The Fasting Doctor: “Fasting Cures Obesity!”, This Controversial New Drug Melts Fat, Fasting Fixes Hormones! Skip Breakfast!

There seems to be endless ways to lose weight and yet none seem to work, but could it be that there was one health metric that held the key to long term weight loss? Dr Jason Fung is a nephrologist (medical expert specialising in kidneys) and world-leading expert in intermittent fasting and low-carb diets. He is the author of bestselling books such as, ‘The Obesity Code’, ‘The Diabetes Code’, and ‘The Complete Guide to Fasting’. In this interview, Steven and Dr Jason discuss everything from the history behind dieting myths, how insulin causes weight gain, why you don’t need breakfast, how obesity is genetic, and the power of fasting. You can purchase Jason’s book, ‘The Diabetes Code: Prevent and Reverse Type 2 Diabetes Naturally’, here: https://amzn.to/47K90z0 Follow Jason: Twitter - https://bit.ly/429c5rw Instagram - https://bit.ly/3Szn6iJ YouTube - https://bit.ly/4b0zfnT Follow me: https://beacons.ai/diaryofaceo Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  This calories in, calories out model doesn't work at all. If you're trying to lose weight, what you need to do is- Dr. Jason, um- The founder of intermittent fasting, whose influential work could be the key to a healthier and even longer life. Every continent is seeing this increase in obesity, but we put the blame on the individual. The problem is there's something wrong with the message we're giving people, and I can go over a few examples. First of all, exercise is really good in a number of ways, but in terms of weight loss, it's actually a very, very small effect. The whole idea that you need to eat as soon as you get up is just false. We know them twin studies that 70% of your risk of becoming obese is due to genetics,

• 0:44Speaker 00

  but it doesn't explain why the population became much more obese. And we know that you can't cure obesity by saying eat fewer calories. It's about fixing the hormones that are behind the calories. If you want to lose body fat, you actually need to extend the period of time that you're not eating, so you do some intermittent fasting. There's all this data showing that fasting activates the body, it increases your energy and your concentration. A treatment available to everybody for free, and it will be healthier for us.

• 1:13Steven Bartlett?

  So I need some advice then. What does your fast look like? What food should I be giving my body? And in what proportions?

• 1:19Speaker 00

  The first thing you gotta do is-

• 1:23Steven Bartlett?

  I've got to talk to you about these new injections people are getting to lose weight.

• 1:27Speaker 00

  I think-

• 1:38Steven Bartlett?

  Dr. Jason.

• 1:40Speaker 00

  Hey Stephen, how are you?

• 1:41Steven Bartlett?

  I'm really, really good. This book here, The Obesity Code: Unlocking the Secrets of Weight Loss. Why did you write this book? What was the sort of driving motivation behind committing what must have been a very long part of your life to this subject matter?

• 2:00Speaker 00

  It was actually a very interesting sort of journey of discovery for me. So I did my training in nephrology, which is kidney disease. So I'm a kidney disease specialist. And I thought about weight loss sort of very conventionally, sort of calories in, calories out, just watch what you eat sort of thing. And that's what's taught to all doctors is that it's extremely unhelpful for people. It doesn't work at all. It doesn't work for patients and it doesn't work for doctors even, right? So doctors who want to lose weight. They don't, they don't use calories in, calories out because it doesn't really work. And we all know this. Every person has sort of counted their calories and almost all of them fail to succeed.

• 2:44Speaker 00

  So the whole point was how to get people to lose weight. And so I started to look into the literature and I started to read about it and so on. I got very, very interested in it. And again, I started to become very unhappy with the discussion about calories in, calories out, because the whole point was that people had this idea that it was energy balance, right? And there's this sort of energy balance equation, which is calories in minus calories out equals body fat, right? Because body fat is a way to store calories. But that's not a very helpful sort of description of how to approach the problem, right?

• 3:27Speaker 00

  The problem is not that people didn't realize that they had to eat fewer calories or increase their calorie expenditure. The problem was why were they eating more calories than they could expend, right? And it's because the body is, is being told to store energy, right? That's the way it is. That's why you're taking in more calories or you're storing more calories is because your body has hormones that tell you to store calories. So there's a hormone called insulin, for example. And if you give people insulin, so inject them with insulin, which is a drug for type two diabetes.

• 4:07Speaker 00

  Almost everybody gains weight. So if you give somebody insulin, they gain weight. If I gave you insulin, you would gain weight. It has nothing to do with the, you know, your willpower, for example. If I gave you insulin, you would gain weight. Why? Because I'm giving your body the instructions to store energy.

• 4:24Steven Bartlett?

  So you're saying that weight gain and obesity in particular isn't a function of calories in, calories out. It is a function of hormones.

• 4:34Speaker 00

  It's a function of hormones and it's sort of, you have to think about it in sort of levels, right? So calories in, calories out is true. So body fat is a storage, is a way to store energy, which is calories equals calories in, calories out. But that's not the real question. The question is, why are you storing more calories than you're expending? And it's because you're telling your body to do so. So for example, if, if you take another equal, I'll give you an analogy. Say alcoholism is alcohol in minus alcohol out, right? Same, same idea. Or if you have a room, it's the number of people, how, how full it is, is how many people enter the room or exit the room, right? So same, same idea, right?

• 5:19Speaker 00

  It's absolutely true. So alcohol in minus alcohol out.

• 5:22Steven Bartlett?

  Equals how drunk you are.

• 5:23Speaker 00

  Equals how drunk you are. So alcoholism. So can you simply cure alcoholism by telling an alcoholic, oh, just drink less alcohol than you expend? It's like, yes, you can say that and it's absolutely true, but it's not useful in any way because you've never gotten to the really, the deeper understanding of why that person is taking in more alcohol, right? You have to get to that next level and say, well, you know, it's like going one level deeper. Why? Why are they drinking more alcohol? Well, maybe they're depressed. Maybe they're addicted. Deal with the addiction. That is the way to deal with alcoholism. You can't cure it just by saying, drink less alcohol. The same way you can't cure the obesity by saying,

• 6:06Speaker 00

  eat fewer calories because you're not understanding why the body is, is storing more energy.

• 6:14Steven Bartlett?

  With the amount of information we now have, the amount of science we have, one would expect that obesity levels would be coming down.

• 6:20Speaker 00

  Yeah, unfortunately, if you think about the way most people think about it, it's mostly still in calories, even in the academic centers. They all think about sort of calories, how to get calories down, how to reduce calories. And I always say, well, it's not about the calories, right? It's about fixing the hormones that are behind the calories. Because you can choose to eat fewer calories. Yes, that's true. But you can't, but you have to ask yourself, why are people eating so many calories, right? Well, it's because they're hungry. You can't choose to be less hungry. And therefore, you have to really talk about controlling the hunger and controlling the hormones, which are behind the calories that you eat. And that's going to be much more successful to you.

• 7:05Speaker 00

  If you take two different foods, equal number of calories, and you eat them, the hormonal response to those calories are completely different. So you eat two slices of white bread and jam. All that energy, so insulin spikes up because it's very high in refined carbohydrates. All that energy goes straight into your body fat, and you've left none of it for, for, for energy for your day. By 10:30, now you're ravenous, and you go get yourself a low-fat muffin. Again, pure carbs, insulin spikes up, all of that goes straight into your, your fat stores. Why? Because you told it to. Remember that when you eat white bread or muffins or refined carbohydrates, you're going to have this insulin spike,

• 7:50Speaker 00

  which is going to tell your body to store energy. If you eat an egg, you don't get that spike in insulin. So that, that energy that you've taken, those calories are there. You can use it. And so what happens? That keeps you full during the day. If you're telling your body to immediately store those calories as body fat, well, guess what? Over time, you're going to gain body fat because you told your body to do that. If you eat the egg and insulin's not spiking up, well, you haven't told your body to store that energy. So it's going to be around for you to use all day long.

• 8:20Steven Bartlett?

  And you won't be hungry.

• 8:21Speaker 00

  And you're not going to be hungry because your body's like, why do I need to eat again? Because you know, you're you, you basically have taken the energy that you need. I've got it available, right? It's sort of like if you go to the grocery store, right? You can store food in the refrigerator. Suppose you go to the grocery store, put all your food away, lock it away in the refrigerator. Now you have nothing to eat, right? You're going to say, oh, I need to go out and get some more food, right? Same thing with your body, right? So if you take food, but you've also spiked up your insulin, you're going to lock away all those that energy immediately into into your fat stores. It's not going to be available for you to use. Well, you're going to say, I'm going to go out and get more.

• 9:05Speaker 00

  So you haven't controlled the hunger. That's going to lead to the caloric intake, which is going to lead to the weight gain.

• 9:12Steven Bartlett?

  People look at this through an evolutionary lens and say, you know, we just didn't have this much food. So it's the abundance and ease of access to food. It's the fridges that we now have. It's the, you know, we never had fridges in our homes. So people point at it and go, well, that's why people are getting gaining weight. And, you know, we're suffering with obesity at epidemic levels, which is because there's more supply. And the brain is taking advantage of it. Because once upon a time, if we didn't eat that jam and toast, then we would have, you know, maybe not have been able to find food for another two weeks or something.

• 9:46Speaker 00

  Yeah, I don't think that's the whole story. Because if you think about it, and people, again, make that assumption that we don't have any control over our body fatness, right? So they say, well, it's available, so you're going to take it, right? In fact, that's not true. Because we actually have a number of different hormones that tell us to stop eating. Okay, so if you eat, you cannot simply keep eating and eating and eating, right? If you go to an all you can eat buffet, at some point you have to stop because you're full. Right? So there are systems, very powerful systems, within our body that tell us to stop eating.

• 10:28Speaker 00

  So you eat food, there are stomach stretch receptors, for example. So as your stomach stretches out, it sends a signal to your brain and says, stop eating. If you eat a lot of protein, it activates a hormone called peptide YY, which tells you to stop eating. If you eat a lot of dietary fat, you activate a hormone called cholecalcinine, which again tells you to stop eating. And these are very powerful. If you look in the wild, there are no obese antelope, there are no obese lions. Why? Because how much body fat you're you carry is actually very important. If you are obese as an antelope, you're gonna get eaten. If you are an obese lion, you're not gonna catch any food. So therefore, it's gonna correct itself.

• 11:12Steven Bartlett?

  So if I overeat now, my body will basically overcompensate by burning off the extra calories.

• 11:18Speaker 00

  It absolutely. So if you eat a huge meal, right? Do you eat, you know, you go to a big wedding or something like that? You eat a huge meal, the next day, you're probably not that hungry. If you eat a giant steak, so you're activating all these satiety hormones, peptide YY, cholecalcinine, you're eating all this food, well, you may not be hungry for the next day.

• 11:41Steven Bartlett?

  So that means that my body has some kind of baseline weight?

• 11:45Speaker 00

  Yeah, it will know whether you should eat more or less. So there's a this concept called the sort of body set weight, which is a sort of thermometer. That is, your body sets a weight that you should be at. And if you go above that weight, or if you eat too much, it will activate hormonal systems to bring it back down. If you don't eat enough, it will also activate hormonal systems to bring it up. So it's like a thermostat that you set you have in your room. For example, you set the the room temperature. If it's too hot, you're the the room activates the air conditioning. If it's too cold, it activates the heat. Your body actually acts the same way.

• 12:26Speaker 00

  If you gain too much body fat, your fat cells, for example, will produce leptin, which is another hormone. The leptin tells your body to stop eating.

• 12:36Steven Bartlett?

  That's really interesting. So in the case of obese people.

• 12:39Speaker 00

  Their set point must just be really high. Yes, and that's the crux of the matter. Why is that set point being overridden? Just like if you have a room that's too hot and you look and you say the thermometer is set for room temperature, why is it so hot in here? Then you can say, okay, well, what's the problem? And the problem is not, you know, heat in versus heat out, right? That's, that's a very simplistic way. Same thing, if your body has too much body fat, you gotta then think about, why are you overcoming the normal compensatory mechanisms that are happening, that are stopping you from eating? A lot of it relates to processing of foods, of course. So if you take out, so remember, I talked about stretch receptors in the stomach, right?

• 13:23Speaker 00

  So you eat natural, natural foods, there's a natural break. It stretches the stomach, you stop eating. Well, what's one way? Pull out all the fiber, process the foods, turn it into, say, a very fine dust. That means it's absorbed extremely quickly into the bloodstream. So that means that pure, you've got pure carbohydrate, basically mainlining it into your IV, like, like an IV. Your glucose spikes way up, your insulin spikes way up. It's completely unnatural, right? If you eat pure carbohydrate instead of eating it with, you know, proteins and fats, it's gonna go, it's gonna shoot way high. That's unnatural. And that's gonna overcome the natural, the tendencies for you to stop eating.

• 14:08Speaker 00

  So, you know, you've, you've basically overcome that, that, that, that protective mechanism because you've ultra-processed the, the carbohydrates. If you don't eat any protein, if you don't eat any fat, you're not activating peptide YY, which is the satiety hormone, you're not activating cholecystokinin. All of a sudden, you're eating, you know, 500 calories of white bread, but you have zero satiety. Or if you drink a Coca-Cola or a soda, for example. I've always, you know, thought about this. It's like, how can you take a thousand calories, for example, in one of those giant sodas you get at the ball game or something, and don't feel full at all? Whereas if you took a steak that's a thousand calories, you'd be like, I'm pretty full.

• 14:53Speaker 00

  I don't really feel like eating. You drink the soda, you're like, I really feel like eating some chips or popcorn or something. Why? Because it has zero satiety.

• 15:03Steven Bartlett?

  Interesting. So if I'm, if I've got a baseball stadium, what I want to do is I want to make sure people get a soda. Because then they'll also buy the chips. But if they just eat the chips, you know, maybe they won't buy anything else. But the soda is gonna increase my revenue. Because it'll basically just pass right through them.

• 15:23Speaker 00

  They'll pass right through them. They're gonna store all that energy, those calories, but they're gonna want more. Because you haven't made them full. Right? So the, the, the whole point is that you have to think more than about the calories. There's more there than just the calorie story. There's this whole hormonal balance.

• 15:39Steven Bartlett?

  You're saying that overeating isn't just a choice, it's a hormone driven behavior?

• 15:43Speaker 00

  It's a hormone driven behavior. I mean, the whole thing about obesity is, is quite interesting to me because if you think about obesity, if you think about in the United States, which is where I get a lot of my data from. You know, you have maybe seventy percent of people overweight or obese, and it's going up every year. It's been going up every year since nineteen seventy seven. And if you think about that, it tells you that the problem is not willpower. The problem is not the people. The problem is the environment that they find themselves in, the food environment that they find themselves in. Because you can take an analogy. Say you have a hundred children. One of them fails. Well, that might be the child. They didn't study. What if seventy of them fail? Would you say it's, it's each and every one of them's fault?

• 16:28Speaker 00

  Or would you say it's more likely that it's the teacher's fault? I think it's more likely that it's the teacher's fault. So if we have a hundred Americans and seventy of them are obese, the problem is likely not an individual willpower problem. The problem is likely that there's something wrong with the message we're giving people, the information we're giving people, and the food environment that we're finding ourselves in, which is dominated by this sort of calories in, calories out thinking. And what's really unfair, of course, is that we put the blame. On the obesity or overweight on the individual. And we say, well, they let themselves go and they didn't watch themselves. They weren't careful. It's their fault.

• 17:11Speaker 00

  And that's the stigma that comes with this whole calories in, calories out thinking. Because we say it's their fault because they could choose what they eat. It's like, yes, they could choose what they eat, but they didn't choose the food environment that is telling them to eat all this ultra-processed food, that is making all this ultra-processed food available to them, that is telling them that all this ultra-processed food is good for you.

• 17:32Steven Bartlett?

  So leptin is this hormone that essentially brings down my hunger, makes me less hungry. Is it therefore possible that people are becoming leptin resistant?

• 17:44Speaker 00

  There is leptin resistance. The question again is why? And the way to think about it is it's sort of this sort of balance, right? So insulin, if you give people insulin, like if you think about causes of obesity, what causes people to gain weight? Well, if I give you insulin, you'll gain weight. If I give me insulin, I'll gain weight. So insulin causes weight gain, whereas leptin will cause the opposite. So it's sort of the seesaw. Body fat is nothing more or less than a store of energy, right? And you only store energy when your body tells you. Our entire body runs on hormones, right? Nothing happens without the hormonal system being activated. So insulin is pushing us to gain weight, leptin is pushing us to lose weight. And what's happening is that one is sort of overcoming the other. Insulin is overcoming the leptin.

• 18:28Steven Bartlett?

  If obesity isn't about a lack of willpower and it isn't just a case of people being lazy or all those things that sometimes some people stereotypically assert, I've also heard the counterargument that obesity is a function of our genetic makeup and we inherit obesity from our parents, you know? Is there any truth and merit in that?

• 18:50Speaker 00

  It's yes and no. So yes, there is a very strong sort of genetic predisposition to obesity. So if you take, you know, somebody with a family history and look at the genetics, about 70% of your risk of becoming obese is due to genetics. And we know that from twin studies, for example.

• 19:10Steven Bartlett?

  What do we know from twin studies?

• 19:11Speaker 00

  If you take twins and raise them sort of in different environments.

• 19:17Speaker 00

  You know, they actually turn out very similarly. So we know that there's a genetic component to obesity. So when they they sort of do the calculations, they say about seventy percent of obesity is sort of genetically related.

• 19:31Steven Bartlett?

  So if you take a twin that comes from originally a family that were obese, and you put them with a family that are not obese.

• 19:40Speaker 00

  Yeah.

• 19:40Steven Bartlett?

  The child will still likely become obese, even with the family that are not obese.

• 19:46Speaker 00

  Yeah, so this was done, and obviously, they they had twins that were sort of separated at birth. Compare them after they've grown up and say, what's the sort of correlation between the weight of the two? And it's about seventy percent. So you have somebody who's very overweight and, you know, twin A goes into one family, twin B goes into a second family. You know, twin B is going to be more prone to gaining weight, even if they're with a thin family, right? So the environment has some role, but it's it's the genetics have a very large role, too.

• 20:20Steven Bartlett?

  Seventy percent.

• 20:21Speaker 00

  About seventy percent is genetic. So there is. However, the part that's important is that that doesn't explain why we have obesity in the last forty to fifty years. Because the genetics of the world population has not changed. So if we're seeing more obesity now, and remember, this is not a USA problem, it's a worldwide problem. We see it in Asia, we see it in Europe, we see it in America, we see it in South America, we see it everywhere. We see it in Africa. So every continent is seeing this increase in obesity. Therefore, it's not due to this recent change within the last fifty years is not due to a change in genetics.

• 21:05Speaker 00

  So while, yes, it's true that there is a strong genetic component, that explains my risk of, say, obesity compared to yours, but doesn't explain how the population of the United States, for example, all of a sudden became much more obese in general.

• 21:22Steven Bartlett?

  So you're saying this is really about a predisposition, which basically means your genetics make you more or less likely, for some reason, which is a genetic reason, to become obese when. You make certain lifestyle choices, but that is a predisposition, which means that, and I guess your work asserts that the predisposition relates to your hormones' response to the foods that we eat. So really, it's really a genetic response to foods, which is based on your hormone.

• 21:55Speaker 00

  We all have a certain genetic sort of predisposition to obesity, right? So all of us have a certain risk. Some people, obviously, they eat whatever they want and they don't gain weight. We all know people like that, right? And some people sort of look at a muffin and they gain weight. So you have that genetic predisposition. So that explains the difference between two people, but it doesn't explain the difference within an entire population. Like, if you take the entire population of the Earth, or even of America, or whatever, the genetics haven't changed sufficiently of that entire population to say why there's more obesity now than before.

• 22:31Steven Bartlett?

  So we're inheriting our parents' hormone response.

• 22:34Speaker 00

  Yeah, but we're, we're, the hormone response that we have is going to be dependent a lot on genetics, but the food choices we're making are different than our, our parents'. So they're eating different things. If you think back about what your grandmother ate and stuff, it's different than the food environment that we find ourselves in right now. And that food environment is creating this sort of, is sort of increasing the risk over, over time. That's the sort of what, what we need to try and figure out and why we need to have a deeper discussion as opposed to calories, because we've been having this sort of calories discussion for, you know, 30, 40 years. It just hasn't been very helpful.

• 23:17Steven Bartlett?

  You call it a deception. You say, in part two of your book, you say, "The calorie deception", and you say, "There are five wrong assumptions about obesity and weight loss. The calorie, calorie in, calorie out are independent of each other, so won't trigger one another." And this interesting point about the basal metabolic rate being stable. Is that in essence because people, you know, people will often say, "I have a low metabolism", it's kind of like a word in culture. If someone is obese, often the... The diagnosis is they have a low metabolism.

• 23:48Speaker 00

  Yeah.

• 23:48Steven Bartlett?

  Is there any merit in that? Is that true?

• 23:50Speaker 00

  Oh, absolutely. The question, so when you think about so body fat, you think about the energy balance equation. Body fat equals calories in minus calories out. This often leads people to say, well, just eat 500 fewer calories and you'll lose a pound of fat per week. It's unquestionably false because every single study that we've done over the last 50 years shows that if you eat 500 fewer calories, then over time, depending on what foods you're eating, eventually your body will just burn 500 fewer calories. So that's your basal metabolic rate, the number of calories that your body is expending in one day. So we see this in almost every single study.

• 24:33Speaker 00

  We've known about it for like 80 years at least. You eat fewer calories, your body burns fewer calories. Well, that's going to limit how much weight you're going to lose, right? So this idea that just eat fewer calories will automatically lead to weight loss is completely false because we know that eating fewer calories leads also to burning fewer calories. So you eat 500 less, your body burns 500 less and you're not losing any body weight.

• 25:03Steven Bartlett?

  So I go on a diet, let's say, because I'm trying to lose weight. My metabolism lowers to meet the calorific restriction that I've imposed on myself.

• 25:13Speaker 00

  Yeah.

• 25:14Steven Bartlett?

  What then happens when I come off the diet? Does my metabolism stay?

• 25:19Speaker 00

  Generally, yes.

• 25:20Steven Bartlett?

  Low?

• 25:20Speaker 00

  Yeah. So that's that yo-yo dieting effect. So say you start with 2,000 calories in, 2,000 calories out. You're not gaining weight, you're not losing weight, right? Now you decide, okay, I'm going to go on a diet. So you go down to 1,500 calories, thinking that you're going to burn 2,000 and the body fat's going to provide 500, right? That's how you balance that equation. However, if you eat the wrong foods and you're eating all the time. So you're eating 10 times a day, eight times a day, like people say you should. You're eating low fats or you're eating tons of carbs, you're spiking your insulin. Insulin prevents you from burning body fat. Okay, so we've, again, we've known about this for 80 years. So now you eat 1,500 calories, but you're keeping your insulin levels really high.

• 26:04Speaker 00

  So fewer calories, but lots of high carb foods, eating all the time. Insulin stays high. You're taking in 1,500. Your body is now burning 2,000, but you can't burn any body fat. So the calories that are stored in your body fat cannot be, cannot be sort of taken out. It's like it's in the bank and the bank is closed. You can't take it out. So what's gonna happen? Well, you don't have a balanced equation. So that cannot, cannot happen. So what happens is that in order to balance that equation, because your insulin levels are high, you're eating 1,500 calories coming in. Your body can only burn 1,500 calories. Your metabolic rate has just now gone down by 500 calories. And guess what? You're not losing any body fat.

• 26:48Speaker 00

  So that's an example of how the whole, the calories idea is completely wrong. Because if you continue to do that, what's gonna happen over time is that you, you get tired because you're burning fewer calories. You don't have enough energy to generate body heat. So you're cold, you're tired, you're hungry. So you say, okay, I'm gonna go to 1,800 calories. So now you're eating 1,800 calories, but you're only burning 1,500 calories. Guess what? You gain weight. And you say, but how can I gain weight? I'm eating less than I did. Yes, you are eating less than the 2,000 calories you used to eat. You're eating 1,800, but you're eating the wrong foods, very high insulin foods. So therefore you're going to gain weight. In fact, everybody says that.

• 27:33Speaker 00

  And, and all the, all the nutritionists, all the doctors, they just don't believe them. They say, you're lying, you're cheating, you're eating more than you think.

• 27:41Steven Bartlett?

  So this explains something that happened with one of my friends, which always puzzled me. He swears by the calories in, calorie out thing. I've spoken about him a few times. He posts about it online as well. And he, he actually managed to get a, pretty much like six pack abs, pretty much. And at the time, it appears that he was eating a lot of Domino's pizzas, a lot of pizzas. And I was thinking, how is this guy eating all these pizzas, but he's using this calories in, calorie out thing? And then when the pizza stopped,

• 28:09Speaker 00

  Yeah.

• 28:10Steven Bartlett?

  there was this yo-yo effect.

• 28:11Speaker 00

  Yeah.

• 28:12Steven Bartlett?

  Where he managed to get to basically what I'd describe as a six pack or thereabouts. And then stopped eating, stopped the diet per se. And then there was this big yo-yo effect, which I imagine is what you've said there. What he's done is he's lowered his metabolism. Then when he goes up just a little bit.

• 28:30Speaker 00

  It all comes back.

• 28:31Steven Bartlett?

  It all comes back and then some.

• 28:33Speaker 00

  And then some. Yeah, absolutely.

• 28:34Steven Bartlett?

  So this form of dieting is actually, over the long term, probably going to make you gain weight.

• 28:39Speaker 00

  Oh, it's very detrimental. And that's what yo-yo dieting, we all know it's very detrimental. But think about it differently, right? So let's take a different example with the same calories, which is why I keep saying you have to think about more than the calories. You have to think about what the hormones are, because that's the instructions to your body. Food contains calories, energy, but it contains instructions as to what to do. So let's take an example. You're eating 2,000 calories in, 2,000 calories out. Now you go on a diet, you want to, you take in 1,500. But what you do is you do some intermittent fasting. When you fast, insulin is going to fall. That's the whole point. Insulin is a hormone that goes up when you eat. It goes down when you don't eat, right? So when you eat, insulin goes up. Your body wants to store energy.

• 29:23Speaker 00

  When you don't eat, insulin goes down. Your body says, I have no energy, I have no food coming in. Please take it out of storage. So now you take 1,500 calories, but you do intermittent fasting. So you're allowing your insulin levels to fall. Now, 1,500 calories are coming in. Insulin levels are low. Your body wants to burn 2,000 calories. It says, well, insulin levels are low. Let me take 500 calories from my body fat. Guess what? You have 500 coming from your body fat. You have 1,500 coming from your foods. You burn 2,000.

• 29:54Speaker 00

  It's a balanced equation. So instead of the opposite situation, so and you see that the calories are the same. You went from 2,000 in to 1,500 in. But what the difference was, you allowed insulin to fall, which allowed you to burn body fat. Right. It's the hormonal signal that says, please take energy out. Open up the doors so that body fat can come out. And this is the piece that's missing because people are all like, well, I'm this, I'm that. And it's like, well, why can't you burn the fat that's on your body? Cause there's 200, 300,000 calories of body fat. Why can't you access it? It's because you haven't activated the right hormones so that you can access it. So now, if you do intermittent fasting, you eat 1,500 calories.

• 30:39Speaker 00

  You take 500 calories out, your body's burning 2,000. Now, all of a sudden, if you go off your diet and you go back to 2,000 calories, guess what? You don't gain weight, you don't lose weight, same as before. Whereas before you go even to 1,800 calories, you lost weight. But the difference was, not the calories, it was always 2,000 to 500. The difference was you paid attention to the hormones that you're telling your body. And the insulin is sort of the primary hormone. There's actually a lot more. There's, you know, there's, there's, there's cortisol is a very important hormone. There's other hormones.

• 31:14Steven Bartlett?

  You mentioned burning calories there. One of the thoughts around the calories in calories out model is that you can just exercise. And if you burn a thousand calories exercising, then that gives you a little bit of a reserve there to eat more, for example.

• 31:29Speaker 00

  Yeah, and it's probably a very, very small effect for, for a couple of reasons. So we know that if you exercise, and I say this, exercise is really good for you in a number of ways. Flexibility, strength.

• 31:47Speaker 00

  Core, all kinds of things. So very, very important. But in terms of weight loss, it's actually very, very small effect. Why? Because one, the amount of calories you burn during exercise are simply not that high. So if you look at, you know, if you do walking, I mean, if you did eight hours of high intensity exercise, yeah, you're going to burn a lot of calories. But most people I deal with, which are sort of middle aged and higher, you're talking about sort of a quick walk or, you know, forty five, half an hour, three times a week sort of thing. And if you ever go on the treadmill and you ever watch the calorie counter on the treadmill, you know, it goes up very, very slowly, right? You'll do half an hour and it'll be up to like a hundred and twenty calories or something like that. Right?

• 32:33Speaker 00

  So that exercise really didn't burn off very many calories. It's the amount that you'd get in a couple of cookies, for example, right? So it's, it's just numerically, it's just very small. So if you're, you're taking in, if your body is normally using two thousand calories with your brain generating body heat, your heart, your lungs, your liver, they're using two thousand calories and now you go up to twenty one hundred calories. Well, percentage wise, it's not a huge deal, right? The other problem with exercise is that it tends to actually cause you to eat more. So again, we've had decades of study for this. If you exercise during the exercise, you have a loss, a reduced appetite.

• 33:16Speaker 00

  So you have exercise, it's called exercise induced anorexia. So in the middle of a basketball game, you don't suddenly go, oh, wow, I'm really hungry. Right? Because your, your blood is flowing in your, you know, in your muscles and so on. You're not thinking about the hunger. So hunger actually goes down during exercise. But after exercise, we see this rebound. So we see that people are actually more hungry after exercise. And if you're hungrier after exercise, it's going to cause you to tend to gain more weight. In fact, there's this very interesting study that was done a few years ago in Harvard, where they measured the sort of calorie difference that you get with, for, for children in certain activities. So they said, okay, what if a child is watching TV?

• 33:59Speaker 00

  What's the average caloric difference? And it was like plus one hundred calories per hour. So for every hour of TV. They're sort of positive 100 calories over time, right? And that makes sense, you're just sitting there. When you look at mild exercise, it's about the same. It's about positive 100 calories. So the only way that happens is that if that exercise is causing you to eat more, right? And you say, well, why are you eating more? It's like, well, because you're you're hungry. Like, the exercise is inducing you to eat more. And that's gonna make it difficult to lose weight.

• 34:33Steven Bartlett?

  You say in the book in chapter four, that 95% of weight loss is diet.

• 34:38Speaker 00

  Yeah, a- and that's the reason why exercise is very hard to exercise enough to lose weight. And and that's not to say that you shouldn't exercise. It's it you really should exercise, everybody should exercise. But if you're trying to lose weight, you still got to focus on the main topic, which is the foods that you eat, which is not just the calories. It's about the types of food that you eat, which is going to affect the hormonal balance, and also how often you eat. If you're eating all the time versus if you're eating only eating very infrequently, then you're going to have a different hormonal balance that is going to affect your weight as well.

• 35:18Steven Bartlett?

  An American survey of more than 60,000 adults and children revealed that in 1977, most people ate three times a day. By 2003, most people were eating five to six times a day.

• 35:31Speaker 00

  Yeah.

• 35:34Speaker 00

  Yeah, this is the whole idea of sort of eating all the time. And this I find fascinating because it was this sort of inadvertent change in our diet that we never talked about, right? So in 1977, we told people, eat lots of carbs. Okay, so we know that, that's in print for sure. The American government said eat 55 to 60% carbs, eat less fat. What happened is that, you know, in 1977, people ate breakfast, lunch and dinner. No snacks. If you wanted an after-school snack, your mom said, no, you're gonna ruin your dinner. If you wanted a bedtime snack, your mom would say, no, you should eat more at dinner, right? No problem.

• 36:16Speaker 00

  But what happens is that as we started to eat sort of a lot of carbs, what happened is exactly as what we discussed before, you eat two slices of bread in the morning with jam. You have no satiety, insulin spikes way up, glucose spikes way up, but then it crashes.

• 36:33Steven Bartlett?

  So you get hungry again.

• 36:34Speaker 00

  Then you get hungry at 10:30. So you go around looking for a low-fat muffin. And it was because, you know, you know, your, your, your, your sugars are going down, your insulin's going down. So now you're eating mid-morning snack. Then you eat a big plate of pasta. Then you get ravenous at like 3 o'clock. So you go find yourself some crackers or something like that, right? And then now you're having a mid-morning snack. You're having mid-afternoon snack. Then you're having a bedtime snack. And that's the average American by 2003 is eating six, five, six times a day. But they're saying, hey, I'm eating so low fat. This must be the right way to eat. This must be good for me. So now this snacking becomes institutionalized. Whereas pre-1977 snacks are an indulgence, right?

• 37:18Speaker 00

  It's not something good for you. It's something bad for you, but hey, once in a while you, you, you indulge. Then it becomes institutionalized as something that every single one of us should be doing. And we should never be without food for more than an hour and a half. Let's think about this very simply, okay? So if you eat, your insulin's going to go up. Your body's going to store calories because you're told it to. If you don't eat or if you fast, your body is, your, your insulin's going to go down. You're going to bring those calories back out of storage, right? So you're going to burn calories. You eat, you store calories. You don't eat, you burn calories. Very simple. So why would you want to eat all the time? That makes no sense at all.

• 38:01Speaker 00

  If you want to lose body fat, you actually need to extend the period of time that you're not eating. In other words, extend your fasting period and get rid of all the snacks in order for you to have enough time that your insulin is low. When insulin is low, it's going to allow fat burning, which is going to allow you to pull those calories back out.

• 38:22Steven Bartlett?

  You're cited as being really the founder of modern intermittent fasting. And I've heard people talk about intermittent fasting on this show over and over and over and over again now, but.

• 38:35Steven Bartlett?

  The internet says that it really came from you. I know that intermittent fasting has been happening for thousands of years, but the idea of it as a tool for weight loss, they say it came from you.

• 38:44Speaker 00

  Because in 2013, 2014, really, nobody was talking about it from a medical standpoint. Like, what's happening in the body? Why is it good? Why is it bad? And really, I was for years, sort of this one voice in the wilderness that was saying like, hey, this is a tool for us. If you want to lose weight because it's important, then you can just set aside a period of time that you don't eat. At the time, people thought it was extremely bad for you. And I looked through all the literature and I said, well, why is it bad for you? And they had all these reasons. There's all these myths about intermittent fasting and how it's going to cause you to gain weight and be tired and hungry and all these sorts of things. I said, well, no, there's actually a lot of data here over the last, you know, 2000 years

• 39:29Speaker 00

  that we've used intermittent fasting, and they're simply not true. And I can go over a few of those. But that's why there was nobody talking about it at the time. And that's where I started to sort of bring it into the sort of public consciousness that this is a tool. That's all it is.

• 39:43Steven Bartlett?

  Were you attacked for that at the time?

• 39:45Speaker 00

  Oh, absolutely. Like, I got, I got attacked from all sides. I got, you know, doctors were coming after me, dieticians were coming after me. Everybody thought I was going to do so much harm. And the funny part was that, you know, as I think back, as I spoke to a lot of colleagues, a lot of colleagues would say to me, you know what? I used to do that when I was in training. We did that all the time. We'd go 24 hours without eating because we're in the OR or we're in the ER or we are busy. So we did that constantly and nothing bad happened. And I remember thinking, you know what? As a doctor, I actually tell people to fast all the time. If you have to go for surgery, you need to fast. If you're after surgery, you need to fast. If you do fasting blood work, you need to fast.

• 40:28Speaker 00

  So why is it that I'm actually telling people to fast all the time? And yet, for weight loss, you shouldn't fast? That doesn't make any sense. And physiologically, from a body standpoint, it doesn't make any sense. One of the things people talked about was, you know, it's going to make you eat more later. It's going to make you more hungry. Your basal metabolic rate is going to go down. This was one of the big myths of intermittent fasting. That's going to cause the so-called starvation mode, right? And this is the idea that your basal metabolic rate will fall so low that when you do start to eat, you're going to gain weight again. So I said, well, let's think about this. You can do a study where you take somebody, say you, for example, and you could fast them for four days and measure how much,

• 41:12Speaker 00

  how many calories they're burning, their basal metabolic rate on day zero before the fast, and measure them four days into the fast and see how many calories you're burning. So on day zero, they say you're burning, say, 2,000 calories a day. On day four of zero food, you don't eat any food for four days. They measure how much calories you're burning. Your body is burning 2,200 calories. Your basal metabolic rate didn't go down. It went up. Your body's activating itself during fasting, which is fascinating because if you're trying to lose weight, dropping that basal metabolic rate is death. Like, if you drop that metabolic rate, it's so hard to lose weight. That's what the calorie-restricted diets did.

• 41:55Speaker 00

  That's what the low-fat diets did, the eating all the time did. But when you actually fast, your metabolic rate went up. And we see this in study after study. And the reason is actually basic physiology. It's actually medical physiology, like first-year medical school stuff. When you don't eat, what happens in your body from a hormone standpoint? Is that your insulin's going to fall. You're going to allow your body to start using the calories that are in the body. At the same time, other hormones go up. So the sympathetic tone goes up, which is your fight-or-flight response. Your cortisol levels go up because, again, it's an activation. And your growth hormone goes up because those hormones are going to start telling your body to start pulling calories out.

• 42:40Speaker 00

  So you're actually activating yourself. Think about in the wild, if you see a hungry wolf, is that wolf just sort of, you know, all like lethargic? No, he's activated. He's actually more dangerous than any other wolf, as opposed to say, a lion who just ate. Because when you just eat, you just want to lie there. You know, you want to digest your food. You have no energy. So people say, wow, your metabolic rate's going to go down if you fast. No, the truth is actually the opposite. It goes up.

• 43:09Steven Bartlett?

  You've got me thinking about food as an instruction I'm giving my body. Because if I eat this food, it's going to have this impact on my hormones, which is going to have this impact on my body. So if we view food as an instruction to the body, we talked a little bit about the timings of eating and a little bit about fasting. I want to get into that a little bit more. But breakfast, I read that you didn't think most people need breakfast.

• 43:32Speaker 00

  Yeah, the whole idea that you need to eat as soon as you get up is just false. So there's this whole thing about breakfast. Now, you will always break your fast. Think about the actual word, right? Break fast. It's the meal that breaks your fast, which tells you that in the English language, we accept that your body should have a fasting period every day. Why? There's a period of time that you're supposed to feed, you eat, insulin goes up, you store calories. Then there's supposed to be a period of time that you fast. That's after dinner, until the next day's meal, which is breakfast, right? So say you stop eating at 6pm, you eat at 8am. That's a 14-hour period where your

• 44:17Speaker 00

  body is not eating, it's fasting, and therefore it's going to use calories, right? But the word breakfast tells us that that's actually a normal pattern, this normal cyclical pattern. You feed, then you fast, right? If you eat all the time, your body's just going to store energy and never have a period to burn energy. So Okay, well, what's gonna happen? You're gonna gain weight.

• 44:41Steven Bartlett?

  I read as well that breakfast eaters averaged 539 extra calories per day compared to those that skipped breakfast. And that's a finding that's consistent with other trials. That was on page 132 of the Obesity Code.

• 44:54Speaker 00

  Yeah, so the more often you eat in general, the more calories you take in. So if you eat three times a day, or six times a day, then, you know, if you eat three times a day compared to two times a day, for example, you'll in general eat less because it's harder to eat that, you know, big meal. So say you eat once a day versus three times a day. If you eat once a day, it's not always easy to eat three meals worth of calories all in one sitting because you get full.

• 45:24Steven Bartlett?

  Do you fast?

• 45:25Speaker 00

  Oh, I do that regularly, yeah.

• 45:27Steven Bartlett?

  And what does your fast look like? Because I've heard of all these different types of fasting, 36 hours, 72 hours, 14 hours.

• 45:33Speaker 00

  There's no rules for fasting. You could do, you know, it could be 16 hours. So 14 hours, remember, is sort of a baseline, 12 to 14 hours, right? That just means you're not eating after dinner. That's it. And so if you want to lose weight, that's probably not strong enough to make you lose weight because 12 to 14 hours is sort of just this baseline that people had in the 70s. So you can go to 16 hours, for example, and you shrink that by either eating breakfast a little later or eating dinner a little earlier. But you can do more than that. You can do, say, a 24-hour fast. You could eat two meals a day, say, eat between 12 and 6. That's a six-hour eating window. Or you could eat once a day, which is like a 24-hour fast.

• 46:15Speaker 00

  Or you could even go multiple days without eating because, again, your body is smart. Like, your body knows what to do. If you have all those calories sitting on your body, right, 100,000 calories, sitting in body fat, and you don't eat for three days, well, you need 6,000 calories. Well, you have 100,000, 200,000. So what's the problem? Take it out of your body fat. Let your body eat your body fat. That's what fasting is doing for you. And it's totally natural because that's what it's there for. That body fat is not there for looks, is there for you as a source, as a store of calories. So fasting just lets you use that. There's nothing wrong with it.

• 46:57Speaker 00

  People talk about hunger, for example, but again, hunger is very interesting because people think it's the amount of time that you haven't eaten, but it's not true. It's actually hormonally mediated. So if you think about hunger, I actually found this really fascinating. So if you look at studies of when people are the most hungry and the least hungry, on average, people are the most hungry at 8:00 PM and the least hungry at 8:00 AM. So in the morning time, you're actually the least hungry that you will be all day. That's just an average. And at 8:00 PM in the evening time, you are the most hungry. So 8:00 AM is the period of time that you've gone the longest without food. So why are you the least hungry?

• 47:41Speaker 00

  It's because it's hormonally mediated. When you wake up at 5:00 AM, your body actually has this surge of hormones, growth hormone, cortisol, and sympathetic tone, which is already getting you prepared for the day. It's starting to release some of the stored glucose from your body fat, from your sugar stores at 5:00 AM. So your body has already prepared you for the day ahead without you even doing anything. That's why people in general are not hungry at 8:00 AM.

• 48:12Steven Bartlett?

  I've got to talk to you about these, um, these new injections people are getting to lose weight.

• 48:17Speaker 00

  Yeah.

• 48:17Steven Bartlett?

  And the role that they must be playing in our hormone balances. What are those bloody things called?

• 48:21Speaker 00

  GLP-1s?

• 48:22Steven Bartlett?

  GLP-1s. There's another name for it, isn't there?

• 48:24Speaker 00

  Yeah, uh, well, there's the drug name, which is, uh, Ozempic is the, uh, is the American name. And these are all in a class called GLP-1s. And essentially, again, very interesting because they essentially.

• 48:40Speaker 00

  Really reduce the appetite, which goes to show you that and people lose weight like a lot of weight and they keep it off.

• 48:47Steven Bartlett?

  I know very smart people that are using them.

• 48:50Speaker 00

  Yeah.

• 48:50Steven Bartlett?

  Like a billionaire friend of mine that's very big in a certain industry uses Ozempic. I know Elon Musk came out and said.

• 48:58Speaker 00

  He said he used it, yeah.

• 49:00Steven Bartlett?

  Ozempic as well.

• 49:02Speaker 00

  I don't, I'm not, I, I, I don't have any problem with the Ozempic because again, if you think about it, what it's telling you, the lesson it's teaching you about weight loss is that it's not about controlling the calories because the Ozempic doesn't burn any calories. It's about controlling your hunger. It's about that one level deeper. Why are you taking so many calories? So if you simply reduce the hunger, you're going to naturally eat fewer calories, which is going to cause weight loss. And that's what this Ozempic does. It really reduces your appetite to very low levels.

• 49:36Steven Bartlett?

  How?

• 49:37Speaker 00

  It, it's, it's this, this hormone called GLP-1, uh, which is a natural sort of hormone. It's, it's released mostly in the intestines and the distal intestine and the small intestine. And in response to certain foods, it, it goes up, right? So when you eat, the body has a homeostatic mechanism. So again, remember, you know, people think that we're just eating machines. We eat until, you know, we explode sort of thing, but that's not true. When you eat, you actually activate the GLP-1 along with other hormones. There's multiple hormonal systems. The GLP-1 is the one we're interested in. You activate GLP-1, which then sets into motion the, the instructions for you to stop eating, right?

• 50:19Speaker 00

  So the act of eating sort of sets in motion that whole feedback loop to stop, right? So this is homeostasis, which is trying to keep things at a proper level.

• 50:29Steven Bartlett?

  Does that mean if you eat slower? You'll be less, you'll eat less.

• 50:33Speaker 00

  Hmm, there's probably not, uh, yeah, probably it's true. Um, you know, although it's probably mostly true that if you eat really, really fast, that you don't have enough time for this sort of homeostatic mechanisms to kick in. So you don't have enough time to stop eating. Um, but the GLP ones then go to the brain. So they do certain things, they help with digestion. So they increase insulin response. And then they go to the brain, it crosses um, the, the, the, the blood brain barrier. So the GLP ones gets released by the act of eating, goes into the brain, crosses and is active um, in the sort of midbrain area that tells your body to stop eating.

• 51:15Speaker 00

  What these GLP ones do, of course, is that it's a uh, it, it gives you the hormone that tells you to stop eating, even though you haven't eaten. It's sort of, that's, that's the way the drug works. So then what people tell you is that, you know, they're just not hungry. And if they're not hungry, then they don't eat. And when they don't eat, of course, insulin falls and you start to burn calories and lose weight. But it wasn't about controlling the calories, it was about controlling the hunger. That was the important part of it. It's the hormones, right? Every successful drug to gain or lose weight, right? Is a hormone, it's a hormone base, because that's instructions to the body. Food is energy and food is instructions.

• 51:59Speaker 00

  You change the instructions and you, you change the hormone.

• 52:02Steven Bartlett?

  This whole history of fiber thing has been so interesting to me because uh, in the last six months, so many of the nutritionists I've spoken to have really impressed upon me that we are fiber deficient. And I'm wondering how that happened.

• 52:15Speaker 00

  Um, well, I think it was part of the processing uh, thing. So taking out fiber is a great way to make foods more. Appealing, if you will. So what happens is that if you take flour, for example, and you have a lot of fiber in it, then the digestion is slowed. So what you get is a slower rise. So you take flour and you put a lot of fiber in it. Well, instead of having this huge spike in insulin, which you're going to get, it's a much slower spike in insulin. When you have the huge spike in insulin, it basically overloads your system and it makes you feel, you know, gives you this big hit. Sort of like if you have like cocaine, for example, you know, it's,

• 53:00Speaker 00

  it's turned into a very fine powder, then you snort it. So you get this massive sort of spike. Same thing with, you know, carbohydrates. If you don't have any fiber, you, you pull all the fiber out by processing, you get this massive sort of unnatural spike and your body says, oh, that's great. It tastes great. I really love it. And you get people who are sort of addicted to it because that big spike is then going to release dopamine. And dopamine is a pleasure hormone. So you eat, you know, cookies or whatever, highly processed foods, you get this sort of pleasurable response and that makes you crave it. If you have

• 53:40Speaker 00

  a lot of fiber, it acts almost sort of like an antidote to that carbohydrate because you're slowing down that release. What foods are high in fiber? Well, mostly unprocessed foods. So the things like beans and if you're having, if you're eating whole grains, for example, compared to others, then it's going to have a reduction in the speed of absorption. So it's again, not about the calories necessarily, or even necessarily about the carbohydrates, because you're still eating the same amount of carbohydrate, but you're slowing down the speed at which is absorbed, which is going to change the instructions that you give your body. If you have a massive spike in glucose, you get this massive dopamine surge, right? And your body's like, yo, love it.

• 54:26Speaker 00

  Then the next time, you're like, okay, give me that refined carbohydrate.

• 54:30Steven Bartlett?

  What about protein? Because we we tend to think of protein as something that, you know, is super great for weight loss.

• 54:35Speaker 00

  Yeah, protein is probably sort of inter it it's not bad. I mean, the main thing is cutting down the carbohydrates. But, you know, in the obesity code, I really talk about cutting the processing down because proteins usually don't come as pure protein, right? In nature, you never find like, you know how you have like whey powder protein or whatever you get. The only way you can do that is by processing the heck out of food to get some kind of pure protein. It doesn't exist in nature, like it almost doesn't exist in nature. Maybe there's a few examples. But when you eat meat, you think, okay, there's a lot of protein, but that's actually a lot of fat in there, too, right?

• 55:19Speaker 00

  If you eat anything else that has protein, it's it's rarely all protein. You know, very lean meats like chicken breast and stuff are going to be higher in protein, but there's still a lot of other stuff in there. And it's very rare that somebody will eat just all pure hundred percent protein. It tends to be hard to eat, like the fat brings a lot of flavor and so on. So it's a bit of an unnatural way to eat. Sure, if you if you're to eat a lot of protein, it does spike insulin, so it does have some effect to gain weight, but it's actually a very inefficient macronutrient. That is, you're there's three macronutrients, there's carbohydrates, there's fat, and there's protein. Your body stores energy or calories in two ways.

• 56:02Speaker 00

  There's glucose, which is carbohydrate, and it stores it as body fat, which is fat, right? It doesn't protein is not a way for the body to store energy. So when you're eating a lot of protein, it's very difficult for it to turn it into a storage mechanism, like, you know, so you eat glucose, and you eat fat, you can store glucose and you can store fat, but you eat protein, but you don't really store it as a source of energy.

• 56:28Steven Bartlett?

  So if all foods then increase our insulin levels.

• 56:33Steven Bartlett?

  I guess the best solution is to fast.

• 56:34Speaker 00

  Uh, fasting is certainly one way, but just changing the foods to other ones. Because if you look at the insulin uh release in processed foods versus unprocessed foods, there's a huge difference. So if you eat sort of uh highly refined foods like white bread, for example, then you're going to have a very different response in insulin compared to sort of um a whole, a whole food. So uh unprocessed foods in general, your body knows how to handle. Like, we've been eating them for thousands of years. But certainly, anytime you eat, your insulin's going to go up. You're giving your body instructions to store energy. So the solution is to eat less often.

• 57:18Steven Bartlett?

  What if you do a juice fast?

• 57:20Speaker 00

  Juice fast, of course, is not a real fast because you're you're taking a lot of sugars.

• 57:24Steven Bartlett?

  What do you think of juice fasting?

• 57:27Speaker 00

  Um, generally, I I I think it's less effective than regular fasting, and it really depends on how much juice you take. If you take a lot of juice, you could easily get, you know, thousands of calories plus a lot of sugar. If you do it, you know, cucumber juice and stuff that's very low in sugar and kale juice, then it could be very, very healthy for you because there's vitamins and stuff there. So it all depends on how it's done. However, the um the fasting is a way for you to sort of clean out the body. So you can clean out the glucose. If you have excess body fat, you're you're going to use it, right? So again, way to clean it out. And then there's this whole process called autophagy, which is just fascinating. And autophagy is this, um, so it's been very topical because in 2016, one of the key researchers was given the Nobel Prize in Medicine.

• 58:11Speaker 00

  So it's it's a very important process that's been relatively recently discovered. And what they discovered is that when you don't eat protein particularly, but when you fast, your body activates this thing called autophagy, and it breaks down some of the subcellular organs, which sounds really bad.

• 58:29Steven Bartlett?

  Subcellular organs.

• 58:30Speaker 00

  Yeah, so you know, these are sort of like the organs within the cell. So it's not like the liver, but there's something called organelles within a cell. And some of that is broken down. So basically, these proteins and so on within the cell, your body gets rid of that. And you think, oh, well, that sounds really bad. But it's not. It turns out that it's very, very good for you because it's an opportunity for your body to get rid of all this old protein, old junky protein. And at the same time, remember that you're fasting, your growth hormone levels are shooting up through the roof. So like a, you know, two, three day fast, your growth hormone levels might go up five times. So you're getting rid of all the old stuff.

• 59:12Speaker 00

  Then when you eat again, you actually got growth hormone to produce new proteins. So in essence, you're getting rid of the old, you're bringing in the new. It's basically the process of rejuvenation. Could this be a very important way to get rid of some of the chronic illnesses of aging? And there's lots of data, you know, talking about, you know, Alzheimer's disease, there's talk, people talking about cancers, there's people talking about just general aging, you know, Dr. Chris Palmer, talking about mental disorders. We're all talking about insulin and overeating and diet as a really important component of not just diabetes and weight, but all of these diseases, mental illnesses, you know,

• 59:58Speaker 00

  chronic illnesses like Alzheimer's disease, neurologic illnesses. And there's all this data that suggests that autophagy and fasting is a way to activate autophagy could be actually extremely beneficial for you, which is fine when we used to do it. And, and, and, you know, what's so interesting is that people seem to have already known about it. Like you see it in almost every major religion. There's periods of fasting, right? It's like, why did they do that? Because it was good for them. Through trial and error, whatever, they realized that, hey, periodically abstaining from food makes us stronger.

• 1:00:43Speaker 00

  If you eat all the time, constantly, day in, day out, week in, week out, month in, month out, that's not that good for you. There are periods that you should feast, and there are periods you should fast. So religions set days, or weeks, or months even, where you should fast. So it's like, whoa, why did they do that? And are they just way ahead of us in terms of understanding the human body? Like, we get so enamored of our own intelligence and science and so on, that we think that they didn't know what they're talking about. Maybe they knew more about what they're talking about, and science is just catching up and saying, oh, this process of autophagy that you activate with fasting, this could

• 1:01:26Speaker 00

  be really important for longevity, for other things. I'm not saying you should do it like every month, or whatever. If you look at the way that people do it, they don't do it like, you know, they don't do like five days a month, or something. They do it once a year, once every few months. How long does autophagy take to kick in? Is it 72 hours, did you say? Nobody knows, but probably, and it depends on probably how much protein you eat. Protein is the key. Sort of when you eat protein, autophagy just stops. So low protein, you can activate it, and it's probably somewhere around 20 to 30 hours. So you'll see a lot of religions, for example, they'll have like a 24-hour fast, right? One day that you're not supposed to eat, or something like that. And maybe that's the way to cleanse your

• 1:02:10Speaker 00

  body, not just of the glucose and the fat, but also the excess proteins that are old, they're junky. I mean, you think about renovating your bathroom, or something like that, right? The first thing you gotta do, you gotta throw out the 1970s tub and the avocado green toilet. That's the first thing you gotta do. You gotta get rid of it. You gotta break down before you can rebuild better. Well, autophagy might be that way to break down some of the stuff that you actually can't break down any other way. If your body's full of all this junky protein... You can't get rid of it.

• 1:02:45Steven Bartlett?

  Is there an evolutionary explanation for the role of autophagy, do you think?

• 1:02:49Speaker 00

  I think there is, actually. I think there's a huge number of reasons why people do it. One of it, this whole idea that fasting actually activates the body, for example, is very interesting because I think it's like, if you're a caveman, for example, or cave woman, and it's winter and there's nothing to eat, if your body starts to shut down, then evolutionarily, you're going to die, right? Because you have less energy, you can't go out and hunt. So our body's just not that stupid. So what it does is says, okay, well, I'm going to give you more energy. So I'm going to activate the body, but then I'm going to change where you're getting your energy from. You're not going to get the energy from the food. You're going to get it from your body fat stores, which is your stored food, right? You stored food for a reason.

• 1:03:33Speaker 00

  So that's why I think some of the fasting has a lot of evolutionary benefits because it increases your energy, it lowers the glucose. So if you look at the blood glucose, the blood glucose goes down. So in times of stress and so on, your body actually naturally fasts. If you get sick, you get a flu or something, you stop eating. First thing you do, right? You just want to drink some water and stuff. Why? Because your body wants to lock down the glucose because the bacteria love glucose. Your body can run on fat, but the bacteria want the glucose. So you fast to lock down the glucose. So there's a lot of evolutionary reasons why the fasting might be good for,

• 1:04:15Speaker 00

  you know, bacterial infections, taking care of things, increasing your energy, increasing your concentration at a time that you're not, like when you're not eating, you're actually getting more mental capacity and more energy because you need it in order to go hunt.

• 1:04:30Steven Bartlett?

  Interesting. What is, what is the most interesting thing or the most, you know, you use the word interesting a lot or fascinating? What is the most fascinating thing that we haven't talked about?

• 1:04:42Speaker 00

  I think to me, the most fascinating thing is, other than for intermittent fasting, because a lot of the stuff we thought about, it was wrong. In fact, the opposite. But the most interesting thing, I think, is in the field of type 2 diabetes, because it's such an important disease. If you look at the number of people being affected with type 2 diabetes, it's skyrocketing. So we had, since the 1970s, an increase in obesity. Then we had an increase in type 2 diabetes. And I think the most fascinating thing, the most promising thing I've heard in a long time is that you can actually start to reverse this disease by changing the diet. And I think what's interesting is that you

• 1:05:27Speaker 00

  have to understand that type 2 diabetes is largely a dietary disease. And so we treated it with drugs for a long time. And if you give drugs to a dietary disease, well, you're never going to fix it, because you haven't identified the core problem and fix it. You need to change the diet to fix that dietary problem, then the disease goes away. And now we have data on intermittent fasting, for example, and also low carbohydrate diets. Dr. David Unwin published his data in the UK on reversing type 2 diabetes with reducing carbohydrates, which is showing that you can reduce about 50% of the people and put

• 1:06:07Speaker 00

  them into a completely drug-free remission state, like basically cure 50% of those type 2 diabetics, who are at risk of cancer, at risk of heart disease, at risk of strokes, at risk of blindness, at risk of kidney disease, nerve damage, infections. All these people you can fix, just by changing their diet, either cutting down their carbohydrates or using intermittent fasting. And it's free. And anybody can do it. I'm not talking about a drug that costs thousands of dollars. I'm not talking about a surgery which is only available to the 1%. I'm talking about a treatment, which is intermittent fasting,

• 1:06:51Speaker 00

  which is available to everybody in the entire world for free, and yet has the power to completely reverse their disease and make them so much healthier. So the question is, why don't we do it?

• 1:07:07Speaker 00

  I couldn't answer that question for you.

• 1:07:11Speaker 00

  I tried to do my part to tell people, but you know.

• 1:07:15Steven Bartlett?

  Did you know I was gonna ask you that question?

• 1:07:17Speaker 00

  Uh, no.

• 1:07:18Steven Bartlett?

  I was gonna ask you, why didn't we do it?

• 1:07:21Steven Bartlett?

  No, but what is it? Systems, incentives, money?

• 1:07:25Speaker 00

  I think it is. I think it's.

• 1:07:29Speaker 00

  You know, the real reason is I think that people are slow to catch new ideas. Like when people hear about new ideas, and I'm talking about academic doctors and so on. There's an intrinsic resistance to change. So I started talking about intermittent fasting, say 2016, when the obesity code was published. I talked about it, about reversing type 2 diabetes around the same time.

• 1:07:55Speaker 00

  And it's just, they're just very slow to say, hey, this makes a lot of sense. Because for them, they've invested so much in this calories in, calories out model. They've built their entire careers on saying that it's, it's your fault that you're fat, right? It's, it's the foods that you ate, it's the calories that you ate, instead of trying to get to a deeper understanding. So people are very reluctant to change. In fact, I mean, it's been 10 years and you see the public, the interest in intermittent fasting has skyrocketed. And yet, most doctors still won't prescribe it, they won't talk about it, they know nothing about it. There's, how much teaching do doctors get about intermittent fasting and why it might be helpful? Probably zero.

• 1:08:38Speaker 00

  Like, why? We have this amazing tool. And people, you know, doctors call it a fad, right? It's a fad diet. Well, it's been around for 2,000 plus years. That's a long, long, long fad, right? It's, it's proven effective. If you don't eat, you're gonna lose weight. What's simpler than that? If you don't eat, you're gonna use up your blood glucose, your diabetes will get better. What's wrong with that? It's not hard to understand.

• 1:09:04Steven Bartlett?

  The Diabetes Code, I've got the Diabetes Journal here in front of me. And put simply, it talks about step one being to put less sugar in and step two being burn the sugar off.

• 1:09:14Speaker 00

  Yeah.

• 1:09:15Steven Bartlett?

  And, and step one, which relates to putting more sugar in, is all about.

• 1:09:21Steven Bartlett?

  Low carbohydrate diets, right?

• 1:09:23Speaker 00

  Cutting down the carbohydrates. Yeah, that's that's one effective way of cutting down the type two diabetes. In fact, the American Diabetes Association and their sort of nutritional journals, they talk about having the most scientific evidence of any diet. There's no diet with more evidence for reversing type two diabetes than cutting down the carbohydrates.

• 1:09:42Steven Bartlett?

  And then step two about burning the sugar off, and that's where fasting comes into the picture.

• 1:09:46Speaker 00

  Yeah. I mean, if you think about it, there's there's it's not that hard to understand. Everybody can understand it. You don't eat, you're gonna lose weight, right? I mean, it's it's such a simple, powerful tool, but it threatens the whole apple cart. All these doctors, all these professors, which have built their entire reputations, all these systems that are in place.

• 1:10:13Steven Bartlett?

  Personal trainers.

• 1:10:15Speaker 00

  Yeah, personal trainers work on a different level because they talk about more exercise.

• 1:10:21Steven Bartlett?

  And calories in, calories out. I think when we talk about calories on this show, sometimes I think the people that get quite offended tend to be personal trainers because I think they would say they've got case studies of telling one of their clients to monitor their calories and they saw a reduction in weight. So they, for them, that means it works. There's calories in, calories out model.

• 1:10:46Speaker 00

  It, again, it is that, but it's a simplistic understanding. That's, that's, that's my whole point. It's sort of like if I were to say to you, why did the Titanic crash? Right? And most people would say, not hidden iceberg. Well, that's very simplistic. That's not the right answer. The right answer is it was going too fast. Right? If you think the right answer to why did the Titanic crash is because it hidden iceberg, you'd say the solution is to hit less icebergs, which is the same as eat less calories or drink less alcohol. That's a very superficial understanding. You have to get to the deeper level, which is say, why did the Titanic hit that iceberg? It was going too fast and there was all these

• 1:11:29Speaker 00

  icebergs and it's going too fast for where it was. So then you say, it needs to slow down. Now you've identified that deeper understanding, same as with calories. You can say eat less calories and for some people will work. But for some people, it's like, why are you eating so many calories? Is it because you're hungry? Why are you hungry? Is it because all those calories that you're eating are going immediately into storage? You're eating white bread and jam and sugar and all of it's going directly into storage, which is leaving you hungry, which is making you eat too many calories. So in the end, yes, you are eating more calories, but that's the sort of first order thinking and not the second order thinking that we need to be doing. And that's what the Ozempic and so on starts to address is the hunger issue.

• 1:12:12Steven Bartlett?

  And this is really what all your work addresses. And it's really the first time I've heard someone talk to me about obesity and weight gain through the lens of hormones. Never really, I've never heard that before. And reading through your work was really illuminating because it allowed me to change my frame. And as you say, when we're just focusing on the surface, it's very easy to fail because we need to understand the first principles of what's going on underneath the surface for that long-term success to stand a chance of occurring. And I think everyone listening to this who's struggled with weight or obesity or whatever else can relate to this idea that something's not working in, you know, if there was any diet that worked, there wouldn't be a thousand of them.

• 1:12:56Speaker 00

  Yeah. And I think the other thing is to understand that it's not the personal failing that we make it out to be, which is, I think, extremely unfair because obviously there's something within the system, within the food environment, within the system of how we're framing it, which is making a lot of people overweight. But it's not because they don't have willpower or because they're weak or these other number of reasons that we stigmatize obesity because we look at it from that calories in, calories out framework, right? We say, you're eating too many calories, you must be weak. As opposed to you're eating too many calories, what, why is it that you're eating too many calories?

• 1:13:41Speaker 00

  Why are you hungry all the time?

• 1:13:42Steven Bartlett?

  In a word then, if you had to describe what you think about this idea of calories in, calories out, what is that word?

• 1:13:51Speaker 00

  I would say that it's shallow. It's correct if you don't think about it too hard. Anybody who focuses in on thermodynamics and calories hasn't really thought about the problem enough. That's what I think. So in the end, it is correct, just like alcohol in, alcohol out, you know, hitting the iceberg. Yes, it did hit an iceberg. That's why, but it was going too fast, right? Or alcohol in, yes, if you drink less alcohol, you'll cure your alcoholism, but you won't cure the PTSD that caused you to drink.

• 1:14:26Steven Bartlett?

  Correct, but not helpful.

• 1:14:28Speaker 00

  Exactly. That's exactly right. It's, it's, it's, it is correct, but it's sort of not getting to that root deeper cause that we need to in order to help people. And that's causing us to blame them. So what we're doing, which I think is very unfair, is blaming the victim. Like, do you think this person who's trying to lose 50 pounds needs you to tell them they need, need to lose 50 pounds? Absolutely not. That's only going to be the 10,000th time they've heard it.

• 1:15:02Steven Bartlett?

  It's interesting because one of our guests talked about the role of compassion and kindness in weight loss. And now through the lens of understanding cortisol, now I can understand how kindness and gratitude and being happy.

• 1:15:16Speaker 00

  Yeah.

• 1:15:17Steven Bartlett?

  You know, for lack of a better word, can help us lose weight. And when we're not happy, when we're resentful, when we're low in gratitude, when we're bitter.

• 1:15:26Speaker 00

  Yeah.

• 1:15:27Steven Bartlett?

  We're more likely to gain weight.

• 1:15:29Speaker 00

  And, and, and other things help too. Because if you think about things like a sense of community, it's very important.

• 1:15:35Steven Bartlett?

  Lowers cortisol levels.

• 1:15:37Speaker 00

  Lowest cortisol is a way for you to relieve stress, right? Talking to other people. We did that, if we did, of course, limit that during COVID. And of course, we saw a lot of problems, but one of them was loneliness and all these sort of things. But again, I always think about, um, you know, people, you know, the way they are. So if you look at a lot of religions, for example, it's like, oh, they were so far ahead of us. What did they do? They brought people together every week.

• 1:16:09Speaker 00

  Oh, you're building a sense of community. Fasting, oh, they all got together and fasted. They all shared. They're lowering their cortisol. They're lowering their insulin levels. They're staying healthy. And we, in our big McMansions, right? We eat the ice cream for dinner and we live alone in this giant house. And we wonder why we're not as happy as, you know, our grandparents or our parents before them, because they understood the power of some of these things that we're trying to get back to. Like, the weirdest thing is that I'm not trying to tell people something that's weird and unusual, and you never thought about this before.

• 1:16:50Speaker 00

  I'm trying to tell them about something that everybody in human history has been exposed to, which is intermittent fasting. That's been a part of our human history, whether it's through religion or whether it's through inadvertent whatever, or whether it's through his cleansing and purifications and all this sort of stuff. People have been exposed to it, even in the English language. Breakfast, break your fast. You need to feed, then you need to fast, then you need to break your fast. So I'm not telling people anything different.

• 1:17:22Steven Bartlett?

  Jason, thank you so much. We feel like we could talk for hours because I'm so, there's so many sort of, I was thinking about it like spider webs, but there's so many little branches we could go off on as it relates to hormones and the impact of hormones on the human body. You have this other book as well called The PCOS Plan, Preventing and Reversing Polycystic Ovary Syndrome, which is a whole nother conversation for another time. But these books are so wonderful because they provide a new lens on an old conversation and a conversation that's lacked the depth that's required to make any significant progress on these subjects. As we've seen, obesity levels and other issues with weight have gone in the wrong direction for the last couple of decades. And I think it's a more systemic understanding of these issues that will give us any chance of reversing it.

• 1:18:07Steven Bartlett?

  And that's exactly what your work does. Everyone knows where to find you. Dr. Jason Fung will link all of your work in the description below. We have a closing tradition on this podcast where the last guest leaves a question for the next guest without knowing who they're leaving it for. And the question that's been left for you is, what is your greatest gift to the world?

• 1:18:31Speaker 00

  I think if, if, if, you know, I suppose it's, sounds very arrogant. But I really hope that my, my work helps people sort of reverse the type two diabetes. Cause that is really sort of one of the most close things that I deal with because I deal with it professionally sort of every day. And helps break the stigma of, not just the stigma, but the understanding like, you know, stimulates more thinking about weight loss, how to lose weight more than calories in, calories out.

• 1:19:14Speaker 00

  I mean, it's so sort of pie in the sky because you know, it's, there's a whole, you know, worldwide sort of institutionalized, fossilized almost, you know, thinking around calories. It's all about calories, sort of thing. So to, for me to upset, it seems ridiculous. But I hope that I can at least start that conversation to say, hey, let's think about these things. Let's think about the hormones. Let's think about reversing type two diabetes. Let's think about all getting together and helping each other to become so much healthier,

• 1:19:53Speaker 00

  not through drugs and not through more surgery and not with, you know, weird and new things that you've never heard of, but with the tried and the true sort of oldest thinking that has been there, right? It's, it's, to me, it's, I, I sometimes think about this and I get crazy. I like, why do I think I can even do that, right? It's just ridiculous. It's so much hubris, but you know, I, I can only try, right? Because I, I see in my own practice, how much good it's done for some people. So it drives me to say, I need to bring it to more people. I need to, to, to explain it to them. If they want to be helped, they will be helped. But if they don't want to understand this, okay, I'm not trying to force myself to do anything.

• 1:20:38Speaker 00

  But you know, that's what I hope my greatest gift will be. But at the same time, I sort of think. That's just, you know, you're crazy if you can think you can do that, but.

• 1:20:50Steven Bartlett?

  Well, it's the crazy ones that change the world, Dr. Jason. It's the crazy ones that change the world. And even with, you know, your conversation around intermittent fasting has changed many, many lives that you'll never get to meet. I imagine many, many millions, many, many millions, because it's even brought the conversation to this show before you entered the room many, many months and months and months. And almost a year ago, people started talking on the show about intermittent fasting. And that's in many respects, due to the work that you've done to further that conversation. And now your work continues to highlight the fact that type 2 diabetes is a reversible disease in many cases. And I think, again, that's going to save, you know, tens of millions, if not hundreds of millions of lives over the coming, coming decades and years. So

• 1:21:34Steven Bartlett?

  thank you for what you do, Dr. Jason. It's a huge honour to get to sit with you today. And I feel wiser and more enlightened and like someone has turned the lights on in a certain part of my knowledge because of this conversation. So I thank you for that tremendously.

• 1:21:47Speaker 00

  Thank you so much. It's been great.

• 1:21:51Steven Bartlett?

  Do you need a podcast to listen to next? We've discovered that people who liked this episode also tend to absolutely love another recent episode we've done. So I've linked that episode in the description below. I know you'll enjoy it.