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Dr Rangan ChatterjeeDr Rangan Chatterjee

The PERFECT TREATMENT For Diabetes, Weight Loss & LONGEVITY | Dr. Satchin Panda

To get 1 year's FREE VITAMIN D and 5 FREE TRAVEL PACKS visit If you have an existing health condition or are taking medication, always consult your healthcare practitioner before going for prolonged periods without eating.

Dr. Rangan ChatterjeehostSatchin Pandaguest
Oct 26, 20222h 4mWatch on YouTube

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Transcript

  1. 0:00 – 7:27

    Origins of Time-Restricted Eating and What Fasting Does in the Body

    1. RC

      I think it's fair to say that the research you pioneered in your lab is largely responsible for this phenomenon that we call intermittent fasting. Is that fair to say?

    2. SP

      Yeah. Uh, actually, that's the first time we... Exactly ten years ago, we published the first paper, and that was done in mice. And in mice, we did, uh, this experiment where we fed the mice for eight hours. They ate the same number of calories as the other mice, but they were completely protected from metabolic diseases. And we were surprised. So initially, when we published the paper, we were a little skeptical whether it would work in humans. But before we tried in humans, uh, other people tried it, and, and then it took off. We called it, uh, time-restricted feeding because that's the correct scientific term. Um, but now it's very popular as intermittent fasting, specifically eight-sixteen or ten-twelve, those kind of diets.

    3. RC

      Yeah. I mean, there's no question your work and your research has hugely influenced the way that I practice medicine and what I do with my patients. And, you know, I think a really good place to start this conversation would be to really help us all understand what happens in our body when we have a period of time when we're not eating.

    4. SP

      Yeah. So my, uh, research background is, uh, circadian rhythm or twenty-four hours rhythms, which means that our body is actually designed to be at its peak performance, whether it's metabolic, physical, biochemical, or, uh, intellectual performance, peak performance at every hour of the twenty-four hours day. And we all evolved on this planet with, uh, twenty-four hours light-dark cycle and eating-fasting cycle, so that's why we are designed to go through this at least twelve to fourteen hours of fasting every day. So now coming back to what happens during this period of time, one thing is this fasting has to be consistent from one day to another, consistently at the same time, so that our body's internal program recognizes that fasting is going to occur, so there is a lot of preparation, init- internal preparation. The circadian rhythm does that preparation. So after your last bite of the dinner, for example, if it happens at six o'clock in the evening, then although your mouth finished chewing the food and swallowing, that food is going to be digested for the next five hours. So the first five hours of your overnight fasting, uh, your body is actually not fasting. It's digesting the food. And then after five hours, uh, approximately five hours, the food goes to intestine, and then nutrient absorption happens for the next few hours. And during this time, the body is using most of the glucose and stored glycogen for fueling our system. And then slowly, when it runs, uh, low, uh, on glycogen, so which happens maybe seven, eight hours or even ten hours, um, after our last meal, then it slowly begins to burn a little bit of fat. And when the fasting period aligns with your sleep, then there is another magic that happens. That is, um, our gut lining and many parts of our body actually gets a lot of damage throughout the day, and they have to be repaired, and that repair process happens only when we are in our deep sleep and also we are fasting. Uh, we don't have too much food to digest. So after nine to ten hours, this is when, if you're asleep, then, um, your pituitary gland will produce growth hormone that will travel to many parts of your body, including the gut lining, and, uh, to trigger the repair process. So that's when a lot of the repair process will happen. Your, uh, gut lining will get repaired. Many other tissues will get repaired. And then after maybe twelve hours, twelve to fourteen hours, that's when, uh, our body will produce enough... will break down enough fatty acids or stored fat to produce a little bit of ketone. And this ketone, um, now begins to fuel your body. And then ketone is also, v- uh, very recent discoveries suggest that ketones are anti-inflammatory because they affect the immune system. The immune cells also like ketone in many different ways. Um, one is they can use it as fuel.

    5. RC

      Mm-hmm.

    6. SP

      Ketone is a fuel. And second is ketones are also signaling molecules, so that means they can instruct the cell to do... to turn on different kind of programs. So one of the programs they turn on is anti-inflammatory program.

    7. RC

      Yeah.

    8. SP

      What we are also learning is this is just the tip of the iceberg because until now, no one has actually done a very systematic experiment, uh, even in laboratory mice, to see what happens during this fourteen to sixteen hours of fast in different organs. As we all know, we have at least a couple of dozen different organs, and then our brain, different parts of the brain, is also very different. So, uh, only recently we started doing that, and what we are finding is, uh, it's amazing. Like, when we go through this fasting, uh, if we compare this... So let me dial back and tell you what experiment we did. [laughs] We, we took the same mice, um, uh, they were the same genotype. They are born to the same mom with the same microbiome. One group of mice got to eat whenever they wanted. The other group of mice were given food eight to nine hours every, uh, night because mice are nocturnal. And then after few weeks, we took out, um, 20-plus different organs and brain regions from these mice in every two hours, over 24 hours, to see what is actually going on during this fasting process. And then we looked at all the genes in the genome, so that's 22,000 genes, in each of these 20-plus organs at every time point, in male and female mice. Uh, so it's a huge experiment, and this is something that has never been done, even in, uh, caloric restriction and other types of nutrient intervention. So the number one thing that we found is by imposing a strong feeding-fasting cycle, we could see that nearly 80-plus percent of the genes were changing what time they were turned on or off, or how high or low they were going up or down.

    9. RC

      Wow.

    10. SP

      So that means really by changing your eating time, you can be the master conductor of your own whole genetic program. And that is amazing because, uh, in many previous studies, people just look at one organs, the liver or the gut or, uh, fat tissues or muscle, and they find few hundred genes changing. But when you cast a wider net... So that means it impacts almost every organ in our body.

  2. 7:27 – 13:11

    Timing as a Master Lever: Better Sleep, Fewer Calories, Better Food Choices

    1. RC

      This is huge. As a medical doctor, I'm always looking for a few things with my patients. First of all, I'm looking for what is the root cause of why this person's come in? Not necessarily the symptom. The symptom-

    2. SP

      Mm-hmm

    3. RC

      ... is important to me.

    4. SP

      Yeah.

    5. RC

      But it's more important for me to understand what's driving this in the first place? And I'm always looking to see how can I help my patient go further and further upstream? What's one change I can help them make that will have multiple downstream benefits? And what I hear with this new research that you guys are doing is the timing of your food intake, as you say, can be this master conductor. It can have multiple effects on genes, inflammation, immune system function, all kinds of things. And, and, and one other thing that's always fascinated me about your work is the whole, the whole conversation around nutrition for many years, and even now, is still dominated by what we should be eating. You know, should it be fat, carbs, protein? What proportion? And I'm not saying those things are not important, but your research beautifully demonstrates that timing of food intake is something we also need to pay a lot of attention to.

    6. SP

      Yeah, so it's very intuitive, and it's very simple to follow as well. So for example, I don't know about you, but I cannot remember how many calories I ate yesterday, and what fraction of that calorie was, uh, simple versus complex carb, uh, how much was protein, fat, or carb. So for implementing in day-to-day life, although these are very important quality and quantity of nutrition, the timing becomes very easy because we all know what time it is. Uh, we, we schedule our whole day around time. Another thing that we are finding is when people control the timing of their food, then as I mentioned from our surprising discovery with, uh, gene expression data, uh, they also s- seem to sleep well. And once their sleep improves, then the repair process improves. And once, uh, somebody sleeps well, then the food craving and, and craving for energy-dense diet, that also goes down. So that means, uh, by controlling timing, we can inadvertently change the nutrition quality and quantity, and that's now seen in many clinical trials with time-restricted eating or intermittent fasting. People, although they are asked to eat within eight, nine, or 10 hours window and then leave the rest as fasting, um, when you go back to analyzing what they ate, um, then what we find is they modestly reduce their calorie intake by somewhere between 5 to 10, and in some cases, some people can reduce even by 20%, um, which is pretty good because, um, intentional calorie restriction is very hard. For people to reduce calorie by even 10 to 20% every single day is very hard. Second thing-

    7. RC

      So you're, so you're seeing the side effects-

    8. SP

      The side ef-

    9. RC

      ... of people focusing on a particular eating window, whether it be eight hours or 10 hours or 12 hours, whatever it might be-

    10. SP

      Yeah

    11. RC

      ... you're seeing side effects that actually people are also consuming less calories without actively trying to reduce their calories.

    12. SP

      Yeah, 'cause, um, previously we thought some nutritionists, um, had imagined that when people are going through long period of fasting, they might gorge and eat more.

    13. RC

      Hmm.

    14. SP

      Um, but, uh, we, we find exactly the opposite. People reduce their calorie. Second thing is since they're s- sleeping well, then they also improve their nutrition choice. Um, so in almost every study, we find pe- people reduce their alcohol intake. Of course, there is less opportunity to drink alcohol. Um, and then they also reduce processed food, and we don't know why, but it may be because they're sleeping well, because a sleep-deprived brain actually looks for highly processed food, nutrient-dense diet. And when people sleep well, then they can take that decision. Um-

    15. RC

      I think everyone intuitively knows that.

    16. SP

      Yeah.

    17. RC

      Even if they don't understand the science-

    18. SP

      Yeah

    19. RC

      ... I think everyone knows that experience when they haven't slept well. You know? Yes, you can talk to the science of leptin and ghrelin and-

    20. SP

      Yeah

    21. RC

      ... the hunger hormone goes through the roof, and your satiety hormone goes down. But actually, I think we all know when we haven't slept well, we're, we're, we want more caffeine

    22. SP

      Yeah

    23. RC

      ... we, we crave more food. You know, this happened to me a few days ago. We're hungry all the time, and you're not craving-

    24. SP

      Yeah

    25. RC

      ... healthy whole foods at that time.

    26. SP

      Yeah. Yeah, yeah.

    27. RC

      You're craving sugar, high dense, you know, high energy dense foods.

    28. SP

      Yeah, because your brain actually gets confused how long it'll stay awake, and since brain consumes a huge amount of, um, energy, uh, per unit mass, um, that's why it kind of programs you to eat more because it doesn't know how long it'll stay awake. Um, so that's one side effect that we see. So by, by tuning your timing and eating within eight to 10 hours, you can also reduce calorie and improve nutrition quality. And, um, so that way, although quality and quantity of nutritions are very important, um, by focusing on timing, one can improve those two aspects to them.

  3. 13:11 – 21:09

    The First Hour After Waking: Hormones, Coffee and Tea

    1. RC

      So let's go into timing.

    2. SP

      Yeah.

    3. RC

      Okay? Lots of things happen in the body when we have a period of time without foods, ketone production, uh, reduction in inflammation, change in genetic expression, ability to repair and rejuvenate better. But I guess there's an ideal body clock that if the modern world didn't drive us to do certain things at certain times, that we could all beautifully follow, and then there's real life for many people.

    4. SP

      Yeah.

    5. RC

      So let's start off by going, what does an ideal body clock look like for someone? Let's say they wake up.

    6. SP

      Mm-hmm.

    7. RC

      Um, I know you're a big fan of saying that we should try not to eat for the first hour after waking up. Is that true, and if so, why is that?

    8. SP

      Um, so most of us when we wake up, we, we're waking up to an alarm clock, or, um, we have to go to office or do something or take care of the children, so that's why we're waking up in the morning. So that means our sleep hormones are still high. Although we just dragged ourselves out of the bed, our hormones, uh, particularly melatonin, is still pretty high.

    9. RC

      Mm.

    10. SP

      And that takes an hour or two to go down, and within 45 minutes of waking up, our stress hormone cortisol reaches its peak. Uh, so th- this is the time when you can say changing of the guards that happens in the morning. [laughs] So the sleep hormones are coming down, the stress hormones are going up, and your body is actually not ready to digest food and assimilate nutrient, uh, perfectly because, uh, melatonin inhibits glucose-induced insulin, uh, release from the pancreas. So that means within an hour of waking up, um, most of us still have pretty high level of melatonin, which can inhibit this insulin release. Uh, so if we eat something, um, or drink tea with, uh, milk and sugar, to process that, our body has to produce and release sufficient amount of insulin, which may not happen properly in the first one hour.

    11. RC

      So in the first hour-

    12. SP

      Yeah

    13. RC

      ... I love this changing of the guard analogy, particularly as you're in London at the moment.

    14. SP

      Yeah. [laughs]

    15. RC

      Um, so I think that's a very practical tip that everyone, no matter what diet they choose to follow, no matter what culture they're from, no matter what country-

    16. SP

      Yeah

    17. RC

      ... they live in, that seems like quite a good universal principle for all of us. Whenever you wake up, for the first hour, don't eat any food. But you're also saying no coffee or tea with milk and/or sugar. So does that mean, according to this model, a black coffee or a black tea is okay at that time, or would you still advise that gets pushed a bit forward as well?

    18. SP

      Uh, well, uh, many people ask me why can't they have one small teaspoon of sugar or a little bit of, uh, milk. So for an average size person like me, if you drain all of my blood, um, you'll get around five liters of blood. And since the glucose concentration in my blood should be below 100 milligram per deciliters, that means, um, you'll get maximum five gram of sugar from my blood. So that means even if I drink a tea or coffee with half a teaspoon of sugar, so that's 2.2 grams of sugar, if that's not processed properly, then my blood sugar level will shoot up to 140 or 160, around that.

    19. RC

      Wow.

    20. SP

      So that's why-

    21. RC

      Yeah

    22. SP

      ... even, uh, even... [laughs]

    23. RC

      And, and you're saying at that time, you're-

    24. SP

      Yeah

    25. RC

      ... not going to be able to, or you're unlikely to be able to process it properly-

    26. SP

      Properly

    27. RC

      ... because you've still got these sleep hormones-

    28. SP

      Yeah

    29. RC

      ... things like melatonin, and the stress hormone cortisol are kicking around the system still-

    30. SP

      Yeah

  4. 21:09 – 27:16

    Morning Light, Movement and the Body Clock vs. Brain Clock

    1. SP

      Yeah, so another, uh, thing is light because our body clock is entrained or synchronized by food, but our brain clock is actually synchronized by light. And light is also ... Light also reduces sleepiness. We all know that because it's very hard to s- fall asleep-

    2. RC

      Mm

    3. SP

      ... in a, uh, lighted room. And in the morning if you want to wake up your children, then just open your [laughs] windows and-

    4. RC

      That's true

    5. SP

      ... [laughs] they're more likely to wake up. And this is very important because m- many of us, most of us actually don't get enough light in the morning to synchronize our brain circadian clock and to reduce sleepiness and depression. So light is a strong antidepressant, um, and it has been documented in many, many studies. So if you have the chance to go outside to the balcony or even open all the windows in your room, you'll get good amount of light. And when I say a good amount of light, you need around 1,000 lux of light, uh, for 30 minutes to an hour to synchronize your clock and to reduce, uh, sleepiness and depression. Um, even on a cloudy day in England, you get 5,000 to 10,000 lux of light outdoor. And if you're sitting right next to the window sipping your coffee or tea or drinking your, uh, or eating your breakfast or reading your newspaper, then you're getting around 800 to 1,000 lux of light. So that's one thing that you can do during this, uh, one-hour time. Or, um, if you have to get ready, if you're in the, in the bathroom and if you have a, um, dimmable bathroom light, crank it up, and-

    6. RC

      Crank it up

    7. SP

      ... and you'll ... and if you have those, uh, modern bathroom mirrors that have the light integrated, then that's actually pretty good because light falls straight into your eye and you can crank it up to 800 to 1,000 lux at full, um, strength, and, and that's a good way to get the morning light.

    8. RC

      What about movement at this time? How does that fit into our body's natural clocks?

    9. SP

      Yeah. So exercise is always good. Um, I mean, most of the time. You, you don't have to exercise in the middle of the night, but any exercise is better than no exercise. So you can combine, um, exercise with light exposure by going for a light walk or, um, morning run outdoor, or if you're going to a gym, also s- choose a place that gets a lot of light so you can combine both light and exercise. Exercise and circadian clock, um, they reciprocal interact with each other so that means exercise has some impact. Not as much impact as food or light, um, but the clock has a lot of impact on when is the, uh, perfect time for you to exercise. And we'll get to that, uh, as we move towards afternoon. [laughs]

    10. RC

      Yeah. Okay, so what I like about that initial morning recommendation-

    11. SP

      Yeah

    12. RC

      ... is that you can actually hit all three bases-

    13. SP

      Yeah

    14. RC

      ... in one go if you are able to go for a walk-

    15. SP

      Yeah

    16. RC

      ... in the morning. Then, and you don't take a drink with you [laughs] Right? Then, a- and you don't take a snack with you, then number one, you're pr- you're, you're not going to be eating-

    17. SP

      Yeah

    18. RC

      ... or drinking.

    19. SP

      Yeah.

    20. RC

      You're gonna be getting exposure to natural light, and you're gonna be moving your body.

    21. SP

      Yeah.

    22. RC

      So that's a really powerful thing that we can do. One thing-

    23. SP

      Yeah

    24. RC

      ... that has multiple benefits-

    25. SP

      Yeah

    26. RC

      ... on our physiology and on our circadian clock. Before we move beyond that, you mentioned something that I found fascinating. Food helps us reset our body clock. Light helps reset our brain's clock. C- can you explain what, what, what is the difference between, uh, our body clock and our brain clock?

    27. SP

      Yeah. So, uh, almost every cell in our body, in every organ has its own clock. Um, and when we say clock, um, one thing that comes to our brain, comes to our mind is sleep because-

    28. RC

      Mm-hmm

    29. SP

      ... um, we go to sleep every night and then wake up, and if we think what happens during sleeps, uh, during sleep many things happen to our brain and, uh, three, uh, that can be summarized into three things. One is repair, reset, and rejuvenation. Our brain repairs itself. We know that the brain takes out its-

    30. RC

      Mm

  5. 27:16 – 36:26

    Midnight Snacking, Food Hangover and Social Jet Lag

    1. RC

      so I'll tell you what happened a few nights ago. So, uh, it's Thursday morning as we record this.

    2. SP

      Yeah.

    3. RC

      Now, normally for me, I, I, I have a consistent lifestyle-

    4. SP

      Yeah

    5. RC

      ... and usually my rhythm is that I will go to bed at 9:00 PM, maybe sometimes before, but roughly I'll be, you know, in the bedroom from 9:00 PM, a bit before, or asleep then-

    6. SP

      Mm-hmm

    7. RC

      ... and I'll wake up around 5:00. That is, I'm at my best when I do that, and have sort of rhythms around my life and my work that help me stick to that. Now, on Tuesday night, I came down to London, and I was doing my very first live podcast event on stage in the evening. So the event started at 8:00 PM. You know, this is with lights on me, uh-

    8. SP

      Yeah

    9. RC

      ... and my guest on stage. By the time I left the venue, uh, it was probably about 11:15 PM, and I had eaten early, but I got back to my hotel room, I was, I was still wired-

    10. SP

      Yeah

    11. RC

      ... it- mentally. Uh, really had a wonderful evening, and I had some, you know, healthy kind of food in my hotel room. I had some cashew nuts. I think I had some, uh, dried mango slice as well, which we can argue whether that's healthy-

    12. SP

      Yeah, yeah

    13. RC

      ... or not. And even though I know your research, even though I've written books referencing your research-

    14. SP

      [laughs]

    15. RC

      ... I'm a human being, and I thought, "Oh, I'll just have a little bit," so I was just unwinding with that.

    16. SP

      Yeah.

    17. RC

      So I was probably eating at around midnight, right?

    18. SP

      Yeah.

    19. RC

      I still woke up the next day at 5:00, even though I didn't want to. I didn't have to be up, but-

    20. SP

      Yeah

    21. RC

      ... it's like clockwork in my-

    22. SP

      Yeah

    23. RC

      ... body. I, I wake up at 5:00. No alarm clock.

    24. SP

      Yeah.

    25. RC

      I felt exhausted the following day, all day.

    26. SP

      Yeah.

    27. RC

      Obviously, I had less sleep.

    28. SP

      Yeah.

    29. RC

      I was hungry all the time, at times when I wouldn't normally be hungry, and so I really struggled on Wednesday. This was yesterday.

    30. SP

      Yeah.

  6. 36:26 – 48:10

    Finding the Right Eating Window: The 13-Hour Math and Why 10 Hours

    1. RC

      You published your first seminal paper almost 10 years ago to the date, which basically sparked off this phenomena around the world, which has gone into multiple different directions of intermittent fasting.

    2. SP

      Yeah.

    3. RC

      In the last 10 years, from all the research you've done, from all the research you've seen being done around the world, uh, with the understanding that everyone's unique and everyone's different, do you think you have a universal recommendation-

    4. SP

      [laughs]

    5. RC

      ... like a, this kind of eating window is gonna work for most people? Do you know, what, would you have a number that you would recommend?

    6. SP

      Yes, that's a little tough, um-

    7. RC

      It is a tough one, yeah

    8. SP

      ... so let, let's start from, uh, means we started the conversation from the morning-

    9. RC

      Okay

    10. SP

      ... and we said, uh, one hour we should not eat, and then, um, when should we eat? Um, so the breakfast or the first meal, uh, that breaks your fast, because let's redefine breakfast. Breakfast is actually the first meal that breaks your fast.

    11. RC

      Okay.

    12. SP

      Not the morning, not necessarily the morning meal that you have to eat. Um, so, uh, you have to eat your breakfast at a consistent time because of this, its effect on body clock, because the breakfast time actually is most powerful in resynchronizing all your, all your clocks and then telling, okay, so I'm in the same time zone, uh, let's start the day. And then the question is, should somebody eat within 4 hours, 6 hours, 8 hours, 10 hours or 12 hours or more? Um, so we can do some simple math and then we'll reach what would be the ideal one.

    13. RC

      Okay.

    14. SP

      Okay. So we know that after we eat, after, after we finish our dinner for the first, for the next 5 hours, it's not actually fasting, it's digesting our food in the stomach. So that means, um, we should have those 5 hours, uh, set aside. And then, um, we should actually sleep for, uh, we should be in bed for 8 hours. So even if you... Suppose say you finish your dinner at 6:00 PM, you're not going to sleep right away because your s- stomach is digesting food, your core body temperature is high because blood is flowing to the, to the stomach to absorb that nutrient. So you need two to three hours, um, after your l- dinner to get ready for your sleep. So now, uh, we'll take two to three hours after your last meal and then add eight hours of being in bed. So eight hours plus two hours, so that's 10 hours. So now in the morning you've got to wait for an hour, so that's 11 hours. So that leaves 13 hours window within which one can choose to eat for X number of hours. So nobody should eat for more than 13 hours, uh, necessarily, uh, according to this math. So now if we come back to clinical studies, um, there are some studies where people were asked to eat everything within 12 hours every single day, um, but unfortunately we didn't see much benefit. So 12 hours, um, every single day is not a good idea. Then if we look at-

    15. RC

      When you say not a good idea, let's say, and I know your app-

    16. SP

      Mm-hmm

    17. RC

      ... has shown that a lot of people are eating over 15 hours.

    18. SP

      15 hours.

    19. RC

      Right?

    20. SP

      Yeah.

    21. RC

      And a lot of people don't realize they're doing that.

    22. SP

      Yeah.

    23. RC

      Right? Because that includes, of course, sugar in their coffee or a little snack in front of the TV at night. So if you are currently consuming over 15 hours or 14 hours-

    24. SP

      Yeah

    25. RC

      ... right?

    26. SP

      Yeah.

    27. RC

      Moving to only doing it over 12 hours presumably is a good thing?

    28. SP

      So it's a good thing to some extent, but what happens is people who are, um... Yes, somebody is... If someone is eating over 16 hours and now moves to 12 hours, that person will get some benefit because that four hours delta, the change in re- reducing eating window by four hours, uh, will benefit that person.

    29. RC

      Okay.

    30. SP

      Um, and, uh, many different types of benefits may im- improve nutrition quality and then we don't know whether it'll help to reduce calorie intake, uh, significantly to the point that the person will see some benefit.

  7. 48:10 – 58:45

    Evolution, Evening Hunger and Eating Earlier in the Day

    1. RC

      Yeah, a couple of things there for me. Um, I agree some people really struggle initially.

    2. SP

      Yeah.

    3. RC

      Um, but actually some people also find it quite liberating I found. There is a subsection of my patients who in the past I found that they find like an eight-hour window where they're eating very liberating, and once they get used to it-

    4. SP

      Yeah

    5. RC

      ... they actually find that they've got more energy, less hunger. It speaks to this idea that we can maybe train our circadian biology to a certain degree by having a consistent pattern.

    6. SP

      Yeah.

    7. RC

      And, you know, as we have this conversation, I've been in clinical practice for over 20 years, right? And I've learned that very few things apply for every single person.

    8. SP

      [laughs]

    9. RC

      And you have to take into account a person's lifestyle, their previous history, their job, what their family are doing, all these kind of things. And so I have these recommendations, but I'm loosely attached to them 'cause I realize that people have to be able to, to personalize them. You know, you've done a lot of science on this, right? Which is clearly- In the times in which we live, a lot of people need that science to persuade them that this is something that I should be doing. But if we just zoom out for a minute-

    10. SP

      Mm-hmm

    11. RC

      ... and look back at our evolutionary history as humans, actually, it's hard to make the case that we would've been eating consistently over 13, 14, 15 hours in every 24 hours. You know, we would've naturally had these long periods where we didn't eat in every 24 hours. So yes, there's science to support it, but there's also, if we look at our lives through an evolutionary lens, it kind of works as well, doesn't it?

    12. SP

      Yeah, it does. And in fact, uh, yeah, our ancestors, hunter-gatherers or farmers, um, they didn't have access to plenty of food. And another thing was, um, they didn't have access to processed food, so food was not ready for consumption any time of the day. So in the morning, um, people typically spend time gathering food or preparing for cooking and, um, the first substantial meal, uh, was maybe around lunchtime.

    13. RC

      Mm-hmm.

    14. SP

      Um, and then in the evening after everybody came back home, um, that evening time was very important, and it's still important. And if we think about human history, um, what we do in the first six hours of the evening [laughs] after we get home, that actually determines every aspect of our life. Because after we come home, our hunter-gatherer ancestors or farmers, they lighted a fire, and they cooked or grilled food or whatever they had gathered, and then they shared that food, so there was social aspect of eating. And then that's the time when people feel liberated from their daily life. So you have come home, the- you are not working for a boss, and that freedom time, two to three hours after dinner, is very important for a lot of people. And our ancestors, hunter-gatherers, that's the time when, uh, life changed. Uh, so daytime people thought about how to work to bring food to the table, and after dinner they became more creative. That's when people started, um, singing, dancing, talking about philosophy and science and politics. Um, so that's the... Our cradle of civilization is actually in that evening time. So we should not forget that, so we have to keep in mind that, uh, people have to come back and, um, in their lifestyle, they have to socialize and, and do certain things, and, uh, that dinner time is very important. Uh, so going back to your question, uh, that people have to relate not only to science, but also to society and culture and how we have evolved on this planet. They can keep that in context, and maybe delay the breakfast in the morning because that's what our ancestors did, and, uh, that also aligns with our physiology because when people are in experiments, when people are isolated inside laboratory without any cue what time of the day or night it is, what we have found is our hunger, subjective hunger actually reaches its peak in the evening, not in the morning. And that makes sense because a lot of people actually will say that they don't feel that hungry in the morning. But almost everybody would say that they have some hunger in late afternoon or evening. So we are programmed to be hungry towards the end of the day, and that hunger, since it's universal, everybody feels that. That's also is a basis for that socializing and, um, consuming food in a gathering, and then discussing something other than how to [laughs] how to make money to bring food to the table.

    15. RC

      How, how does this fit with... There's quite a lot of research that I've read which is showing that if we consume the bulk of our calories in the first half of our day compared to the second half of the day, that can have powerful effects on our circadian clock, on weight, on sleep, on immune function, all kinds of things.

    16. SP

      Yeah.

    17. RC

      And so, you know, there's obviously a phrase, is it there, "Breakfast like a king-

    18. SP

      Yeah

    19. RC

      ... lunch like a prince, dinner like a pauper," which I think works really well for a lot of people actually.

    20. SP

      Yeah, yeah.

    21. RC

      But how does that fit in with what you've just said, which is that we are wired to maybe feel hungry later on in the day, maybe late afternoon, early evening? Because on the face of it, it might seem as though these things are quite opposing.

    22. SP

      Yeah. So when I say that, it's not that we are saying that people should just consume food in the evening.

    23. RC

      Okay.

    24. SP

      Uh, they'll still... [laughs] Uh, it's true that in the first half of the day, uh, our blood sugar control is much better. And, um, as physician, you might have seen that if you do a oral glucose tolerance test, which is looking at blood glucose, uh, X number of hours after, um, a bolus of sugary drink, then, um, the same person may s- may look normal in the morning when the glucose tolerance test is done, but in the evening that person's glucose will shoot up. Uh, or late night it'll shoot up, and you may diagnose that person as diabetic. Uh, so there is this aspect of our glucose regulation, particularly insulin-producing cells have their own clock so that, um, blood glucose level-

    25. RC

      Mm

    26. SP

      ... uh, shoots up in the evening. So that brings up what we should eat at different time of the day. And the analogy that I give, uh, again, another thing is our hunter-gatherers, uh, when they were lighting of the fire, they're not lighting a fire to actually eat berries. They're lighting a fire to eat meat- Or-

    27. RC

      That they-

    28. SP

      ... complex carb that needed a little bit of, uh, cooking so that that-

    29. RC

      Yeah

    30. SP

      ... would become palatable. They were not actually lighting fire to, um, warm up their chips and ice cream to eat. [laughs]

  8. 58:45 – 1:08:30

    Benefits of a 10-Hour Window, Medication Cautions and Athletic Performance

    1. RC

      Can you summarize? If most people, if anyone listening to this or watching this goes, "Okay, I'm going to now try and, uh, eat all of my foods that I'm gonna consume, whatever diet that might be-

    2. SP

      Yeah, yeah

    3. RC

      ... within a 10-hour eating window." So first thing I want to clarify ... Well, within a 10-hour eating window, can you list what are some of the benefits they may get?

    4. SP

      Yeah, so, well, once people eat within 10-hour eating window, um, what we find is, uh, within few days, um, that may be two to three weeks, they may find their sleep will improve, and this is something that we find in many of our patients, uh, who self-report how is their sleep. Um, it may not increase the number of hours they sleep, but it may just improve their sleep satisfaction. They might actually get into a better sleep.

    5. RC

      Mm-hmm.

    6. SP

      Quality of sleep will improve. Um, then those who have acid reflux, I don't know the numbers in the US, in the UK, but in the US, um, there are 65 million prescription for acid reflux-

    7. RC

      [laughs]

    8. SP

      ... every year.

    9. RC

      Yeah.

    10. SP

      And there is lot of over-the-counter acid reflux medication. So that means almost more than half of the adult population experiences some kind of acid reflux or s- stomach issues every week. Uh, so we also hear that, um, people have much better, um, gut health, uh, within two to four weeks, um, they will feel that. Um, so sleeping better and then having better gut health will also improve the sense of energy in the morning and throughout the day. So these are the ... We think that these three benefits are the positive feedback loop that helps people to sustain with 8 hours or 10 hours-

    11. RC

      Yeah

    12. SP

      ... eating window. Then those who have prediabetes or Type 2 diabetes, um, with, um, minimal medication, for example, metformin, um, they may also find that blood sugar control will improve, particularly the nighttime or the, the time period in which they are fasting. Um, at least in that period, 14 hours or 16 hours, um, the blood sugar will remain, uh, much better under control. Then, uh, surprisingly, many studies, although we haven't connected how it works, we find that people with hypertension, uh, they improve both their systolic blood pressure and diastolic blood pressure, and that can happen between six to eight weeks after trying this, um, regimen. So- The flip side is if, uh, people are already on hypertensive drugs, then after four to six weeks, they should actually check their blood pressure to make sure-

    13. RC

      Yeah

    14. SP

      ... that they should do some mid, uh, dosage adjustment.

    15. RC

      I, I think this is just-- I think we should pause there because I think this is an important point. There are all these incredible benefits on the other side of this.

    16. SP

      Yeah.

    17. RC

      And so one of my cautions with patients, and, and again, I'd caution anyone listening or watching, if you have type 2 diabetes or if you are on any blood sugar-lowering medication from your doctor-

    18. SP

      Yeah

    19. RC

      ... you might wanna just have a chat first because-

    20. SP

      Yes

    21. RC

      ... because your blood sugar starts to come down, you may not need that. So what I've always done is I would stop, like, something like glipizide, for example-

    22. SP

      Yeah

    23. RC

      ... which can drop blood sugar.

    24. SP

      Yeah.

    25. RC

      I would usually stop that-

    26. SP

      Yeah

    27. RC

      ... when we're transitioning over and then revisit this in a few weeks to see, you know, or a few months, you know, what do we need now? Metformin usually is okay, I've found.

    28. SP

      Yeah, metformin is okay.

    29. RC

      Um, but blood pressure medicines-

    30. SP

      Yeah

  9. 1:08:30 – 1:15:26

    Teenagers, School Start Times and Circadian Chaos

    1. RC

      the other thing I wanted to comment on is my son's 11, and one thing me and him do most Saturday mornings, if not every Saturday mornings, is go to the local park run, which is a 5K run-

    2. SP

      Yeah, yeah, yeah

    3. RC

      ... around the local park, right? Which, you know, these park runs are transforming communities and people's-

    4. SP

      Yeah

    5. RC

      ... people's lives in so many ways. And what I'm trying to do with my kids is help them start to pay attention to what happens when they do certain things. For example, "Oh, I feel tired and sluggish, I don't wanna go." "Oh, now that we've gone, how do you feel now?" Rather than, you know, Daddy telling him-

    6. SP

      Yeah

    7. RC

      ... it's like, "Oh, yeah, I've got more energy now. Even though I didn't wanna come-

    8. SP

      Yeah, yeah

    9. RC

      ... I've got more energy." And now I've also asked him, we used to say, "Just pay attention now to what time we eat the night before, and how you're doing, and how your time is on a Saturday morning."

    10. SP

      Yeah, yeah.

    11. RC

      And I think he's already started to draw the comparison. And when we stick to the early meals on a Friday evening, my sleep's better and I'm running better on a Saturday-

    12. SP

      Yeah, yeah

    13. RC

      ... compared to... Do you know what I mean?

    14. SP

      Yeah.

    15. RC

      So I'm, I'm taking your science and I'm trying to actually, instead of teach it to my son, I'm trying to just help him start to pay attention to, "Oh..." Do you know what I mean?

    16. SP

      No, actually, this is, uh, you're doing the right thing because, um, this is a time, particularly teenage time, that's when the, the kids, uh, after they, after they get into late middle school and high school, um, this is when all of our circadian disruption happens.

    17. RC

      Right.

    18. SP

      Um, because that's when they get a lot of homework, they have to stay up late into the night. And when they stay up late into the night, they think, and often they're also told, that your brain cannot function unless you have a late-night snack. And [laughs] they get used to that late-night snack and staying up late in the night, and in the morning they are sleep-deprived, and, uh, they have to rush to the school. And I don't know what is the school start time here, but in the US, for example, um, most of the school start time used to be 7:30 in the morning before the pandemic started. So, um, in collaboration with Horacio de la Iglesia, who's a professor at, um, in Seattle, um, he did a very simple study. Uh, what he did was he was looking at sleep, and we know that many teenagers, starting from middle school to high school and college, they're sleep-deprived. And, uh, that's also the time when their, their circadian clock tells them to wake up a little later than, um, adults and also, uh, toddlers. So, um, the experiment was to delay the school start time by an hour, um, and to track the students be, uh, before and after, uh, the school start time was delayed. So we tracked nearly 200 students in two different schools, um, their sleep habit, their activity, and their academic performance. And when school start time was delayed by an hour, these kids got 35 minutes, um, more sleep, extra sleep. And when they got that 35 minutes extra sleep, then many parents would think that now kids are sleeping more, so they're not doing their homework, and their [laughs] , that-

    19. RC

      Yeah

    20. SP

      ... 35 minutes is coming from their homework time, so their grades might go down. But actually, what we found was their grades improved by 4%. And a 4% grade improvement is, is, can be pretty big for people who are struggling. Uh, those who are getting B grade, they can go to A grade. So this is an example where small change, uh, starting from middle school or high school, can have a huge impact, not only on their health, but also on their academic performance. And if we go back to now, actually in the pandemic, uh, quite a few things happened. One was, uh, the kids were, uh, at least in the US, many kids were always on Zoom-

    21. RC

      Yeah

    22. SP

      ... and they lost track of that regularity in their life. Uh, they didn't have access to a lot of bright light. Uh, there was social isolation. And, um, and they were also watching a lot of TV and eating late into the night. Um, so now, uh, this has become... And also, since there was online education a lot, the time at which people had to resubmit their homework also, uh, inadvertently now has become midnight. So in high school and colleges, at least in the US, the deadline for submitting your homework is midnight. So that means th- it's now institutionalized that students should stay awake until midnight to finish their homework and submit it. And this is, um, so-

    23. RC

      So this is circadian chaos.

    24. SP

      This is circadian chaos, which is now institutionalized, um, uh, at least in the US, uh-

    25. RC

      Well-

    26. SP

      ... for all high school and, and colleges.

    27. RC

      So this is something that, I've got to be honest, I find incredibly frustrating, um, particularly with schools, but it applies to adults as well Which is also what happened over the last two or three years, is that schools that weren't really using technology that much with their kids, now everyone's-

    28. SP

      Yeah

    29. RC

      ... on technology. And even though a lot of schools now, well, in the UK are completely back to normal, the screens have stayed.

    30. SP

      Yeah.

  10. 1:15:26 – 1:28:09

    Evening Light, Screens and the Discovery of Melanopsin

    1. RC

      What's going on with light in the evening, and what can we do to kind of mitigate that, both for children but also adults?

    2. SP

      Yeah, so light, uh, is extremely important when it comes to brain clock, and in the morning you got to resynchronize a brain clock to day and night cycle, and it reduces depression, brings alertness. And, uh, for the last 200,000 years, um, humans never saw too much bright light after sunset. Um, the light, uh, the fire light or the candlelight, um, is very dim, and it also doesn't have too much blue light.

    3. RC

      Yeah.

    4. SP

      So we are designed to see only dim light or orange color light in the evening. And even if you go back to the history of light in the UK in 1850, between 1850 and, uh, 1900, um, the cost for lighting of an average size UK home for two to three hours every evening, uh, was substantially high. Uh, it used to consume almost, uh, a week's worth of income.

    5. RC

      Wow.

    6. SP

      So people actually didn't... Light was expensive. So only in the last several, [laughs] last 50 years or so, uh, the cost of lighting, um, I'm not talking about your entire gas bill and all these bills, just lighting, uh, is less than 1% and actually less than .5% of an average household's income.

    7. RC

      Wow.

    8. SP

      So we have, uh, plenty of light. And in fact, now we all want bright light. So, um, light pollution in our house [laughs] has become a big deal. Second is, uh, the screen time. We are essentially looking at rectangular pieces of glowing objects until, from the time we wake up until we go to fall asleep.

    9. RC

      Yeah.

    10. SP

      And, uh, so, uh-

    11. RC

      What, what a-

    12. SP

      [laughs]

    13. RC

      ... what a time to be alive, eh?

    14. SP

      [laughs]

    15. RC

      Of course, there are many benefits. I'm just, you know, having a joke.

    16. SP

      Yeah, yeah, yeah. And, uh, you know, we are also talking now, we are thinking about metaverse where the light will be actually attached to our head. [laughs]

    17. RC

      [laughs]

    18. SP

      Looking at rectangular pieces is not enough. We have to actually attach it.

    19. RC

      Sorry to interrupt. If you are enjoying this content, there's loads more just like it on my channel, so please do take a moment to press subscribe, hit the notification bell. And now back to the conversation.

    20. SP

      So, uh, this is kind of the silent epidemic, um, that has begun, and I think from circadian point of view, we are at the same point as, uh, what used to be the, what I call the lead and asbestos moment. So this is a time when we realize, when we're beginning to realize what is the widespread health impact or disruption of circadian rhythm disruption by having exposure to too much light, ambient light, and also screen time, and reducing sleep or reducing sleep quality and eating at the wrong time. All of these three are conversing. But just like smoking cessation or lead and asbestos took almost a generation to correct, I guess we are at the very beginning of that correction phase, and it'll take us almost a generation. But at least few things that we can begin to implement in every family, and you're doing pretty good, uh, awesome setting an example for your kids, is to come up with, uh, simple rules that, uh, two to three hours before bedtime, there should not be any bright light exposure. So at home, for example, now is a good time to put almost all, all your lights in dimmer so that you can dim the light, not flip, switch it on or off, and then use indirect light. So that means light that doesn't illuminate your face, but actually the workspace.

    21. RC

      Yeah.

    22. SP

      Um, table lamps, for example, in the old days. Um, so those kind of lights. And also for all of your devices, uh, make sure that your, all your devices are set to the minimum brightness.

    23. RC

      Mm-hmm.

    24. SP

      Because if that is your default, um, setting, then during daytime, of course, most of the devices will crank up the brightness to, uh- Compensate for the ambient light, but at nighttime, at least they will go back to the minimum brightness.

    25. RC

      So you mean that, so go into your computer or your phone-

    26. SP

      Phone

    27. RC

      ... and change the setting so that it automatically starts low?

    28. SP

      Yeah, yeah.

    29. RC

      Or are there settings you're talking about where it, it changes according to the ambient light?

    30. SP

      Yeah, so, uh, most of the devices now will change according to ambient light, but they will always come back to, uh, in the dark, they'll come back to your default setting.

  11. 1:28:09 – 1:39:12

    Shorter Windows, Late Eating and the Mouse Lifespan Study

    1. RC

      Going back to eating windows-

    2. SP

      Yeah

    3. RC

      ... okay, so we've said that 10 hours-

    4. SP

      Yeah

    5. RC

      ... appears to be a pretty good universal recommendation that most people tend to find works around social life, work life, and what they're able to do. Now, there's a huge trend these days in the kind of low carb or, um, keto community to skip breakfast, uh, and maybe go even more aggressive, like eight hours, and maybe, uh, you know, first meal at 12, finish eating by 8:00 PM, or I know some people go even later. They use coffee to get them through in the, in the morning-

    6. SP

      Yeah

    7. RC

      ... and they don't feel hungry at all, so often it'll be 2:00 or 3:00 PM they start, but they'll eat quite late or let's say 10:00 PM. So they've actually got a compressed eating window, but it's towards the end of the day.

    8. SP

      Yeah.

    9. RC

      So I just wanna get into some of the subtleties here. Compared to what most people are doing, which is eating across 15 hours, right?

    10. SP

      Yeah.

    11. RC

      We wanna reduce that.

    12. SP

      Yeah.

    13. RC

      Great. Let's say 12-hour minimum. You're showing a lot of benefits so people can get to 10 hours. Okay, fantastic. Are there increased benefits for some people when they go even lower to, let's say, an eight-hour eating window or a six-hour eating window? I guess that's the first part of the question, and the second part of the question is what do you think about, yes, we have to personalize it to our life, but if we have an eating window that's... M- My understanding of the science is that eating windows that tend to be earlier in the day tend to be more in harmony with our circadian biology, but I have also seen people get benefits-

    14. SP

      Yeah

    15. RC

      ... even though they're doing it late into the evening. So can you maybe put some of that together for us?

    16. SP

      Yeah, so, um, compressing eating window to a narrow interval is almost like exercise. Any exercise at any time of the day is always better than no exercise.

    17. RC

      Okay.

    18. SP

      So similarly, compressing eating window to eight hours if you can do or six hours and, uh, eating healthy nutrition within that eating window is also pretty, uh, very important, and we have to stick to that. 'Cause sometimes what we have seen through our public-facing app, My Circadian Clock, or the research is some people tend to compress that eating window too short, maybe four hours or six hours. At the same time, they, they try to improve their nutrition quality so they're eating only salad or, uh, they reduce their calories, and they may be eating less protein or less, um, fat, and particularly for women, uh, that can... And they're also more active, so that can trigger something what we call relative energy deficit in sports. So many athletes, uh, particularly women athletes, they report this, that, um, most athletes who do triathlon or marathon runners, uh, women, they become amenorrheic. They don't cycle anymore, and they feel that it's so widespread that it's normal, which is not true. So that shows that, um, by reducing calorie or eating within a very short time, and at the same time not paying attention to nutrition quality, can put you into this state where your neuroendocrine system can malfunction. But if you're doing well with nutrition quality, then we haven't seen any study, uh, that compare this very short eating window with a longer eating window. So what we have seen is for people who are obese, diabetic, or pre-diabetic, overweight, if you put them on six hours or four-hour eating window, then they have a lot of adverse event. Um, so for example, they can feel dizzy, they can feel extremely low energy, and sometimes even nausea. Those kind of stuff can happen. But those who are adapting to it, they have to pay attention to nutrition quality. We cannot look at- longevity or overall health comprehensively in humans, but there was a study that just got published couple of weeks ago in Science Magazine. It's not even in full print, it's only in online. Um, and I think that's, that relates to this question. So this is a very simple calorie restriction study in mice. We know that when you reduce calorie in mice by 20 to 40%, then these mi- mice typically live longer than those who eat normal food and within, uh, reasonable, um, nutrition quality. But the question, uh, so... But there is a caveat to all the calorie restriction studies done in mice, that is not clearly mentioned in many of the studies. That is, in calorie restriction studies, usually the mice that are put on calorie restriction, they're given 20 to 40% less calorie, but only one meal, and mice usually finish that meal within three to four hours. And in many cases, they can finish it in, within two hours. So that means they're eating within two hours to two to four hours and fasting for 20 to 22 hours-

    19. RC

      Wow

    20. SP

      ... every single day. Whereas the ad libitum, the control group, has access to healthy nutrition throughout 24 hours. So now the question was whether the life extension effect of caloric restriction is due to calorie restriction or due to long fasting.

    21. RC

      Mm.

    22. SP

      Or, or how do we disentangle these two? Uh, so this is a study that's very well thought out and well planned. It also needed some technological advances where, uh, food can be delivered to mice at any specific time and in specific quantities. So they had the control group that had access to food any time, and then the caloric restriction group was divided into multiple groups. One group got only calorie restriction and no fasting, so that means the reduced calorie food was even s- split into very tiny pellets, and these mice got those tiny pellets in every two hours.

    23. RC

      So through, in a long eating window.

    24. SP

      So, yeah, so in every two hours, they're eating something. They're not actually fasting much.

    25. RC

      Yeah.

    26. SP

      They're just reducing calorie, but no fasting. Um, so compared to the control, this group increased their lifespan by 10%, which is pretty good. I mean, 10% lifespan ext- extension in mice is very good. So now, the same calorie restrict- restricted diet was given within 12 hours. And when it was given within 12 hours, so that means same number of meals, but compressed into 12 hours, so in every thir- every 60 minutes or so, uh, these mice were getting a little bit of food. But they were going through 12 hours of fasting. And all these mice that ate within 12 hours, they got another 10% lifespan extension.

    27. RC

      On top of the other 10%.

    28. SP

      On the top of 10%. So now they're living 20% longer by combining caloric restriction and some time restriction.

    29. RC

      Yeah.

    30. SP

      So now, even they went one step further. They made that 12 hours fasting during daytime, when mice are supposed to fast because mice are nocturnal, or nighttime. So that means these mice were eating during daytime when they're not supposed to eat, and they're fasting during nighttime. So the mice that fasted during nighttime, so that is eating at the wrong time, calorie restriction, so those are the ones that extended lifespan by 20%. But the mice that ate at nighttime and fasted during the daytime, they actually lived 35% longer.

  12. 1:39:12 – 1:48:28

    Mouse Versus Human Evidence and The Circadian Diabetes Code

    1. RC

      What's the relevance to humans? As someone who's literally at the forefront of this research, what do you say to those people?

    2. SP

      No, I guess even in the beginning, when I used to give scientific talks, people used to s- uh, tell me the same thing. Maybe it relates to mice. And in fact, um, for the first few years, I was never funded. Uh, I didn't get any federal funding because the reviewers of my grant, um, made that comment that, um, you know, this may relate to mice, and we know that humans don't eat like mice, so it may not have-

    3. RC

      Mm

    4. SP

      ... any significance. So that actually forced me to go back and ask when people eat, and this was a very simple question that had never been asked objectively. So we made this app My Circadian Clock, and where people had to just take pictures of their food, didn't have to enter what they ate, didn't have to, uh, type in anything. And that was the first generation of that app. And that's when we figured out, we found that nearly 50% of adults in the US, uh, who are not even shift workers, they were eating for 14 hours, 45 minutes. We round it up to 15 hours and say that 50% of adults eat for 15 hours or longer. That's when many human studies started, and the question was, can people who are already eating at 15 or 16 hours change their behavior and try to eat within 10 hours? Because I can come up with a discovery that eating, um, X, Y, Z, for example, maybe avocado with, uh, tomato every single day is good for everybody, but people may not change their behavior. So that was a big question, can people change behavior?

    5. RC

      Mm.

    6. SP

      And what we found was, yes, it was possible. People could change behavior, and there are some positive feedback loops.

    7. RC

      Mm.

    8. SP

      So for example, the gut health, the sense of energy, and sleep. We think those three actually drive people to sustain this behavior. And then there are a lot of, um, small studies, and these are... this is the way translation works.

    9. RC

      Yeah, exactly.

    10. SP

      You go from mice, and then you do a small feasibility study to see whether it's feasible

    11. RC

      In humans

    12. SP

      In humans. And these are u- typically small because you don't want to put too many people at risk by doing something that can even cause harm. Um, so that first phase went through, um, the different types of studies, and also it was gratifying to see studies were done in US, Europe, uh, Asia, Australia. In all these continents, small group, um, male and female, younger and older, people with obesity or diabetes or metabolic syndrome. And universally, in most of the studies, we saw benefit.

    13. RC

      Mm.

    14. SP

      And these studies are also important because they define what benefit we are going to see and what is the magnitude, so that when you design large randomized control study, then you can, um, power them appropriately.

    15. RC

      Yeah

    16. SP

      So now we are going through that phase where the r- large randomized control studies are being done, and also results are coming out. Um, but there is one thing, that we have to keep in mind that in any nutrition intervention study, if you're going to change something, then we should be able to monitor whether people are making that change. And when you're doing small studies, it's easier because, uh, you have handful of people, maybe, uh, 20 or 30 people, and you can monitor when they're eating, and you can also teach them how to comply with the, with the intervention. But when you go to large study, that's the challenge. Can you actually monitor when people are eating?

    17. RC

      Yeah

    18. SP

      And if you cannot monitor, then it becomes very difficult to interpret the results. The second thing is we know that people with obesity, diabetes, and all this metabolic disease, they have adopted a lifestyle or habit that suits them, and they're used to eating over long period of time.

    19. RC

      Mm.

    20. SP

      So they need extra support. They're not the, they're not the b- bleeding as biohackers who are ready to do anything and can take little bit of discomfort and pain. Uh, so you need some, uh, support, education-

    21. RC

      Yeah

    22. SP

      ... and you have to do that in large trial, and that can become difficult. So that's why we have to, we have to keep those in mind now.

    23. RC

      Yeah

    24. SP

      Uh, those eating pattern monitored objectively and whether they were given the right type of support to adapt to this time-restricted eating or intermittent fasting.

    25. RC

      Yeah.

    26. SP

      Yeah.

    27. RC

      Well, one of the things I love in your, um, your latest book, The Circadian Diabetes Code, is there's a, there's a step-by-step plan, and you-

    28. SP

      Yes

    29. RC

      ... go through common problems people have, whether it's headaches or compliance or energy, and how they can deal with that, which I think is really, really helpful. And, you know, although the title of the book is The Circadian Diabetes Code, uh, as I read it, it's like, well, this book will help you whether you have diabetes or not. It's a good recipe for how to live your life.

    30. SP

      Yeah

  13. 1:48:28 – 1:57:17

    Beating Jet Lag and Managing Shift Work

    1. RC

      Just to finish off, uh, Satchin, there's three areas I wonder if we could just briefly touch on, shift work, naps, and jet lag.

    2. SP

      [laughs]

    3. RC

      Um, one of the things that struck me yesterday when I text you, and I know you've only within the last couple of days landed from America, which of course is... You know, you're on the West Coast, so there's an eight-hour time difference between what your body clock is used to and what we're on in the UK. And of course, we've been trying to juggle the time of this conversation, right?

    4. SP

      [laughs]

    5. RC

      And I remember texting you yesterday saying, "Are you sure 8:00 AM's not too early for you? Because I'm aware that-

    6. SP

      Yeah

    7. RC

      ... that's like midnight for your body clock."

    8. SP

      Yeah.

    9. RC

      Um, "Won't you be jet lagged?" And you said something like, "No, I'm not suffering from jet lag." I was like, "Okay, that's interesting"

    10. SP

      [laughs]

    11. RC

      ... because I'm someone who has very much struggled. So why are you not suffering from jet lag, and what are... In your view, what are the key things that we can do to reduce the likelihood that we're gonna be floored by it?

    12. SP

      Yeah, so jet lag is when your brain clock is still thinking you're in the old time zone and your body clock is also thinking in a different time zone. So essentially, your clocks are desynchronized from whatever time zone you are in. And as we have learned that light resets our brain clock and food resets our... the rest of the body clock, then we can use that to reset ourselves to the new time zone. So that means, uh, when I travel US to Europe, most of the flights leave US in the evening or late afternoon and reach Europe in the morning, so that means that should be the usual fasting time for everybody, so no food in flight.

    13. RC

      So you don't eat on the flights?

    14. SP

      Yeah, no food in flight. And if it is short flight, like this was a short flight for me because it was maximum eight hours flying, uh, so that means even I had to finish my dinner or last meal before even boarding the plane. And then in flight, is to not get too much light exposure. So that means the only thing that you should be doing in flight is trying to sleep. So I not only try to sleep, I actually carry a eye mask, a sleeping mask, so that really cut out all the light exposure.

    15. RC

      Mm.

    16. SP

      Um, so no watching television and, um, not even very little or minimal reading, uh, only books or something with, uh, light falling on a book, and trying to sleep. And then after I reached here again, the flight reaches at 6:45 or 7:00 in the morning. By the time you check into the hotel, it's, uh, 8:30 or 9:00. So your breakfast, um, is around 10:00 o'clock in the morning. So I already had a long fasting followed by this very nice big breakfast that reset out my body clock and-

    17. RC

      So food can do that.

    18. SP

      Yeah

    19. RC

      It can just com- it can help literally reset your body clock.

    20. SP

      Reset body clock. And then of course, uh, I had a, a long drive from the airport to the hotel and, um, as I said, even if you're just looking outside, it was a, it was a rainy day in London, but still that much light is enough to keep me awake and reset, so.

    21. RC

      So basically you're paying attention to light and foods-

    22. SP

      Yeah

    23. RC

      ... to help you when you come this way. And I guess when you go back from the UK to the US, the flight will probably be in the daytime-

    24. SP

      Yeah, yeah

    25. RC

      ... the morning or lunchtime from here.

    26. SP

      Yeah.

    27. RC

      Because I've done that many times in the past.

    28. SP

      Yeah. [laughs]

    29. RC

      Uh, not for the last two or three years, having said that, but it's almost the opp- Well, would you eat on the plane this time when you go back?

    30. SP

      Yeah, so this time I'll eat my meal in plane, but then when I land, since I'm landing in the evening, I actually don't need that evening meal, so I can go to the next morning.

  14. 1:57:17 – 2:04:00

    Naps and Panda's Six Final Tips

    1. RC

      just finally then, naps.

    2. SP

      Yeah.

    3. RC

      Um, in looking at circadian biology and how important a robust circadian biology is for, you know-

    4. SP

      Yeah

    5. RC

      ... everything we've spoken about, you know, weights-

    6. SP

      Yeah

    7. RC

      ... type 2 diabetes, inflammation, but also mood-

    8. SP

      Yeah

    9. RC

      ... you know, depression, these sort of things, absolutely really important to have a good circadian rhythm. Uh, in your view, can naps help us if we need them?

    10. SP

      Yeah. Actually, if we go back to human his- the history of humans on this planet, and we are not fully diurnal. We're... What we call, we are crepuscular, so that means we are more active in the morning and evening, and we're designed to be, uh, to take a nap after lunch.

    11. RC

      Yeah.

    12. SP

      Uh, so, um, early afternoon, late afternoon. Uh, so, so that's when, if you think about it, although we have access to now air conditioning and cooling, but our ancestors didn't have that access. So it is to be very hard to go outside, outdoor.

    13. RC

      Mm-hmm.

    14. SP

      And for most of the human history, only in the last 35,000 years, uh, humans moved away from the equator to go north or south. But equator, that area used to be pretty hard, so we are designed to take the nap-

    15. RC

      Yeah

    16. SP

      ... early afternoon nap. So, so it's, it's already imprinted [laughs] in our genome to take a nap.

    17. RC

      Hey, that, uh, I... You know, for me, I'm a fan of naps.

    18. SP

      Yeah.

    19. RC

      I appreciate, you know, uh, for, for many of our jobs we're unable to, but certainly at weekends-

    20. SP

      Yeah

    21. RC

      ... man, I love a nap.

    22. SP

      Yeah.

    23. RC

      You know, I will get up early, but I also like a, a-

    24. SP

      Yeah

    25. RC

      ... an, an early afternoon post-lunch nap. And-

    26. SP

      Yeah

    27. RC

      ... I guess culturally, I grew up with seeing my dad doing it, you know, and so it's kind of... Or when we'd go to India every other summer, I'd see my family take naps after lunch.

    28. SP

      Yeah.

    29. RC

      So I kind of... It's ingrained in me. Um, and if it's early enough... And I, I, I've been recommending the naps. I know there's a lot of controversy around naps. I personally find that as long as the nap isn't taken too late-

    30. SP

      Yeah

Episode duration: 2:04:00

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