Transcript

Most Replayed Moment: Calories In, Calories Out Is A Myth! Why Most Diets Fail - Dr. Jason Fung

0:00 Uh Ch 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 calorie in, calorie out. Are independent of each other, so won't trigger one another.

0:16 Um this interesting point about the basal metabolic rate. being stable. Yeah. Is that in essence because people you know, p people will often say I have a low Metabolism. It's kind of like a word and culture. Someone is um A beast often the

0:30 The diagnosis is they have a low metabolism. Yeah. Is there any merit in that? Is that true? 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 five hundred fewer calories and you'll lose a pound of fat per week. It's It's unquestionably false. Because every single study that we've done over the last fifty years

0:58 shows that if you eat five hundred fewer calories, Then Over time, depending on what foods you're eating, eventually your body will just burn five hundred 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. We've known about it for like eighty years at least.

1:20 You eat fewer calories. Your body burns fewer calories. Well, that's going to limit how much weight you're gonna 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 five hundred less, your body but burns five hundred less.

1:45 And you're not losing any body weight. I go on a diet, let's say. 'cause I'm trying to lose weight. My metabolism lowers to meet the colorific restriction that I've imposed on myself. Yeah.

1:58 What then happens when I come off the diet? Does my metabolism stay? Generally yes. So that's that yo yo dieting effect. So say you start with two thousand calories in. two thousand calories out. You're not gaining weight, you're not losing weight, right? Now you decide, okay, I'm gonna go on a diet. So you go down to fifteen hundred calories, thinking that you're gonna burn two thousand.

2:21 And the body fat's gonna provide five hundred, 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 ten 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.

2:41 Okay, so we've again we've known about this for eighty years. So now you eat fifteen hundred calories, but you're keeping your insulin levels really high. So fewer calories. But Lots of high carb foods, eating all the time. Insulin stays high. You're you're taking in fifteen hundred.

2:57 But you can't burn any body fat. So the calories that are stored in your body fat cannot be m cannot be sort of taken out. It's like it's in the bank and the bank is closed. It's it you can't take it out. So what's going to happen? Well, you don't have a balanced equation.

3:14 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 fifteen hundred calories coming in. Your body can only burn fifteen hundred calories. Your metabolic rate has just now gone down by five hundred calories. And guess what? You're not losing any Body fat.

3:33 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 eighteen hundred calories.

3:55 So now you're eating 1800 calories, but you're only burning 1500 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 two thousand calories you used to eat. You're eating eighteen hundred, but you're eating the wrong foods. You're very high insulin foods.

4:13 So therefore you're going to gain weight. In fact, everybody says that. And and all the all the nutritionists, all the doctors just they just don't believe'em. They say you're lying, you're cheating, you're eating more than you think. 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

4:34 Post about it online as well. Um 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's this guy eating all these pizzas, but he's using this calories in, calorie out thing?

4:52 And then when the pizza stopped Yeah. There was this yo yo effect. Yeah. Where He managed to get to basically what I describe as a six pack or thereabouts. And then um Stopped eating all s uh stopped the diet per se. And then there was this big yo yo effect.

5:08 Which I imagine is what you said there. What he's done is he's lowered his metabolism. And when he goes up just a little bit. It all comes back. It all comes back and then some. And then some. Yeah, absolutely. So this form of dieting is actually over the long term probably gonna make you gain weight. Oh, it's 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.

5:35 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 two thousand calories in, two thousand calories out. Now you go on a diet. You want to you take in fifteen hundred. 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.

6:03 Right. So when you eat, instinct goes up, your body wants to store energy. When you don't eat, anything 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 fifteen hundred calories, but you do intermittent fasting. So you're allowing your insulin levels to fall. Now fifteen hundred calories are coming in.

6:22 Insulin levels are low. Your body wants to burn two thousand calories. It says, well, insulin levels are low. Let me take 500 calories from my body fat. Guess what? You have five hundred coming for your body fat, you have fifteen hundred coming from your foods, you burn two thousand. It's a balanced equation.

6:40 So instead of the opposite situation, so and and you see that the calories are the same. You went from two thousand in to fifteen hundred in. But what the difference was that 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

7:00 Body fat can come out. And this is the piece that's missing because people are all 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? Because there's two hundred, three hundred thousand 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.

7:20 So now if you do intermittent fasting, you eat fifteen hundred calories, you take five hundred calories out, your body's burning two thousand. Now all of a sudden if you go off your diet and you go back to two thousand calories, Guess what? You don't gain weight, you don't lose weight. Same as before. Whereas before you go even to eighteen hundred calories. You lost weight.

7:39 But the difference was not the calories. It was always two thousand to five hundred. 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 the there's there's cortisol is a is a very important hormone. There's other hormones. You mentioned burning calories there. One of the thoughts around the calories in, calories out model is that you can just exercise

8:07 And if you burn a thousand calories exercising, then that gives you a little bit of a reserve there to eat more, for example. Yeah, and it's probably a very, very small effect for for a couple of reasons. So we know that uh if you exercise And I and I say this, uh exercise Is really good for you in a number of ways. Flexibility, strength.

8:31 core, all kinds of things. So very, very important. But in terms of weight loss It's actually a 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 gonna 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 on very, very slowly, right? You'll do half an hour and it'll be

9:13 Up to like a hundred and twenty calories or something like that, right? 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,

9:41 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 uh again, we've had decades of study for this. If you exercise, during the exercise you have uh loss uh uh reduced appetite.

10:00 So you have exer 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 air, you know, in your muscles and so on. uh 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 gonna 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 uh for for children um in

10:39 certain activity. So they said, okay, what if the child is watching TV? What's the average uh caloric difference. And it was like plus one hundred calories per hour. So for every hour of TV their sort of positive one hundred 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 one hundred calories. So The only way that happens is that if that exercise

11:05 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. You say in the book in chapter four that ninety five percent of weight loss is diet Yeah. And that's the reason why

11:25 Exercise it's very hard to exercise enough. to lose weight. And 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 Yes. Still gotta focus on the main

11:43 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. An American survey of more than sixty thousand adults and children revealed that in nineteen seventy seven most people ate three times a day. By two thousand and three, most people were eating five to six times a day. Yeah. Yeah, this is the whole idea of sort of

12:21 Eating all the time. I find fascinating because it was this sort of inadvertent change in our diet that we never talked about, right? So in nineteen seventy seven, we told people eat lots of carbs. Okay. So we know that. That's in print. For sure, the American government said eat fifty five to sixty percent carbs eat less fat. What happened is that, you know, in nineteen seventy seven people ate breakfast, lunch, and dinner.

12:49 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 ate more at dinner, right? No problem. But what happened is that as we started to eat

13:03 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. Because you're hungry again. Then you get hungry at ten thirty. So you go around looking for a low fat muffin. And it was because you know, uh 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 three 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 two thousand and three is eating six, five, six times a day.

13:50 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 the snacking becomes institutionalized, whereas pre-neteen seventy seven snacks are an indulgence. Right? It's not something good for you.

14:04 It's something bad for you, but once in a while you 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 gonna go up, your body's going to store calories because you're told it to. If you don't eat or if you fast,

14:29 Your body is your your insulin's gonna go down, you're going to bring those calories back out of storage. Right? So you're gonna 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.

14:45 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 gonna allow fat burning. Which is gonna allow you to pull those calories back out. You're cited as being a 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.

15:18 But The internet says that it really came from you. I know that interesting fasting's been happening for thousands of years, but The idea of it as a tool for weight loss. They say it came from you. Because in twenty thirteen, twenty fourteen, 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

15:44 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 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 gonna 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 two thousand years 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 uh sort of public consciousness that this is a tool. That's all it is. Oh, absolutely. Like

16:31 I got. I got attacked from all sides. I got you know doctors were coming after me, dietitians were coming after me, everybody thought I was gonna do so much harm. And the funny part was that You know, as I think back, uh as I spoke to a lot of colleagues, a lot of colleagues would say to me

16:48 You know what? I used to do that when I was in training. We did that all the time. We'd go twenty four hours without eating because we're in the OR, or we're in the ER, or we're 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.

17:05 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. So why is it that I'm actually telling people to fast? All the time.

17:18 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. Uh one of the things people talked about was You know, it's gonna make you eat more later. It's gonna make you more hungry, your basal metabolic rate's gonna go down. This was one of the big myths of intermittent fasting. That's gonna 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 gonna gain weight again.

17:46 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 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.

18:05 So On day zero, they say you're you're burning, say, two thousand calories a day. On day four of zero food, you don't eat f any food for four days, they measure how much calories you're burning, your body is burning twenty two hundred calories. Your basal metabolic rate didn't go down. It went up. Your body's activating itself during fasting.

18:26 Which is fascinating because if you're trying to lose weight. Dropping that metal metabolic rate is death. Like If you drop that metabolic range It's so hard to lose weight.

18:37 That's what the calorie restricted diets did. 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?

19:00 Is that your insulin's gonna fall? you're gonna 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.

19:15 your cortisol levels go up because again it's an activation and your growth hormone goes up. Because those hormones are gonna start telling your body to start pulling calories out. So you're actually activating yourself. Think about in the wild, if you see a hungry wolf, is that wolf just sort of uh you know, all like lethargic? No, he's activated. He's actually more dangerous than any other wolf.

19:39 As opposed to say a lion who just ate. Because when you just eat, you just wanna lie there. You know, you you wanna digest your food. You have no energy. So people say, Well, your your your metabolic rate's gonna go down if you fast. No. The the truth is actually the opposite. It goes up. an instruction I'm giving my body because if I eat this food, it's gonna have this impact on my hormones, which is gonna 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

20:08 eating and a little bit about fasting. I wanna get into that a little bit more. But Breakfast. I read that you didn't Think most people need breakfast. Yeah, the the whole idea that you need to eat as soon as you get up.

20:21 Is just false. So there's this whole um 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.

20:40 Every day. Why? There's a period of time that you're supposed to feed. You eat? instant goes up, you store calories. Then there's supposed to be a period of time that you fast.

20:50 That's after dinner. until the next day's meal, which is breakfast, right? So you say you stop eating at six PM, you eat at eight AM, that's a fourteen hour period. Where your body is not eating, it's fasting. And therefore it's gonna 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.

21:17 Your body's just gonna store energy and never have a period To burn energy. So Okay, well, what's gonna happen? You're gonna gain weight. What you just listened to was a most replayed moment from a previous episode. If you want to listen to that full episode, I've linked it down below. Check the description. Thank you.

21:36 Uh