diseases in mice fed a high-fat diet. So the title tells us a lot. He says what was varied in this study is not what these mice ate, but when they ate it.

And there were essentially four conditions in this study and the results are absolutely remarkable. So I'm going to explain the main results to you. What they did was give the mice access to different types of food. There were four groups, one group of mice had access only to a normal mouse diet. It wouldn't be a diet that would interest him much. I confess that I have tried mouse food. If you work with mice, just do it. At least once it doesn't taste very good, it tastes like a very bland graham cracker. And I confessed it. She only had a little bit, but mice like that stuff.

And if you allow them to eat those things, which is called ad libitum, whenever they want, you just keep them in their food. 24 hours a day, sometimes they ate and sometimes they didn't, or in this case, they also had a condition where they were given mouse food in a restricted time, only for a certain number of hours. hours each day, but about eight hours, or they were given a high-fat diet. That was a separate group, they received a high-fat diet whenever they wanted. So this was a kind of carnival for the mice because mice really like high-fat, very tasty foods.

And so they got a lot of treats and high-fat foods. And then there was a fourth group that had access to the high-fat diet as much as they wanted to eat, but only during a restricted time period of each 24-hour cycle; Now the mice are nocturnal. Humans are what we call diurnal, in reality we are not really diurnal, we are crepuscular, which means that we are more active in the morning and at night, not so much in the afternoon, but still, everything I am I'm going to say it's true for humans too. And now we know this from human studies, one of the most important things that we can take away from this study was that mice that ate a very tasty high fat diet, a great tasting diet, but only during a restricted feeding period of every 24 hours. cycle maintained or lost weight over time, while mice that ate the same diet, amount of calories, but had access to those calories 24 hours a day, gained weight, became obese, and became quite ill.

And as a second bonus point, mice that restricted their feeding window to a particular eight-hour portion of each 24-hour cycle actually showed some improvement in important health markers. And what was even more incredible is that the mice that only ate during a particular feeding period also experienced some reversal of some previous negative health effects. So this study really lit up the world and got people excited about time-restricted eating again. They use an eight hour feeding period. However, the history around that eight-hour feeding window is quite interesting. Not many people know this because it wasn't included in the article, and there was no reason to include it in the article, so as not to give anyone away, but it turns out that the reason they used an eight hour feeding period and not nine hour or a 10-hour feeding window, it is because studies of this type are quite demanding to conduct and require the constant presence of the graduate student or postdoc there to ensure that the food is in the cages at certain times and not in the cages at other times.

And mice are very good at hiding food. They will even hide food in their dewlap. So, there's a lot of work to do to prepare for that eight-hour feeding period. And to make sure that after that eight-hour feeding window, all the food has been removed from the cage and from the dewlaps of the mice, etc. And it turns out that the partner of the graduate student or postdoc, I won't reveal who was applying. This study prohibited his partner, the scientist, from being in the laboratory for periods of time much longer than the 10 or 12 hours that were required to guarantee this eight-hour feeding window.

So when we hear that eight-hour eating windows are sacred, they are not sacred and later we will talk about how to eat during a time restricted to eight hours versus 10 hours versus 12 hours. For example, how that affects various parameters, such as health parameters and weight loss, etc. But the eight-hour feeding window was actually created because of a real-world limitation on the research and the relationship with the researcher doing the research, not because there is anything sacred about an eight-hour feeding window, it's now a important point about when the feeding window falls. Within the 24 hour cycle, it is very important that the feeding window falls during the most active phase of the day, so for humans, that is usually in the first or last part of the day, but not at night.

Simply put, there is currently a lot of data that suggests that eating during the night phase of the 24-hour cycle is very harmful to your health. In fact, when we eat it can improve our health or decrease it. When we see light, we can improve our sense of well-being or decrease it. I've talked about this many times before, on the Human Lab Podcast, that during the day, your eyes need to get as much sunlight and other types of bright light as they can safely get. And then you'll want to avoid the light in the middle of the night.

It has detrimental effects on reducing dopamine, can cause depression, increased cortisol, etc. So when you see the light is as important as the light you see. And when eating is just as important as what you eat, they saw something really interesting in this study, which was that restricting food to a particular phase of the 24-hour cycle not only benefited, but it also benefited things like lean body mass and fat loss, and a number of health parameters that we'll talk about in a moment, but it also anchored all of the body's genetic systems and provided a more regular stable circadian rhythm or 24-hour rhythm, you might be surprised to know that 80%, the 80% of the genes in your body and brain are on a 24-hour schedule.

That is, they change their levels from high to low and back to high again, throughout the 24-hour cycle. And when those genes are high at the appropriate times and low at the appropriate times, it means that their expression is high and low at the appropriate times. And therefore the right RNAs and proteins are produced because DNA encodes RNA, RNA is translated into proteins. When that happens, your health benefits, when those genes are not expressed at the right times when they are higher or lower at the wrong times of each 24-hour cycle, that is when you get negative health effects.

This study showed that when mice restrict their feeding to an eight-hour period within the most active phase of their 24-hour cycle, many of the genes associated with the so-called circadian clocks, these genes have names like PER, BMAL, CRY1 . , etc., those so-called clock genes suffered a very regular entrainment, a blockage in the proper 24-hour schedule. And while this occurred in mice, we now know that this also occurs in humans. I've said it before on this podcast, and I'll say it again, that light, and when we see light, is the primary way that these genes and our body's clock systems organize or adapt, meaning they adapt to the environment. external light and darkness cycle.

So seeing light early in the day and in the afternoon, and as much as possible throughout the day, is great, ideally that sunlight, avoiding light in the middle of the night, is also great. It's great because it causes increases in particular genes and decreases in particular genes in every cell in your body at the appropriate times. The second most powerful timekeeper or zeitgeber, as it's called, is food, and when you eat, and in this In the study, the results that they saw underline this point, what they saw is that the spikes in these clock genes became very regular.

And the drops in these clock genes became very regular. And that led to a lot of really important positive health effects. On the contrary, when the mice ate, whenever they wanted during the 24-hour cycle, these clock genes became really out of control and negative health consequences were the subsequent result of these changes in these clock genes. This has now been shown to be true for humans as well. So if you want to be healthy, you want your organ health and your metabolic health to be properly trained. One of the most important things you can do is, if you lied at the appropriate times of each 24-hour day, not to see the light at other times of that time and eat at the appropriate time of each 24-hour day.

Now, again, there are rare cases that we will discuss where skipping entire days or entire 24-hour feeding cycles can be beneficial. But for now we're talking about restricted feeding schedules which involve a feeding window that falls during your most active phase, so during the day, leaving aside people who work shifts during the day, is when you want to eat. And this eight-hour feeding window provided a very strong reinforcing signal that combines with light to ensure that these genes are expressed at the right time. The short takeaway from this is that you probably want to think about and maybe even engage in time-restricted eating.

So, as I mentioned above, when mice can eat 24 hours a day, bad things happen. And one of the bad things that happens is that the liver suffers, the liver is involved in all kinds of things, production of important hormones and other factors related to metabolism. And when the mice were able to eat 24 hours a day, their livers became seriously ill and fatty deposits built up in the liver. Other factors in the liver essentially influenced the path of liver disease, time-restricted feeding essentially reversed that or led in many cases to even healthier liver conditions, and that's based on this study, but also additional studies now in humans.

Therefore, it has now been clearly shown in mice and in humans that restricting feeding to a particular period, each 24-hour cycle, improves liver health, which is wonderful. How do you do this? Well, it happens because the intake of food, as I mentioned above, sets certain conditions in the body that last for a period of time. Every time we eat, whether or not we are a mouse or a human being, there is a period of time that is required for so-called digestion, but also for gastric emptying and other processes related to the breakdown of that food and its utilization.

And that is an active process. Requires energy. And that process of breaking down food involves certain cellular functions that, if they continue throughout the entire 24-hour cycle or even extend too far throughout the 24-hour cycle, it means that you're eating over a 14- or 16-hour period, or 18 hours. , that causes serious problems. And this has now been established due to the fact that it increases the expression of different proteins and genes in the body, such as TNF alpha, IL-6, IL-1. What are all those things? They are proinflammatory markers. So the reason the liver gets sick when you eat too frequently is because inflammatory markers increase.

These inflammatory markers are not inherently bad, they are there for a reason, but they are there to respond to certain challenges, immunological challenges or the ingestion of food and its breakdown. But then, in an ideal circumstance, they are reduced in the period when there is no food present in the digestive tract or when there is very little food present in the digestive tract. So by eating 24 hours a day, you make yourself sicker by eating in restricted periods of time, every 24 hours a day, you are actually becoming healthier and you are activating certain processes that can positively impact both weight and health. maintenance. or weight loss.

We'll talk about weight gain a little later and how to positively impact things like liver health. Also the expression of different things related to brown fat, the fat that increases your metabolism. We'll come back to this a little bit later as well and blood glucose regulation, so there are actually a lot of takeaways from the study. It's wonderful that liver health, bile acid metabolism, energy expenditure inflammation, liver metabolites and many, many aspects of our health are affected by when we eat, not just what we eat , as we go on, and talk about intermittent fasting. for eight hour periods, six hour periods, 12 hour periods for all kinds of different intentions and purposes.

I want to start establishing a fundamental protocol that all of us, any of us, can use to maximize our particular goals. There are some absolutes within this realm of time-restricted eating. Here are a couple of absolutes you might want to consider: inFirst of all, it's worth it in a metabolic sense and in a health sense and in a weight maintenance or weight loss sense to not eat any food in the first hour after you wake up and potentially for longer, so I want to say it again. One of the key pillars of intermittent fasting is that for the first hour after waking up and potentially longer to not eat any food is okay, the second important pillar that is well supported by research is that for the two and ideally three hours Before bedtime, do not eat any food or liquid calories either.

And we'll talk about what it means to break a fast and whether certain liquids, even coffee and tea can break a fast, et cetera, in a few moments, but just as a basis, it's very clear from human research. You should not eat any food or consume liquid or non-liquid calories during the first 60 minutes after waking up each day. And for the two to three hours before bedtime, that's ideal for the parameters that we've discussed before, all the different things like weight and liver health and metabolic health and so on. The two most common questions about intermittent fasting are when is the ideal time to eat?

Is it early in the day, middle of the day, or later? And how long should that eating window last? Should it be eight hours? We have already heard why the eight-hour deadline was first established. It was because of these lab conditions and the conditions of the particular relationship of the graduate student involved, or should it be seven hours, six hours, or 12 hours. It turns out that there are some general frameworks we can follow to answer these questions. As we move into this part of the discussion, I want to highlight a very important reference that just came out, it literally came out last week in the endocrinology journal reviews.

And the title of this review is Time Restricted Feeding for the Prevention and Treatment of Metabolic Diseases. Although the data in this article goes far beyond metabolic diseases, it is an article from Satchin Panda's laboratory. It is a very extensive review with a huge, beautifully organized table outlining all the studies done on humans. Over a hundred studies looking at time, restricted eating in athletes, men, women, children, diabetes, non-diabetes, etc., with detailed references and description of results. I've spent a lot of time on this review, even though it was just published recently and it's a real gold mine.

It's also the primary resource for everything I'm going to tell you if you want to delve deeper into the material. So let's address this first question of when is the ideal eating period, and here again, we're thinking about an eating schedule that involves eating at least once every 24 hours, not two days or three days or every other day on an empty stomach. So it turns out that the answer to the question of when is it best to eat is best answered by thinking about the other side of the coin: when is it best to fast? So, since we fast during sleep, it is very clear that it is best to extend sleep-related fasting into the morning or start it in the evening.

Now, this may seem obvious, but it's actually not so obvious. You can place that feeding window early in the day, in the middle of the day, or at the end of the day. Let's think about what happens when we sleep, when we sleep our body goes through a series of different processes in the brain and body to recover cells and tissues. Many of you have probably heard of autophagy, which is essentially a cleansing, swallowing of dead cells and injured or diseased cells. And this is a natural process that occurs, and it occurs primarily during sleep. Although not only during sleep, fasting of any type tends to improve autophagy.

It is not the only way to create autophagic conditions. Autophagic conditions can be created simply by following a subcaloric diet. And there are other things you can do to trigger autophagy, but fasting does trigger autophagy. So when we sleep, the bad cells are devoured and devoured. And the good cells are also undergoing certain repair mechanisms primarily related to, or at least governed by, those circadian genes that we talked about earlier, the clock genes. So, you are already fasting when you are asleep and how deep you are in that fast depends on how much time has passed since your last meal.

So if you fast early in the day and you've been asleep for 5, 6, 7, 8 hours, I would expect six to eight hours for most people to be beneficial. When you wake up, I mentioned earlier that you don't want to eat for at least the first 60 minutes after you wake up, but if you were to extend that fast to say, 9:00 a.m. m., 10:00 a.m. m., 11:00 a.m. m. o Even at 12 noon or later you are taking advantage of the deep fast you did during sleep. And certainly towards the end of the dream, now, why do I say deep, fast?

Well, because when we eat, the elimination of that food from our intestine and the processes in our cells and organs that are related to digestion, and the utilization of that food takes between five and six hours, so if you eat one meal and that food lasts 10 minutes, 20 minutes or 30 minutes, or even an hour, and then you stop eating, you have stopped eating, but you are not fasting at that time. You can say you are fasting because you are no longer putting food into your digestive tract, but you are not in a fasting state. You are not under fasting conditions, later I will talk about things you can do to accelerate the transition to fasting.

So one thing is for sure: you want your eating window to be added to or linked to your sleep-based fasting in a way that makes it easier for you to enter the fasted state for a period of time. So we can look at that point from the perspective of the best, the best and the worst, okay? So if you're like most people and you sleep at night, you'll wake up around 6:30, 7:00 a.m. m. or maybe even at 8:00 a.m. m. Let's say you were to extend your fasting window, so that you started eating at noon and then stopped eating at 6:00 p.m.

Well, then you haven't been eating since 6:00 p.m. m. until let's say your bedtime is 10:00 p.m. m., but from 6:00 p.m. m. until 10:00 p.m. m., your body is not yet in a fasting state because you just ate. However, you are starting to gradually taper off to a faster state before sleep and then throughout sleep. And until the next morning and late morning, you are actually in a state of fasting; Now, most people find it very difficult to eat alone in the middle of the day, so while that is best, it is ideal for improving fasting-related health. health, it is not ideal.

And it is not very applicable to most work, family and social situations. Most people have breakfast with other people or dinner with other people. Some people eat lunch with others, but in general, it's difficult to restrict the eating window to the middle of the day, but from a purely health perspective, in a very objective way, that would be the ideal situation. Let's imagine a different feeding pattern in which the feeding window begins around two or even three in the afternoon. Some people don't have much trouble or can train themselves to have their feeding period between two or 3 p.m. m., and then they won't eat until 10 or 11:00 p.m. m.

Well, if you do the math, you'll realize that that feeding window is still pretty short. It still constitutes what we would call intermittent fasting or time-restricted eating. But assuming they go to bed around 11:00 p.m. or midnight, they're not actually fasting while they're sleeping because for the first six hours of sleep, maybe five, but probably more like six hours of sleep, they're still digesting. the food they ate late at night. It seems beneficial to take that sleep-related fast, meaning you don't want your eating window to be too close to bedtime. And that's why we came up with this kind of fundamental pillar that I talked about before, which is at least not eating for the first hour after you wake up, but also not eating two or three hours before going to bed.

And because we all need sleep and sleep is apparently important for our health of all kinds. You want to prioritize sleep, but since we also have to eat, then you start thinking about this and maybe it's not so good to delay that eating window too late in the day, because when you go to sleep, you're not actually taking advantage of the fast. related to sleep. Now, it's not just that it's easier to fast while we sleep, although that's true because when we sleep, we're typically not hungry or looking for food, looking for food, wanting food, or trying to resist food.

We're just sleeping. There is something special about fasting that occurs during sleep, because it is associated with a series of processes that relate to the so-called lymphatic system, the movement of lymph-like fluids and other fluids through the brain, and a kind of sweeping The trash. elimination, so to speak, a cleanup of metabolic waste and some of the autophagy associated with bad processes in the brain. So we could do a whole episode on this, but essentially during sleep, and in particular, during fasted sleep states, we are going through a series of automatic processes that clear waste from our brain and improve cognition, or at less compensate for dementia.

This is already well established, as are many of the same processes that occur in the organs of our body. So what we're starting to see here is that there are a number of limitations on when you can eat. Now, I would be remiss if I didn't recognize the social constraints and the constraints of real life, some of us, because we want to eat with our family and because our family or our partners eat around eight or nine at night, and that's The only time we are together, we have to eat late in the day. And that is certainly not a sin.

I'm not saying it's good or bad, here we try to establish, if you remember, the best, the best and the worst. So, from both a practical and health perspective and a purely objective view of how intermittent fasting works and how it can benefit us, start eating every day, around 10:00 a.m. m. or around noon, and then allow a feeding period lasting until six o'clock. or maybe at 8:00 p.m. It seems to me, at least based on the data and what I understand about typical cultures, where people eat during the day and at night, that seems like the kind of schedule that will allow you to make the most of the intermittent schedule. fasting and time-restricted eating, but it doesn't predispose you to being really out of sync with the social rhythms in most cultures.

If you think about it from the perspective of, say, an eating period from noon to eight, what you'll find is that you can eat lunch with other people. If you wish, or only, you will be able to dine at a reasonable time, at least in most countries, in most cultures, dine between 6:30 and 7:00 p.m. It's typical. When you say a feeding window, that goes until eight. That doesn't mean sitting down to dinner at eight. That means your last bite of food or liquid calorie intake was at 8:00 p.m. Assuming you go to bed between 10:00 p.m. m. and 1:00 a.m. m., that will allow you to gradually taper off, or transition from eating to a fasting state, and still allow you to take advantage of the special fasting period related to sleep. fast.

And again, I want to emphasize that fasting that occurs during sleep is vital and eating too close to sleep will disrupt fasting-related sleep. Now, there are a number of caveats and details related to this, and there is one important caveat in detail related to people who are specifically interested in increasing or maintaining muscle mass. So, first let's talk about the volume and type of food and how they relate to whether you quickly or slowly enter a fasting state. Because clearly, when we talk about an eating window, that eating window could include any number of different foods, it could include cakes and ice cream, pizza, burgers, plants, fruits, whatever, or it could involve just fat or just protein. , etc.

There are at least three factors that will govern how quickly you go from eating food to a fasted state. Remember, when you take your last bite or sip of calories, that is not when the fast begins. That might be when you start fasting on your watch or on one of these apps I'll get to later, which can help you track your fasting and eating periods. But that's not when it really starts because your body still sees food. In reality, you carry food inside you, although you do not put it in your mouth, in a sense you are still eating.

Therefore, it should be somewhat obvious that very large meals will take longer to digest than very small meals. That will affect how slowly or quickly it migrates from a fed state to afasting state. There's no way I can explain to you exactly what volume of food you should eat based on the size of your stomach, etc., but you're all familiar with being extremely full, very full, comfortably full, somewhat full, or not feeling full. and feel hungry. That is why it is important to learn to measure the volume of food. Also foods that include some fats or a lot of fats will tend to slow down gastric emptying time.

And depending on the type of fats, it could mean that a given meal is digested in three hours versus five hours. And more fats can be that a large meal with a lot of fats can take five or six hours. A smaller meal with less fat will be digested more quickly. Consuming calories in liquid form will mean that gastric emptying time will be faster. And then, of course, there's the glucose and insulin aspect, which are the foods that cause big spikes in glucose, like pure sugars. Then your glucose will go down, however, if you combine them with fats, then it tends to be a more gradual increase in glucose and it's more sustained, etcetera.

Fibrous foods will also create a longer-lasting sustained release of glucose. The important thing here is to set a feeding window that you can comfortably manage, okay? Which means that, on average, it can follow a six-hour feeding period, an eight-hour feeding period, or a 10-hour feeding period. And then to put that feeding window into a social and living context that can be managed on a regular basis, there are now two key points that have been drawn from the scientific data about this feeding window and when to place it. And this is based on a really important experiment that Satchin and his colleagues have been doing.

There is a website that has a zero cost website called My Circadian Clock, you can visit this website free of cost. There are a number of important resources there, but what they've done is examine the eating behavior of thousands of people. People will take a photo of the food they are about to eat and enter it into their account, maybe your account, if they create one in My Circadian Clock and do it over many days or weeks, the nice thing about this is that it establishes what is essentially called fetal gram, the time at which people ate.

And from these fetal grams a number of important findings have emerged, in large populations of people, different time zones with different schedules, etc. First of all, almost everyone underestimates their feeding window. That is, people who think they are in an eight-hour or six-hour feeding period, when their data is analyzed, it is almost always the case that they are actually in a feeding period that is one or even two hours longer than they think. You think, well, how could that be if people take their first bite at noon and their last at 8:00 p.m.? Well, that must mean they're in that eight-hour feeding window.

And it turns out that people cheat, but they don't do it in any obvious way. They could have, you know, a glass of wine after dinner, or have a cup of tea and a bite of a cookie. So when people are honest, and they are, in most cases for this experiment, what you find is that most people's eating window is actually a little bit longer. So, in discussing this with such people and reviewing the literature, it is clear that if you want to be on a 10-hour feeding period, you should probably select an eight-hour feeding period, because there is always a small reduction in on either side of that window to eat.

Very few people are extremely strict about these eating windows. It's just hard to do in the context of life events and social gatherings, family, etc. Well, as we move forward, your ideal eating schedule with restricted fasting time, we now have several different rules that we can list first, at least no food for the first hour after waking up, at least one hour, two, no. Food intake for two and ideally three hours before bedtime. Three, if you want to select an eight hour feeding period then you should probably focus on a six or seven hour feeding period because in reality your feeding period will be a longer reality i.e. real life limitations .

And if you want to be on a 10-hour eating window, you should probably select an eight- or nine-hour eating window, because the way it plays out is that people almost always eat outside of their eating window, sort of. . The other advantage of selecting a slightly shorter eating window that is more comfortable for you is that it takes into account that as you take that last bite or sip of calories, there is a time or gradual reduction before, in which You are actually fasting. And because you eat different things on different days, presumably some foods leave your gut more quickly.

Some things raise your insulin and glucose more than others. Sometimes you eat more fat, sometimes less fat. This allows you to stay within the range of the benefits of time-restricted feeding that have been shown in humans, which typically involve a period of approximately eight hours. So I think this eight-hour or six-hour window is a good thing for most people, for some people, and we'll discuss the exceptions, but some people really are exceptions to this. They just need more food. And on that note, I now want to briefly touch on some of the studies that have looked at using a very short feeding period of about four hours;

Nowadays, several people are making the so-called one meal a day, or are restricting their eating window to just four or six hours. And that turns out to be an interesting strategy and the data surrounding it is a bit surprising. One surprising thing that emerges from this massive review of the literature on time-restricted feeding in humans is that relatively short periods of feeding, say four to six hours, produce a number of positive health effects. Things like increased insulin sensitivity, which we know is good, remember type two diabetes is a reduction in insulin sensitivity, improvements in beta cell and pancreas function, decreased blood pressure, decreased of oxidative stress, decrease in things like nighttime appetite.

Such positive effects for health and psychological facts in general. However, they either produce no changes in body weight, or they tend to produce uniform increases in body weight; Now, of course, there is variation between individuals and between studies, but this is somewhat surprising. So the eight-hour feeding window seems to be very beneficial in almost all the parameters that we've discussed: inflammation, weight, loss, fat loss, etc., and adherence. I should mention that people's ability to follow the diet seems pretty good in these eight hour eating periods, but when people try to undergo very short four to six hour eating periods, it seems like they are overeating in those four to six hours, at least eat less in excess relative to your metabolic needs.

Now, the contrast to this is the so-called one meal a day program, very few studies on one meal a day, one meal a day, unless it's a very, very long meal, some kind of feast that normally wouldn't last four to six hours because it depends on how you define a meal. But when you look at the very few, I must emphasize, again, very few studies on one meal a day. People typically maintain or lose weight on a one-meal-a-day schedule. So what we can say is that the seven to nine hour feeding period produces all of the major health benefits of time-restricted feeding, plus it's pretty easy for most people to follow on a regular basis. . be very important.

I will return to that point in a moment. While the four to six hour eating window doesn't seem to be as helpful to people as, say, a seven or eight hour eating window, simply because people overeat during that eating window and the only meal per day, although it may be ideal for certain people's schedules. It can actually cause people to undereat. And in some cases that might be what people want. In fact, they want to eat less. But when we start to think about work and sport, and when we start to consider hormonal health and hormone production, that's when we can really start to look at the seven to nine hour feeding period versus the four-hour feeding period. to six hours versus the one meal per day type of eating window with a different objectivity, we can start to look at it through a different lens because it turns out that when you put the feeding window and the length of that feeding window actually will affect a number of other things.

In particular hormones, which can be very important for a number of things related to sex and reproduction, can be related to performance at work and performance in athletics. And there are excellent studies about it. So let's explore those now. So let's talk about some conditions where having the feeding window early in the day would actually be very beneficial. There was a study that was recently published in Cell Reports, again, Cell Press Journal, a great, very strict, peer-reviewed journal by Aoyama et al, so this is AOYAMA et al. This was recently published in July 2021 and looked at the distribution of protein intake across different meals delivered early or later in the day.

And I'm summarizing a lot here, but I should mention that this study was done in both mice and humans, same paper, mice and humans, and it involved hypertrophy training, essentially increasing the weight bearing of certain limbs to try to induce hypertrophy, which is the growth of muscle tissue. It appears that muscle tissue is more capable of hypertrophy by virtue of the fact that there is better or greater protein synthesis early in the day, due to the expression of one of these particular clock genes called BMAL, BMAL, BMAL regulates a number of different protein synthesis pathways within muscle cells, so eating protein early in the day supports the maintenance or growth of muscle tissue.

And in this study, they also looked at the effects of supplementing the so-called branched chain amino acids BCA, which are popular in bodybuilding circles and in strength training circles and BCAs are essential components of several different foods, but also they can complement each other. . The conclusion of this study is quite simple. However, the bottom line is that if your primary interest is maintaining or building muscle, then it may be beneficial to eat protein early in the day; You will still want to obey this, what we call a kind of fundamental no-eating rule. , do not eat any food for the first hour after waking up or at least for the first hour after waking up.

And the limit for when you would want to eat protein would be before 10:00 a.m. And there I am averaging several different situations, but in general, this BMAL expression is such that let's say you wake up at 7:00 a.m. Its main interest is hypertrophy or muscle maintenance. Then you'll want to get some protein in before 10:00 a.m. But obviously, if you're interested in getting the health effects of intermittent fasting, don't eat any food for at least the first 60 minutes when you wake up. Now it's not that at 10:01 a.m. m. If a door slams shut and you cannot generate hypertrophy, of course that is not the case.

However, it is very interesting that no matter when resistance training, loading exercise occurs in the 24 hour cycle. So in other words, whether or not people train early, or at the end of the day. It still appears that ingesting protein early in the day promotes hypertrophy or that one is better, or should I say more easily able to access hypertrophy through these clock-regulated protein synthesis mechanisms, by ingesting protein early in the day No way, does this study say that eating protein later in the day is somehow bad for you? It simply emphasizes the positive effects of eating protein early in the day for muscle maintenance or hypertrophy.

So if you're someone who primarily cares about muscle maintenance and hypertrophy, then it may make sense to move that eating window earlier in the day. And there are certainly people who are interested in muscle maintenance and hypertrophy, who don't do any intermittent fasting, and that's perfectly fine too, but it turns out this is an episode about intermittent fasting and time-restricted eating. Of course, there are ways of eating in which you eat small meals spread throughout the day or weigh yourmeals differently. So that meals early in the day are larger than those at the end of the day or vice versa.

There are an almost infinite number of ways to organize this. But if you are someone who is interested in obtaining the many clearly established health effects of time-restricted eating, and you are someone who would like to maintain or build muscle, then it would be important to eat protein in the first part of the day. at least based on these results. And so, that eight-hour window that we've established as more or less ideal moved to the latter part of the day might not be as beneficial for you. Now I can say it personally for me. When I wake up in the morning, I find it very easy not to eat until noon, one or two in the afternoon.

Eating early in the day is actually quite a challenge. I brought up this point with Satchin, because we were talking about how you can change your eating window or put yourself on a different intermittent fasting schedule. And it is very clear that a transition period needs to be provided for that to happen; You should allow yourself a transition period of between a week and 10 days where you change your feeding window by about an hour each day or so. And then, once you establish a feeding window that you are comfortable with and that you think you can maintain over time, simply maintain that feeding schedule for at least 30 days, but ideally indefinitely.

Now, this turns out to be important based on the data they've gotten from this massive My Circadian Clock experiment they've been doing, where people enter the times that they feed and eat. Excuse me, whenever we talk about mice, I always think about diet because I come from my laboratory and work on both laboratory mice and humans. And every time I think about humans, I think about eating, but of course they are the same thing. The interesting thing that comes out of that large data set in humans is that when people record their eating times, as I mentioned before, many times they think they are eating in an eight-hour period, but in reality they are eating in a much longer period. broad. .

However, even for people who are very good at restricting their eating to a four-, six-, or eight-hour window, if they are very strict about start and stop times and when they eat calories, one of the findings that has been really important. It should be noted that almost all individuals have a large variation when that eating window is in their 24-hour period. Particularly on the weekends, people extend or change their eating window in a way that makes it seem like they have traveled to another time zone and are eating according to another time zone. And this is extremely important.

As I mentioned earlier, according to a 2012 study from Satchin's lab, eating at a particular phase of each 24-hour cycle can help improve the expression of these clock genes. If you are eating within a very strict or semi-strict eating window, but that eating window migrates from one day to the next or five days a week. You're really organized as to when it falls, say, for example, from noon to 8:00 p.m. m., noon to 8:00 p.m. Monday at noon, Tuesday, Wednesday at noon to 8:00 p.m. m., Thursday, etc. forward. But then, on Saturday, it's 11:00 a.m. m. and you finish it early, or maybe you start early in the day on Sunday, have a brunch that starts at nine-thirty or ten, and then goes on even longer. only eight hours.

But changing that can cause disruptions in circadian clock mechanisms that lead to disruptions in the aftereffects of feeding, from which it takes at least two to three days to recover. Obviously we don't want to be too neurotic about this topic, but since this is an episode about the science of intermittent fasting and time-restricted eating, just as important as the length of the eating window is where that eating window resides in each 24 hour cycle. And perhaps even more important than that is to be fairly regular about where that feeding window resides. Because even if you have a very short eating window, if it varies from day to day, that actually counteracts a number of positive health effects of intermittent fasting.

So, to really underscore how these different pieces of the biological puzzle fit together, if you are very strict or semi-strict about your eight-hour eating window, but on the weekends that eight-hour eating window drops further later than normal during midweek. It's like you go to bed later, even if you go to bed at the same time, at least from a metabolic health perspective, because of the way eating impacts these clock genes and impacts, or should say subtraction, the sleep-related fasting that you would normally experience if you finished eating that a couple of hours before bed, so again, we don't want to create any overly obsessive or neurotic focus on this, I think most, all people might benefit from a restricted feeding schedule, but they should really think carefully about what they can do on a regular basis and understand that they tend to underestimate the feeding window, that they are actually participating, and that they need to put that feeding window in one part of the cycle of 24 hours in which they can be consistent most days, and I want to emphasize most again, because we are not lab mice.

We don't have a grad student come in eight hours a day because that's what their partner will let them do. And then by removing the food from our dewlaps and from our cages, we have access to food practically 24 hours a day, in that sense, however, there are things that we can all do that will allow us to compensate for some of the drift. so to speak, that we experience or that we induce in terms of when our feeding window occurs or that the feeding window might push out a little bit later and therefore start a little later, the next day, there are things What we can do there, things we can take.

That is why I would like to discuss them briefly. So throughout this episode, I've been more or less alluding to the fact that when you eat, there's a period of time afterward where you're actually still eating, at least from a metabolism perspective, because glucose rises, Insulin is up and you're going through different metabolic and digestive processes that don't really indicate that you're in a fasting state, right? It's not just about when you take the last bite or the last sip. However, there are things we can do to speed up the transition from a fed state to a fasted state.

And so I would like to discuss what they are. And I want to emphasize that the term fed state is probably a better way to think about it than eating or not eating because we think of eating the verb, we're eating, we're eating, okay, we're done eating. I'm fasting now, but you're not actually fasting because you're fed. So we should really think about the fed and unfed states because from a vendor processes perspective and from a health perspective, that's actually what your body and your system is paying attention to. And now, with everything we've laid out, I think it should be intuitive to understand.

There is a fun and exciting concept related to this: glucose disposal. You may have heard the old saying that walking for 20 or 30 minutes after eating dinner speeds up the rate at which you digest that meal. And indeed it does, removing glucose from your system can be achieved through a number of different means, but light movement or exercise increases gastric emptying time, so, for example, if you were to eat a meal that ended to 8:00 In the afternoon, and then flopping on the couch, watching TV, sitting on the computer, or going to sleep, it would be five or six hours until you have gone from a fed state to a fasted state.

However, you can speed up considerably by taking a light 20 or 30 minute walk, it doesn't have to be a brisk walk. It is certainly not necessary to jog, but simply walk outdoors or move around. Therefore, glucose disposal is an important aspect of the transition from the fed state to the fasted state. And just a light walk can allow you to do that, now if you can't get out, some people will do gymnastics, literally do things like air squats and push-ups and things like that, and they will actually increase. the expression of things like glut four and things that mobilize glucose into the muscles and things like that, but, you know, in most conditions, most people don't do push-ups after dinner, or certainly They haven't had a great meal. , simply taking a brisk walk can be beneficial.

Additionally, you might consider doing intense exercise. Now, you don't necessarily want to do this right after eating. So let's take a look at what high-intensity training of any kind does to blood glucose, because in this case, it turns out that when you do high-intensity training it actually has opposite effects on blood glucose, depending on whether you do it or not. early or later in the day. So a fairly recent study looked at so-called hit training, high-intensity interval training, which of course can take many different forms. It can take the form of circuit training with weights. It can take the form of, you know, burpees, push-ups, sprints and all kinds of different things.

But high intensity interval training is typically training that gets people's heart rate up, you know, well above 70% of max and then short periods of rest and then repeat and of course the duration will vary as well. of high intensity interval training. There are very short workouts, you know, six, 12 or 15 minutes. Some people can continue high-intensity interval training for up to 45 or even 60 minutes in extreme cases. But when we look at the studies that have explored high-intensity interval training and its effect on blood glucose, there are a couple of studies that stand out, for example one that emphasized that blood glucose levels will actually increase if training is practiced in high intensity intervals.

It is done early in the day and will decrease if high intensity interval training is done later in the day. Now, the purpose of this exploration was not to explore the elimination of blood glucose through intermittent fasting. It mainly focused on athletic performance and whether it was better early or later in the day, etc. But we can extract some information from these studies that is beneficial for understanding glucose disposal. If you have eaten during the afternoon, at night and at the end of the day, and are thinking about going to sleep and would like to do so in a way where you are less fed and more fasted, then do high intensity exercise.

Interval training in the afternoon will lower or, should I say, in the evening, reduce blood glucose. And that way it will help you speed up your transition to the faster state as long as you don't eat something after high intensity interval training. Now, the increase in blood glucose that occurs with high-intensity interval training early in the day is not necessarily harmful. This is often associated with the transport of nutrients to the muscles. They just worked very hard. So, it's not that high-intensity interval training shouldn't be done early in the day; In fact, for many people, including me, training early in the day, just because of the way my psychology and biology works, is always better for me than training later. on day.

And the other important thing to mention is that high-intensity interval training done late in the day can be beneficial from the perspective of clearing glucose, lowering blood glucose, and helping to transition from fed to fasted states in preparation for sleep. However, if you're ingesting caffeine or anything else to do that high-intensity interval training in a way that prevents you from getting a good night's sleep, then it's going to be detrimental overall. So the reason I mentioned this is, of course, because it's good to know that light walking after dinner or any other meal, or high-intensity interval training, as long as it's done in the second half of the day , can lower blood glucose and speed up the transition. from fed states to fasted states.

But I also mentioned it because what we're really trying to achieve when we engage in intermittent fasting, so-called time-restricted eating, is accessing unfed states or fasting states. It's not really about when you eat and what you do. It's about extending the duration of the fast as much as you can, so that it remains compatible with your diet, and not the other way around. And this brings us back to thiskey characteristic of our biology, which is that what we eat when we eat, when we exercise, when we see light, is about establishing a context or a set of conditions in the brain and the body.

So it's not so much about the activities you do. It's about the activities they do and their relationship to each other over time, and in this way, it really beautifully highlights the way their biology interacts throughout the time the light goes down. When you are going to wake up, when you are going to sleep, when you eat, it will determine when you are going to wake up, when you are going to be asleep. And when you eat will also determine when you can remove waste from your brain and body and repair the various cells and mechanisms in your body, when you can reduce those inflammatory cytokines throughout your body.

And this is really the beauty of time and diet research, which is, it's not really about restricting diet. It's about accessing the beauty of the fasting state; There are now other ways to eliminate blood glucose that involve supplements or prescription medications. These are so-called glucose disposal agents, glucose disposal agents, such as metformin, which is a prescription drug, or berberine, which is an over-the-counter substance, will lead to very dramatic reductions in blood glucose. And then they shift you from a fed state to a fasted state. And I know many people who take berberine before eating meals that include a lot of carbohydrates, for example, as a way to eliminate glucose.

Now I have tried berberine before. And what I can tell you is that if you take berberine, which by the way is very similar to metformin, its effects are almost identical to metformin, but it is much less expensive and is sold without a prescription. If you take berberine and you haven't eaten carbohydrates, many people, including me, experience a terrible headache, you become hypoglycemic because it is a glucose-clearing agent. So if you're going to experiment with things like metformin, berberine, or the like, you have to be very careful not to wipe out blood glucose, which is already low.

And the dose response varies greatly from individual to individual. And there is a strong circadian component. So if some people react very well to berberine early in the day, but find that later in the day, it gives them extreme headaches, the opposite is true. So, I would caution you that when exploring things like berberine and metformin, you should expect to experience a number of physical and psychological effects that may work for you, may be great for you, but also may not be. Nowadays, there are several continuous glucose monitors available commercially, I have tried one of these, it involves placing what is essentially a patch with a small needle that goes into your skin, which continues to continually, excuse me, monitor your blood glucose. .

And you can watch it on an app on your phone and learn a lot that way about how different foods impact increases in blood glucose decreases. If you are experimenting with berberine or metformin, you will be able to see how they affect your blood glucose. You can see how exercise affects training or otherwise affects blood glucose, excuse me again, it is very difficult to assess blood glucose without a continuous blood glucose monitor, and if you are not using one you will be relying primarily on data subjective. Things like, oh, I feel like I have low blood sugar or I feel shaky.

Like I have high blood sugar or I'm shaking because you have low blood sugar. So I have to say that glucose-clearing agents that involve walking or moderate or intense exercise will be much easier to titrate and adjust the levels of the things you're going to take, where you have to adjust the dosage. And then once you ingest a certain dose, you're good to go, at least until the effects of that particular compound wear off, that doesn't mean those things have no use. It doesn't mean people aren't using them because a lot of people do, but they are potentially a very sharp blade that is double sided.

So I encourage you to approach them with caution. If you decide to do so, it is worth thinking about what the state of low blood glucose is and why it is beneficial, as well as why it can cause headaches. And in some cases the effects of other hormones can also be adjusted: when fasting, several different proteins that are expressed in cells undergo changes in their expression. We talked about this before: when we fast, we tend to reduce the activity of a particular protein called MTOR, a target of rapamycin in mammals. MTOR is very active in cells as they grow.

Thus, throughout development, it is also very active in cancers of various types. MTOR needs to be what is called phosphorylated. If you don't know what that means, don't worry. But phosphorylation is a way in which certain proteins are altered so that they can actually be functional within cells, MTOR is associated with the growth of cells of all types, healthy and unhealthy. When MTOR is phosphorylated, there is a marker called PS6, so MTOR phospho is expressed as PM6. If all this escapes you, don't worry. Phospho MTOR and PS6 are reduced on an empty stomach. Now this makes sense.

If you think about it, because eating and growth are associated with each other, fasting is not necessarily anti-growth, but it is not pro-growth, and when we fast, we see increases in cells of things like AMPK, sirtuins, things such as transcription factors such as FOX-O, ATF and ketones or ketone bodies. You may have heard of the ketogenic diet. What's the point of all this biochemistry? It's not, they just bombard you with a bunch of cell biology and biochemistry. That is, we have cell growth pathways involving MTOR and PSX, and we have cell repair and contraction processes associated with AMPK, the so-called sirtuins, which Dr.

Davidson Claire of Harvard and others are famous for discovering and understanding. things like AMPK, these two different divergent pathways of cell growth and breakdown and cell repair and, by breakdown, I mean autophagy and actual removal repair. These can be triggered by being in a state of fasting or eating. So I would like you to think about the eating state, not just eating, but having recently eaten or fasting state, meaning high blood glucose and either you have recently eaten, or you are currently eating, or drinking calories. It's that when you eat or don't eat, when you're fed, when you're fasting, you're promoting cell growth of all kinds or you're promoting cell repair and elimination of all kinds.

And again, it's about setting conditions in the brain and the body. It's not so much about when you eat foods A or B, but rather it leads to increases in MTOR, whenever you eat any food, no matter if it's fat, protein, or carbohydrate from plant or animal sources. You are predisposing your system towards a biochemical state of cellular growth. And every time you haven't eaten in a while or your blood glucose is low, you're predisposing your system toward a basement repair state. And that's why people who don't have any blood glucose regulation problems take things like berberine as glucose, disposal agents, or take metformin.

I'm not necessarily suggesting you do that, but it's because those things mimic fasting. They create situations in the body that promote things like AMPK, sirtuins and others to push your body and your system to go on a repair path, even though you ate an hour ago, along the lines of health benefits. of intermittent fasting, there is good data showing improvements in the gut microbiome and, in particular, in the treatment of irritable bowel syndrome and other forms of colitis over time, restricted feeding, which means that restricted feeding over time seems to be able to help people with those conditions, following the general parameters that I laid out before the eight hours and so on.

Why and how, well, through intermittent fasting, which affects the expression of these various clock genes, and because the clock genes affect the mucosa that lines the mucosal lining of the intestine, it seems that intermittent fasting can reduce the amount of so-called lactobacillus that is present in the intestine. And the lactose bacillus, at high levels, is correlated with several different metabolic disorders. At the same time, time-restricted feeding appears to improve the proliferation of some of the gut microbiota, such as Acetobacter and some others that promote a healthy mucosal lining and promote better overall gut function. These are pathways that have already been established, and it appears that intermittent fasting is not only modulating these processes, but is actually having a direct effect on the mucosal lining in a way that supports a healthier gut microbiome.

Therefore, it should be no surprise that many people experiencing intestinal problems benefit from restricting their eating period to approximately eight hours each 24-hour period. The other very interesting finding about intermittent fasting is one of the main health problems these days is the proliferation of the so-called non-alcoholic fatty liver disease. Approximately 30 years ago, nonalcoholic fatty liver disease was extremely rare to see clinically. Except in alcoholics, fat deposits in the liver are harmful. It is essentially a liver disease. Today, children and adults have nonalcoholic fatty liver disease. Some of these people are obese, some are not, but it is a serious health problem.

And their number is growing all the time. A recent study that was published in Cell Reports Medicine just a couple of weeks ago tested the hypothesis of whether or not the gut microbiome or so-called brown fat tissue is affecting liver health. And in particular nonalcoholic fatty liver disease. The short conclusion of this study is that, contrary to what was previously thought, the gut microbiome, although very important for other processes in the body, does not appear to be related to this non-alcoholic fatty liver disease. This is surprising to people or should be to those who have followed the gut microbiome literature;

However, brown fat, which is a healthy fat that we have between our two shoulder blades and in the upper part of the neck, does not tend to form. They are fatty-type fat pads, but they sit deep in the skin, but they create a thermogenic effect on the body that is useful for reducing the amount of other fats, the type of fat we are most used to thinking and talking about. white fat and pink fat which is subcutaneous fat around the abdomen, etc. Brown fat appears to have a direct correlation with the lack of nonalcoholic fatty liver disease.

What this study showed was that in people who have reduced concentrations of brown fat, there is a greater chance of having non-alcoholic fatty liver disease. Now the good news is that brown fat reserves can be increased. And again, this will not create brown fat. This will create greater thermogenesis and actually make people leaner and brown fat has other important positive effects. Now this is interesting because cold exposure for one to three minutes, two to four times a week, or maybe even 10 minutes, two to four times a week, can increase brown fat stores. Additionally, time-restricted feeding has now been linked to the density of stored brown fat.

Therefore, time-restricted feeding also appears to positively increase brown fat stores, likely due to the way brown fat stores relate to epinephrine and adrenaline, which tend to increase when we are fasting. What does this all mean? This means that, for the sake of liver health and for the sake of reducing, or perhaps preventing, or even potentially, I want to stress that it is possible to reverse non-alcoholic fatty liver disease, time-restricted feeding also seems be beneficial. Many people are interested in optimizing their hormones, and as we mentioned earlier, insulin is a hormone and time-restricted feeding seems to have very positive effects on overall insulin profiles, etc., but every time you mention hormones, people It immediately seems Let's move on to the sex steroid hormones, testosterone and estrogen, because they do indeed have powerful effects, both short and long term in terms of our physical and mental health and performance.

There is at least one study that has explored the effects of time-restricted eating on performance, athletic performance, immune function, and body composition. This was a study by Mauro, et al, which was conducted on elite cyclists. That's why I want to point it out. It was a randomized control trial, but what was really cool about this study is that it explored a number of different hormonal parameters in people who were using time-restricted feeding or who had a longer feeding period.dragged on. And they followed everything very carefully. And the amount of food they ate was actually quite substantial, 4,800 calories, so that's a lot of calories, but of course, they were very active and they measured a number of different things related to VO2 max, etc., performance. and overall performance in what they did on the bike is not the point I want to emphasize here.

Although there were some positive effects on your performance related to time-restricted feeding, the point I want to talk about relates to things that presumably relate to most, everyone, which is the effects on things like glucose, thyroid , hormones, testosterone, sex. , hormone, binding globulin, which can bind testosterone and prevent the so-called free form of testosterone, which is the one that has the most actions in the brain and body. And the main conclusion of this study was that time-restricted feeding of the same amount of calories as in the so-called control condition, okay, the same calories, but compact throughout the 24-hour cycle up to a feeding period of eight hours or allowing them to eat over a longer feeding period led to significant decreases in free testosterone.

And I think a lot of people will be surprised by that and think, well, then maybe time-restricted feeding isn't for me. Of course, there are a number of important considerations, one being that the decrease in free testosterone is significant. It will also depend on where people start. So if someone already has modestly lower testosterone levels and it drops by 10 or 20%, that could put them in a state of poor performance and well-being, whereas if someone has higher testosterone levels, a decrease will necessarily cause that. That's why it's important to keep that in mind. That's why I'm always such a fan of people who do blood work and know what's going on with them under the hood, a big change in hormonal profile was cortisol.

The so-called stress hormone cortisol is of course also released naturally early in the day in a healthy way to wake you up and promote alertness, but you don't want your levels to be too high or have cortisol spikes at the end. of the day. day, that actually correlates with depression and a host of other unvisited things. You would have thought that by restricting a feeding window to a particular time each day, these hard training cyclists would have experienced increases in serum cortisol and in fact the opposite was true. They had significant reductions in serum cortisol as a consequence of time and restricted feeding.

I should mention that there were also significant reductions in serum cortisol in the control group, but not to the same extent. And the two groups differed significantly from each other. Now this is important because if you only look at one hormone, testosterone, you would say, okay, based on this data, time-restricted feeding is significantly reducing testosterone levels, even though the calorie count is quite high. and remains constant throughout the year. study, but in fact, because cortisol is lower, it may mean that the effects of testosterone or reduced testosterone are offset. And that's because cortisol and testosterone are always kind of in a dance in terms of cortisol, greatly inhibiting the effects of testosterone and vice versa.

That's why it's interesting and important to look at the full gallery of hormones. And they looked at a series of hormones. They looked at other inflammatory markers. These did not increase. This is not surprising if you remember the Satchin Panda study from 2012, this pioneering study on time-restricted feeding. They saw reductions in stress hormones and inflammatory markers over time by restricting the mice's diet. And here it seems that this also happens in humans. So the bottom line is for the sake of hormonal health, time-restricted eating is compatible with quality hormonal health, even in high-performance athletes. Based on everything we know and what we've discussed, I wouldn't suggest people restrict their eating window. to less than eight hours, especially if they train hard on a regular basis.

And it's not just athletes who should pay attention to this: when we work very hard, when we are psychologically stressed, when we study for exams or have conflicts with someone on a regular basis, this creates stress in the body that is very similar to that of physical training, The body and brain do not distinguish between physical stress and mental stress, it is all nervous system. Remember it's just cortisol and adrenaline. There's no special hormone just for physical stress versus psychological stress, so again, when thinking about what kind of eating window will be right for you, we go back to this eight-hour period that seems more or less flexible for most. the conditions, even the high ones. -Elite athletes.

And I would say just by logical extension, even for people who have a lot of stress in their life. And I personally wouldn't suggest that people who have a lot of stress in their life, where there is potential for stress in their life, shorten their feeding period to much less than eight hours, because then they would be expected to start increasing some of the feeding time. inflammatory markers. It would increase stress hormones and decrease things like testosterone and estrogen, some of the sex steroid hormones. Again, it's all about context and the eight-hour window, it's not sacred, but it seems to be a really useful guide to extracting the great health benefits, of which there are many, which we've talked about since the time of fasting. intermittent. , restricted feeding.

And yet it might be compatible with decent social schedules and maintaining hormonal health accordingly, for women trying to maintain ovulatory cycles or for couples trying to get pregnant. I think it's also important not to create too short a feeding window. The relationship between diet and body fat stores, glucose, leptin and hormones is well established. And we can summarize it very easily here, although I've already done several episodes related to this on how to optimize hormonal health. But basically we hit puberty when there is enough food and enough body fat for the body fat to send a signal to the brain called leptin.

That's a hormone that comes from body fat signals to the brain to trigger puberty, that's puberty, but even in adult women who are menstruating, there needs to be enough leptin signals to the brain to maintain ovulation because of the way the brain communicates with the pituitary and ovaries. Similarly, for men who do fasting or extreme exercise plus fasting, we now know that it reduces testosterone; its impacts are not exactly clear; However, if you reduce your food intake too much, either in total calories or duration, you will suffer a drop in sperm count and fertility. will fall.

And this makes sense. The body communicates with the brain whether or not conditions are sufficient to reproduce and, presumably, and hopefully, support the health and well-being of those offspring. So there is a logical link between body fat and diet, how much food is available to you and for how long it is available to you, and the signals in the brain that enable reproductive success. There is some data that points to differences in the effects of intermittent fasting in men and women. Those data for now only come from mice, that study was recently published by Satchin Panda, we are still waiting for studies in humans.

Some people don't do well with intermittent fasting either in terms of mood or hormonal health. Therefore, everyone must determine for themselves whether having a restricted feeding period is good for them. How long should that time-restricted feeding window last? I think eight hours is a good minimum to stick to based on everything we've covered today. And for some people, time-restricted eating won't be compatible with hormonal health; For them, eating more meals spread throughout the day, presumably smaller meals, the same caloric intake will be more beneficial for their hormones. This is something that will be individual and will have to be determined on an individual basis.individually.

However, if you are going to try time-restricted eating, I want to remind you to take a period of three to seven or, ideally, 10 days to transition, not just go from eating three meals a day spanning 6 :00 a.m. m. to 10:00 p.m. m. and suddenly move to an eight-hour feeding period, but instead of reducing that feeding period by about an hour per day, you will allow your body's hormonal systems, including the leptin and hypocretin orexin, system, which are systems within the body, which send signals to the brain, that food is about to arrive, allowing those systems to adjust so that you are not overwhelmingly hungry, irritable, and throwing your entire hormonal system out of balance. .

I keep coming back to this eight hour eating window and I want to provide a little more foundation for it. And just to encourage that it's not completely arbitrary. The extensive review I mentioned above presents a number of studies that have used this eight-hour feeding period, but there is one study in particular that I would like to highlight mainly because I don't expect people to delve into the entire reference list in the other review. . And this is a study that was conducted between Satchi Panda's lab and Krista Varady's labs. This is a collaboration. The study was conducted in humans and is titled Effects of Eight-Hour Restricted Eating on Body Weight and Metabolic Diseases, Risk Factors in Obese Adults, excuse me.

And this study basically showed, I'll just read the conclusions, that eight-hour restricted eating produces mild calorie restriction and weight loss without counting calories, so that's the key, right? These people do not count calories in any way by simply following an eight-hour period. They eat fewer calories than they burn and clinically reduce blood pressure. So I mentioned the study, not because there aren't many others that include the eight-hour feeding period in humans as well, but because the eight-hour feeding period has been tested in obese and non-obese adults. And there are even some studies in children. So this eight-hour window seems like a pretty good rule of thumb and sort of an anchor around which each of us can think about incorporating time-restricted eating.

Of course, there are other eating patterns. And although some people have fasted longer than 24 hours, 36 hours or more on alternate days, that is, eating one day, not eating the next day or, in some cases, eating one day and consuming very few calories, 500 or 600 calories the next day. The day has been tested. Some studies have also looked at eating a sort of maintenance level of calories for five days, and then taking two days and fasting until the end, or eating very few calories, you know, 300 or 500 calories. In fact, there is something of an online community of people who are exploring longer and faster to try to offset dementia or reverse the effects of dementia;

So far, at least to my knowledge, there is no quality peer-reviewed clinical study. about that still for the sake of dementia, although I look forward to those studies, and if anyone knows of them, send me a link in the comments. But alternate day fasting has obtained the so-called safe health certificate. This has been written to mean that people did not suffer bone loss, they did not suffer any major detrimental effects. It appears that it can create significant weight loss and may help obese people because it can reduce resting blood glucose, and fasting every other day in many cases can produce faster effects on weight loss and lowering blood glucose. blood glucose than time-restricted feeding.

However, for most people, fasting every other day will not be feasible. They simply won't be able to do it for a long period of time. And what hasn't really been done is the follow-up to see if people who fast every other day or five days of eating followed by two days of fasting, whether or not that leads to a rebound in weight gain, whether or not not that it causes a rebound in blood glucose, etc. So for now, the eight-hour feeding window and time-restricted feeding seem to be the most tested, supported in animal and human studies, and which I think most people should orient themselves around if they are considering starting time-restricted feeding.

It's also a little difficult to imagine how a major exercise or work program could be included in fasting every other day. Remember, in any study, people are usually compensated, or at least incentivized in some way.way to join the study. This is one of the main problems I have with any study that says that three or four different diets are essentially the same in terms of their ability to produce weight loss. Adherence is very different in the outside world, where you don't have a researcher monitoring you and where you don't log all your food. Most people don't do that consistently.

And we can take a little bit of a neuroscientific perspective on this to try to come up with what the best type of organization of an eating plan, or if we wanted to call it a diet, would be for you. Many people find it easier to simply not eat during certain periods of each 24-hour cycle than to eat smaller portions; Portion control is very difficult for some people, for others it is manageable, but people liked it. I don't eat half the croissant. I don't think it's a real thing, it's not, it's not available to me, I should say.

Now, of course, I could eat just half a croissant, but I realized that when I eat the croissant, because they are so delicious that they create an increase in blood glucose, an increase in other hormones and chemicals associated with eating delicious foods. , very tasty food. And it actually takes a lot of work for me to eat half the croissant. There's something so much more satisfying about eating the whole croissant. And in fact, there's something quite satisfying about not eating the croissant at all. And just knowing that I can eat the whole croissant later. That's me. Other people find that they have no problem with portion control and that, for them, eating small pieces of food throughout the day is what puts them in the right psychological and physical state for work, etc.

And I mentioned work and mental focus because one of the aspects of fasting that has attracted many people to time-restricted eating and fasting is the mental clarity they gain. First of all, they don't have to think about when they are going to eat because they know when their eating window begins. They also don't have to think about regulating their behavior because they already know when they are going to eat and when they aren't. Whereas when you restrict portions, you actually have to make decisions all the time. You know, and I think I like that a lot of people decide, well, you know, that's exactly half of it?

Or could I have liked another mistake on the croissant? This kind of things. I don't deal with food. That's why I like a time-restricted feeding period. I know what I'm going to eat because in my case I use a feeding window of about 10 hours and I'll eat the whole croissant. I just don't have to think about it, now, the food choices you make within that eating window will of course also be very important. Certain foods will increase blood glucose, so you will become hungrier and hungrier. Others will maintain a lower blood glucose level and allow you to be more controlled in the foods you eat.

Those are all individual considerations that deserve their own full episode. But I do want to point out that the advantage of time-restricted feeding is that it involves a lot of the decision-making in the brain. The so-called go-no-go circuits of our basal ganglia, if you want to know these areas that control them. Any time we have to restrict a behavior, that is called no-go. Every time we engage in a behavior, go or no behaviors require a lot of what's called top-down control, and it's very metabolically demanding. And so, time-restricted eating allows you to get away from all the no-go negotiation you have to go through when you have to restrict portions.

So I think this is one reason why a lot of people have gravitated toward time-restricted eating and why for people who don't want to have to think about all that, it's very simple. One of the hottest topics out there is whether or not to give equal amounts of caloric intake and equal amounts of activity and equal amounts of nutrients, etc., whether or not you restrict eating to a particular window biases greater weight loss. towards fat loss. versus the loss of other tissues, because of course when we lose weight, we can lose it from any number of different storage sites within the body: muscle water, glycogen or fat.

This is such a hot topic that I almost don't want to get into it, but I will anyway, because there are data that are very interesting. This is covered in the review I mentioned above, which describes how if people follow a restricted eating schedule for long periods of time. So over 60 days or more, there are some metabolic changes in the way people metabolize energy that seem to cause the system to lose more fat compared to burning other tissues when you're in a state of caloric restriction. And I mean when you're in a state of calorie restriction, because there's really no way to game the system, there's no way you can take in a lot more calories than you burn or excrete, when I say excrete, you know, certainly not.

I suggest this, but, you know, bulimics and other people who have eating disorders use laxatives to quickly remove food from their system so that it can't be converted into fat or other forms of energy. In that case, it is a very pathological situation, but in general, the calories in versus the calories out, as I mentioned before as this type of fundamental element, but in states of caloric restriction, that is, an intake lower than that of maintenance, time-restricted feeding does not seem to buy us more energy burned to compensate for that fat deficit and the way it achieves this is very interesting.

It turns out that it drives greater fat loss by increasing liver lipase. This is something called LAPC, liver hepatic medium and lipase, which whenever you hear ASC means it's an enzyme. So it seems to increase liver lipase. So it increases the enzyme that metabolizes fat for lipolysis and energy production and reduces something called CIDEC, CIDEC. which is an inhibitor of lipolysis associated with lipid droplets. That's a mouthful, no pun intended, but what CIDEC really is is this lipid droplet-associated molecule that can inhibit lipolysis. So long periods of time, restricted feeding, that is, an eight-hour feeding period or a 10-hour feeding period that is obeyed for several months or more, appears to allow the system to shift toward burning more fat or, rather, use a higher percentage of fat when you are in a calorie deficit. .

Now, I doubt this is going to solve the real barbed wire, almost hairball, and ridiculous debates online about whether or not time-restricted feeding is better than another feeding schedule. Look, I don't think any particular feeding schedule is sacred. If you are undercaloric, that is, you burn fewer calories than you ingest, you will lose weight. But the data seemed to point to the fact that if you go on restricted eating for a fairly long period of time, and you maintain that, you're increasing these lipases that increase the energy use of fat lipolysis, and you're decreasing the amount of lipids. droplet-associated lipolysis inhibitors.

So you're eliminating rest and you're hitting the accelerator on fat loss. I think this logically points to a case where using a time-restricted diet with a subcaloric intake seems to be, at least in my opinion, the most scientifically supported way to ensure that a significant portion of the weight one loses comes from body fat. stories. Any discussion of fasting would be incomplete without a discussion of what is broken and what is not broken. However, there is no black and white answer to that question, and you should immediately understand why because eating and not eating is not the same as eating and fasting.

It depends on when you ate, how much you ate, and where you are in your circadian cycle. In fact, we can come up with a simple answer as to whether something breaks the fast or not. Now, the technical way to do it would be to use a continuous glucose monitor and eat small pieces of food, of different types or large amounts of food, of different types, and measure the blood glucose, because ultimately the blood glucose blood is the reading of whether or not your system is in a fed or fasted state. Of course, there are other parameters as well, but that is the dominant one insofar as the scientific literature says that drinking water will not break the fast.

Drinking tea will not break your fast. Drink coffee, as long as black coffee does not break the fast. Caffeine in pill form will not break your fast. There are other things that will not break your fast. For example, eating a peanut on a deep fast will not break the fast; Eating a whole handful of peanuts might not even break your fast if you are in a very low glucose state. However, if you just finished a meal that included carbohydrates, or if it was a very large meal of any kind an hour ago, yes, in fact, eating a peanut could break your fast.

So it's all contextual, that's what's really important to understand, unless you're going to use a continuous glucose monitor. And unless you're going to use a continuous glucose monitor and set an absolute numerical threshold for what breaking your fast is. I think there are some simple rules we can follow. First of all, anything that involves sugar in particular, simple sugars, can potentially alter your fast. And in fact, there's a study on this, which shows that if people eat even a gram of sugar after dinner, if they have a full meal at dinner, that can alter the expression of some of the circadian genes related to sleep. fasting and sleep. and sleep-related fasting.

That's pretty extreme, it's almost scary to think about, but that's how sensitive our system is. If we already have somewhat elevated blood glucose from a meal we ate approximately an hour ago, while if we have run for an hour or have trained hard, high-intensity workouts, and we have not yet reached the beginning of our so-called feeding window, what? Will eating a small amount of food get us out of that fast? Well, it depends on what the food is. If it's mainly fat, probably not, nowadays many people talk about the so-called fat fasting, fat fasting as a way to overcome the strictness of eating or not eating as a black and white rule for the eating window. versus non-feeding window.

Therefore, some people will eat medium chain triglycerides, so-called MCTs, or eat fats only until their official eating period begins. This is how the negotiations that people carry out tend to be. But that, of course, won't raise blood glucose and insulin as much as carbohydrates do; proteins will have a kind of intermediate effect. And as I mentioned above, ingesting carbohydrates with some fat will tend to blunt the glucose spike and extend the time during which glucose is released. So we can't really say that food X or drink X breaks the fast; However, at the extremes, we can say that, for example, if you drink a can of soda, unless you just ran an ultramarathon, you are breaking your fast, okay, eat a slice of pizza.

You are breaking your fast, eating purely fat, maybe, probably not. If you have been fasting for five hours or more, fast strictly for five hours or more. Then you can start to see where there's a lot of wiggle room and it's very contextual. And that's why any post you see or any information you see about something that does or doesn't break your fast, doesn't put it in the context of when was the last time you ate and what you ate and your activity and your time within the schedule of the fast. 24-hour circadian clock, it's kind of a pointless discussion, so in general I think what's really helpful if you're not going to use a continuous glucose monitor is to try to be pretty strict about when you start your monitoring window. eating and when you stop it and as time goes on and you establish a more regular routine of eating certain types of foods and not others that are right for you because, as I have emphasized before in this podcast, and I will continue to emphasize that the ketogenic diet works very Well for some people, the vegetarian ketogenic diet works very well for some people and the carnivore diet works very well for other people.

Some people are omnivores, some are carnivores, and some are vegans. That's all great and fine with me. Each one has to establish what is right for him; Nowadays, we have really overlooked the discussion about foods of a particular origin or type, animal or plant origin. But the same rules apply within this thing we call intermittent fasting or time-restricted eating. So what breaks a fast will depend on what you want to eat or what you are willing to eat. That's a totally different way from when you eat. But as we've established, when to eat is of vital importance, some of you are probably wondering if artificial sweeteners or non-artificial plant-based sweeteners like Steviabreak the fast, this will vary a little.

And I have to say that the data on this is somewhat contradictory. There is evidence that when people ingest artificial sweeteners, it can create a transient increase in blood glucose followed by a transient decrease in blood glucose below baseline. This is thought to explain the increased hunger caused by ingesting things like aspartame and sucralose and the like. There aren't many good studies exploring sugar-free plant sweeteners, like Stevia, and even things like monk fruit, which is a separate category in itself. There aren't many studies on this. I think most people need to establish this for themselves. The best way, of course, would be to use a continuous glucose monitor to enter a fasting state for one or two hours, or perhaps have been fasting overnight and then ingest Stevia in the form you want or coffee in the form that you want. any way you want with sucralose or aspartame, etc., leaving aside the discussion about the effects of these things on the gut microbiome, which is a completely different topic.

I think it's fair to say that in moderation, sugar-free plant sweeteners like Stevia in particular, Stevia seemed to have minimal impact on overall blood glucose when considered over a fairly long time: aspartame, sucralose, and saccharin. I think we can say more or less the same thing, but as soon as you get into a discussion about this, you also have to get into a discussion about some of the evidence published in Nature and other excellent journals that now point to the fact that when consumed in excess, not when consumed in moderation, but when consumed in excess, can have some detrimental effects on the gut microbiome.

So do artificial sweeteners break your fast? Depends the quantity depends on the type. And overall, I think you're probably fine as long as you don't consume them too often; However, some people simply by trying something sweet feel an increase in appetite that makes it difficult for them to fulfill it. the feeding window. And that's why you can imagine that a really well-controlled study on this would be very difficult to carry out. And I'm not really sure it's worth our tax dollars to design and conduct a study like that because there would be a lot of individual variation in terms of discipline in adhering to the eating window, regardless of whether people experience gains or falls or not. in blood glucose, how that affects them, whether they're exercising or not.

It simply becomes an infinite variable space, as we say in experimental science. So you really have to determine that for yourself, but I don't think we can fairly say that artificial sweeteners break the fast. I think it would be incorrect to say earlier that we were talking about glucose disposal agents, both behavioral and compound, such as metformin and berberine, and in fact, cinnamon is even a mild glucose disposal agent. In fact, it can lower blood glucose; Lemon and lime juice, believe it or not, can lower blood glucose. You may have experienced this before by eating something very, very sweet and almost feeling overwhelmed by how sweet it is, especially if you're not used to eating a lot of sugary things.

A quick remedy for this is actually half a lime or half a lemon squeezed into juice and drinking it just for the taste and the fact that it will lower your blood glucose. You will notice that this effect disappears almost immediately, that is not magic. Those are the effects of acidity on blood glucose levels. So there are a number of things that can adjust blood glucose, they're not necessarily clearance agents, they don't remove it from the bloodstream in the same way that berberine or metformin would, or high intensity exercise in the appropriate moments. of the day I would.

But there is one thing in particular that one can ingest that can help manage psychologically and performance-wise during the intermittent fasting portion and carry it into your eating window. And that is salt. I've talked a little bit about this on the podcast before, but because neurons use salt, sodium, potassium, and magnesium, so-called electrolytes, to perform their chemical and electrical signaling magic, everything you do depends on the chemical. Electrical signaling and all that chemical and electrical signaling requires electrolytes in one form or another. Neurons function by passing ions like sodium in and out of their cell membranes, I should say, across their cell membranes to be exact.

Many people find that the kind of lightheadedness and shakiness that comes with having slightly low blood sugar can be offset by taking about half a teaspoon of sea salt, or even just a pinch of salt, putting in a little water and drinking it Some people find that because of the glucose-lowering effects of acidity, if they feel a little shaky and not well, they put a little lemon juice in water and drink, that lowers their blood glucose level even further. . So today there is a common practice discussed on the Internet: waking up drinking some water with a little lime or lemon juice with a pinch of salt.

I think that pinch of salt is a good idea. What are you doing, how are you compensating for all this? Well, salt water actually has a mild effect as a glucose disposal agent, but it has a stabilizing effect on blood volume. And so, because sodium brings with it water and the so-called osmolarity of blood in the body depends on the salt levels in the blood, brain and body. Many people feel shaky. They feel dizzy. They can't concentrate. They think they need sugar or food, but what will really remedy that is a little salt. And I know several people who have incorporated this practice and have written to me saying, oh, you know, if I just put a little bit of salt in a little bit of water, they may or may not include the lemon or lime juice.

They immediately feel better and find that it's actually pretty easy to get started, just wait until the feeding window starts. This is especially true for people who consume caffeine because when they ingest it, they actually excrete a lot of water. It has a diarrheal effect. And with that water goes the salt. So it actually causes you to excrete sodium. Now, the role of sodium in blood pressure and hypertension is a rather controversial scientific journal. A major scientific journal published a special issue on salt a few years ago, talking about research on hypertension and, indeed, people with chronic diseases.

Hypertension or high blood pressure or very high blood pressure in particular, care should be taken not to ingest too much sodium. But for most people, sodium intake, as long as they drink enough water and don't have chronic hypertension or high blood pressure, is actually beneficial. Now, that doesn't mean you should drink sea water, it doesn't mean you should overuse salt, but many people find that they can control their physical and mental state and even feel really fantastic, with real mental clarity, and really enjoy themselves. its fast when they are ingesting enough salt. And all you really need is a small pinch of salt, ideally Himalayan or sea salt.

If you want to give it a sophisticated touch, table salt would be good. And just drinking that in a little bit of water, maybe with lemon or lime juice to offset the flavor a little bit, can really stabilize the nervousness and stabilize the mind, and you may also notice that it can offset that agitation and craving and appetite. where you can't. Imagine spending another five minutes before eating something and suddenly you feel good. And that has to do with many of the blood volume effects caused by eating salt in the right amounts. In other words, sometimes you think you need food, but what you really need is salting and salting can make you feel better right away.

I'd like to mention some great zero-cost resources as well. If you are going to explore time-restricted feeding, or perhaps if you are already doing time-restricted feeding, I have no affiliation with any of these options. The first is the website I mentioned before, My Circadian Clock, which is the website hosted by Satchin Panda and his colleagues. There are many resources where you can log your food consumption, learn about time-restricted eating, all the science, ongoing studies, etc. The other is the so-called Zero application. That makes it very easy to mark when your eating window starts and when your eating window ends, so marking when your fast starts and when your fast ends, where you at least start the beginning of the non-feeding period.

Status, as we might more accurately call it, is a fantastic app. I have used it from time to time. I don't usually use it continuously because now I'm used to eating at a certain time of day. But every time I changed that window, for example a few weeks ago, I started moving that protein intake throughout my eating window earlier in the day. And because that requires some attention on my part, because I'm not used to doing that. I've been using the Zero app and I quite like it. It tracks your progress and gives you averages and you can see how many other people are fasting again, free of charge.

I don't actually know who owns that app, but I think they've done an excellent job. The interface is really fantastic and as far as I know it's available for Apple and Android, but at least it's available for Apple phones, which is the type of phone I have. So check them out, My Circadian Clock. Just put it in Google and you will find it. And the Zero app, both excellent zero-cost resources. In a moment I would like to review the parameters of an ideal eating schedule for you and provide you with variables that you can adapt to your lifestyle and preferences.

There are a couple of things that I would put in the FAQ category, somewhat strange, but still worthy of discussion. For example, people have asked: will brushing your teeth with toothpaste break your fast? I think unless you're swallowing the toothpaste, no. Now, if you really want to run out and get a continuous glucose monitor and brush your teeth, you can test that, but no one has asked you if half a glass of wine after dinner, a couple of hours after dinner, will break your fast. . Absolutely. Absolutely it will be. And it's been shown to do that based on a gram of sugar, kind of a creepy or creepy effect that I talked about before, creepy and creepy, because it just looks like a gram of sugar.

How could he do that? But these are metabolic processes and are very sensitive. After meals, a few months ago I did an experiment using a continuous glucose monitor. And I was surprised when I discovered that entering a sauna increases my blood glucose level quite a bit. In fact, it increases as much as a meal. And then it tends to drop back to baseline or even slightly below baseline afterward, when I talked to people about this, someone said, oh, it has to be that the continuous glucose monitor was being disturbed by the heat in the sauna. . Actually, that is not the case.

It turns out that when you enter a sauna, because you become dehydrated, you are losing water, I didn't drink water and you are throwing away a lot of water. In fact, the concentration of sugar in the blood increases. And I actually posted this data in a social media post on Twitter, and people were a little surprised to see how much a sauna can increase blood glucose. Now I practice timing, restricted eating, and intermittent fasting. I'm not very strict about it. I use sort of an eight to ten hour window, either early in the day or at the end of the day.

I saw this effect of the sauna, personally, the effects of the sauna on physical and psychological health are valuable enough to me to continue using it. I'm just not worried about this increase in blood glucose, to the point that I'm going to eliminate the sauna. I like to use the sauna three or four times a week before bed, so I use it an hour or two before bed. And yes, it actually creates this big spike in blood glucose that then drops based on the change in blood sugar concentration. I'm just not going to worry about it, if you're worried about blood glucose spikes then you might be worried, but in my case, it was one of those things that was interesting and worth it. of discussion.

I thought about it because I was a little surprised, although it makes a lot of sense why that would be the case, but at the end of the day it literally makes sense for me to go into the sauna. Well. Now you've heard a lot of science. You have heard many examples, even some anecdotes, and we are going to propose the restricted eating schedule, also known as intermittent fasting, ideal for you. And when I say ideal, I mean, what are the variables that are negotiable? What are the ones that are not negotiable? What is ideal for you will depend on the context of your life and what you are willing to do consistently.

So, first of all, we established it based on the discussion with Satchin, who is trulythe world's leading expert in this area, who knows the scientific literature on animals and humans better than anyone who wrote this incredible review. And whoever I asked that you don't want to eat food for at least I want to emphasize at least 60 minutes after waking up, second, you want to avoid eating any food of any kind, even one gram of sugar, remember, this is ideally one gram of sugar. although it would be too much for the two or three hours before going to bed.

He also mentioned that the ideal is to spend eight hours in bed. I didn't tell you that before. I saved it for now, but ideally you want to get those full eight hours of sleep, but just by being in bed for those eight hours and avoiding eating after you wake up for an hour and before you go to bed for two or three hours, you're starting to develop . the duration of this fasting period. He remembers that sleep-related fasting is particularly important because of the health benefits of time-restricted eating. Again, sleep-related fasting is especially important because of all the cellular repair processes that occur in the liver and gut, in the microbiome, in the brain, and throughout the body.

And because of the way that that coordinates the expression of clock genes that will then fade away and have many other positive health effects, including weight and fat loss. But aside from liver health, etc., a goal feeding period of eight hours seems to be the best feeding goal, at least from my reading of the literature. And when discussing it with shorter feeding periods, four to six hours, they tend to lead to overeating and potentially weight gain. The one-meal-a-day type of eating doesn't seem to do that, but those are special cases where most people can't stick to a one-meal-a-day schedule, at least not on a regular basis.

And it's not very compatible with most social schedules. Although some people can easily accomplish this, there are no solid studies exploring the benefits of one meal a day. So if you think that one meal per day has advantages for you instead of an eight hour feeding period, then by all means use the one meal per day approach or use a four to six hour feeding period and just Make sure you don't eat too much in that window. Remember that most people tend to miss the eight hour feeding window, they say eight hours, but they tend to eat outside of the eight hours a little bit on either side, so if your goal is an eating window than 10 hours, you may want to set it to nine hours or eight hours.

If your goal is six hours, you may want to set it to seven or eight hours. And this is based simply, I shouldn't say simply, it is based on thousands, if not tens of thousands of data points from human subjects that Satchin and his colleagues have collected. Regular placement of the eating window or feeding window, every 24 hours, is important. . You don't have to be absolutely rigid and neurotic about this, but you don't want it to slide on the weekends so that it starts two hours later and ends two hours later, a couple of days a week, because then you start to counteract many of the positive health effects that have been demonstrated with time-restricted feeding.

Remember that if you eat your food within a certain eating window, but that eating window shifts by a couple of hours, it is effectively like jet lag in your system. It's effectively like traveling a couple of time zones instead of eating there for a few days and coming back when you're not actually traveling, that's because of the way the food adjusts, the circadian clock genes. Now you can offset some of that by using light. And I've talked extensively about how to use light in previous podcasts, but again, early in the morning and throughout the day, expose light as safely as possible, ideally from sunlight, not through a window, etc. ., avoiding bright light in the middle of the night, extremely important to compensate for mood, metabolic dysfunction, etc., it is not by chance that Satchin's early work was one of the three co-discoverers of the cells of the eye, the called melanopsin cells that anchor the center of the eye. circadian clock.

So he was a pioneer in that field, which led to him being a pioneer in this field and so on. When should that eight-hour window be placed within each 24-hour cycle? Well, let's talk about the ideal ideal. If you really want to maximize all the health benefits of time-restricted eating, you should extend your fast around sleep on both sides. You would place it right in the middle of the day. It would be a time when you start eating, for example at 10:00 a.m. And you stopped eating at 6:00 p.m. An absolutely terrible schedule for anyone who wants to have anything resembling a normal life.

In my opinion, it's not really compatible with most schedules. Although some people might, maybe you and your family or your friends, you know, are having a late breakfast or a late lunch around 2:00 p.m. . And then you have dinner at six. And then, assuming you go to bed around nine thirty or 10:00 p.m. m., that will extract the maximum amount of weight related to body fat, metabolic factors related to aspects of time and restricted eating. Some people tend to fall into a category where they do better by putting that feeding window later in the day and providing it.

Don't run too close to your dream. Remember that you need a cushion for two or three hours before sleeping, where you do not eat anything in order to extract the benefits of time-restricted feeding. Well then start your feeding period at 12:00 pm. m. and finish at 8:00 p.m. m. Give or take a half hour or so day to day, it seems like a perfectly reasonable schedule to some people starting at 2:00 p.m. m. and ends at 10:00 p.m. m. :00 PM will be that time. Of course, you have to take it into account when exercising. If you exercise.

For example, I like to exercise early in the day if I run, or if I do any moderate or light intensity exercise, no matter what type of exercise it is, I have no problem waiting until my eating window starts around noon or even 2:00 PM. But if I do high-intensity weight training, for example, early in the day, or if I run sprints and I do it at 7:00 a.m. or at 8:00 a.m. at 11:00 a.m., I am very, very hungry and it is difficult for me to do other things, concentrate, etc. Now I'm not neurotic about my eating window.

As I mentioned before, I let it expand and contract a little around the eight-hour mark, and I feel perfectly free to do so as well. We're talking about ideals here, not necessarily practicalities, but other people find that they are very hungry when they wake up early in the day. If you are one of these people or someone who is really trying to emphasize hypertrophy or muscle maintenance, then it seems that eating protein early in the day is beneficial. Which can be more easily converted into muscle tissue. And at least one study has shown this. There is another study underway.

That's exploring this further for people who are really interested in hypertrophy and muscle building, then time restricted feeding is generally not your route. I mean, let's be honest. There are many people who eat four more meals a day, and they do so from 7:00 a.m. m. until 8:00 p.m. m. I realized that not everyone is overweight. There is an obesity crisis. Indeed. You know, the percentage of obesity and non-alcoholic fatty liver disease is just cosmic through the roof, at least in this country and also in other countries, this country refers to the US but also other countries.

But of course there are people who are trying to gain weight but don't want to lose weight or who are trying to maximize physical performance or hypertrophy or things like that. And of course time restricted feeding for them could be while I'm awake and eating. And I, you know, I take my hat off to those people and just say, you know, as long as you understand what you're doing and the burden that that puts on some of the other processes in your body, if that's right for you. , then by all means pursue that. Another thing we can add to this summary or key points related to time-restricted feeding is the use of glucose, elimination, agents and/or behaviors.

If you find that you have eaten too close to a time period when you would prefer to be fasting, that is when a brisk 30-minute walk or even a modest walk after eating can be beneficial; Drinking a little lemon or lime juice can help. lower blood glucose a little. And then there are things like metformin and berberine, even some supplements that combine things like berberine, cinnamon, which can lower blood glucose, and things like chromium and things that have a mild effect on blood glucose, But berberine and metformin are very high potency glucose disposal agents. And I mentioned earlier why you would want to approach them with the right level of caution and determine the doses for yourself and for some people, the doses will be zero milligrams and that will be ideal.

And then, of course, we discuss how to make sure you get enough fluids, particularly water and salt, especially if you use caffeine to increase your alertness levels, regardless of where the caffeine source comes from: coffee, tea, or not, which can cause sodium excretion and cause a kind of tremor, lightheadedness and feeling of hunger that may or may not be related to blood glucose. Some people really need to eat. I certainly wouldn't want to see people hypoglycemic to the point of being dangerous. Certainly, if you are diabetic, and indeed for all people, you should consult with your doctor when exploring any major dietary changes or additions or subtractions of anything, including supplements, but for most people, maintaining a relatively low or modest blood glucose level.

The levels will be quite healthy and allow all the positive effects of intermittent fasting to occur. And when you find that reaching that beginning of your feeding window is a challenge, ingesting sodium can often stabilize your system mentally and physically, and allow you to reach that window often without pain. And then as a final point, as I mentioned earlier, as long as they're consumed in low, no, or modest amounts, artificial sweeteners or no-sugar, no-calorie vegetable sweeteners don't seem to really affect blood glucose to the extent that, quote-unquote , it would take you out of your fast, but that, like fat fasting, is something that will be very individual and that you will have to experience for yourself and be able to recognize when you are fasting and when you are out of fasting, at a level subjective and not having to constantly check your blood glucose or do things like that can be beneficial.

And I think if you pay attention to the feelings associated with eating and after eating different types of foods in different amounts, and you pay attention to the feelings associated with fasting for long periods of time or short periods of time of having received enough light solar or having trained harder, not trained hard that same day, etc., you can do the most important thing, which is to start learning, evaluate your own system, run simple and safe experiments on your system in a way that allows you to really establish the ideal nutrition program for you, whether it is time restricted, eating, also known as intermittent fasting or some other nutritional plan.

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I hope you have learned a lot about metabolism, energy and health and how when you eat is as important as what you eat and last but not least, thank you for your interest in science.