Why Am I Always Hungy? | Jason Fung MD

What if the real lever for lasting weight loss isn’t calories, but hunger itself? We sit down with Dr. Jason Fung to unpack why willpower-based diets fail and how hormones like insulin, cortisol, GLP-1, and sympathetic tone quietly set your “fat thermostat.” Instead of fighting biology, we explore how to work with it—lowering insulin, raising satiety, and removing the triggers that keep appetite stuck in overdrive.

We dig into the three types of hunger that shape daily choices: homeostatic (physiological signals like ghrelin and leptin), hedonic (reward and emotion), and conditioned (learned cues from cars, screens, and social settings). Jason explains how ultra-processed foods exploit these systems by maximizing pleasure and minimizing fullness, why sleep and stress can spike cravings through cortisol, and how fasting strategically restores access to stored energy. We also discuss the difference between visceral and subcutaneous fat, why some people appear “skinny fat,” and how testing insulin, A1C, and C‑peptide gives a truer metabolic picture than BMI alone.

From the failures of low-fat, calorie-counting eras to the surprising benefits seen with GLP-1 agonists, the throughline is clear: control hunger, and calories take care of themselves. You’ll leave with three golden rules to start today—ditch ultra-processed foods, use fasting windows to lower insulin, and build a supportive circle that normalizes real food. It’s a humane, science-driven framework that helps you stop battling your body and start resetting your internal settings.

If this conversation helped reframe your approach to weight and health, follow the show, share it with a friend, and leave a quick review to help others find it.

https://www.doctorjasonfung.com/

Continue this conversation on SubStack: https://robertlufkinmd.substack.com 

Lies I Taught In Medical School : Free sample chapter- https://www.robertlufkinmd.com/lies/

Web: https://robertlufkinmd.com/
X: https://x.com/robertlufkinmd
Youtube: https://www.youtube.com/robertLufkinmd
Instagram: https://www.instagram.com/robertlufkinmd/
LinkedIn: https://www.linkedin.com/in/robertlufkinmd/
TikTok: https://www.tiktok.com/@robertlufkin
Threads: https://www.threads.net/@robertlufkinmd
Facebook: https://www.facebook.com/robertlufkinmd
Bluesky: https://bsky.app/profile/robertlufkinmd.bsky.social
Mastodon: ...

Transcript

Meet Dr. Jason Fung

SPEAKER_00 0:01

Hey Jason, welcome to the program. Hey, good to see you, Robert. My brother, it's great to see you. I I I've been a huge, a huge fan of yours, like so many people for so long. You were kind enough to write the foreword to our book that we did. And now you have an amazing book that's going to be coming out about uh the week of this podcast uh called The Hunger Code. And we're gonna dive into that. I can't wait to talk about that. Um but before we do, since it's the first time you've been on this podcast, uh maybe you could just take a take a few moments and uh talk about your journey and maybe what what made you decide to write this book?

From Kidneys To Obesity Science

Beyond Calories: Metabolic Rate And Hormones

Insulin’s Role In Weight Gain

Fasting Physiology And Benefits

SPEAKER_01 0:49

Yeah, so uh I'm a nephrologist, so I'm a kidney specialist, and I um have been one for like 25 years. I did my training in Los Angeles at Cedar Sinai Hospital. And um after that, I started taking care of kidney patients. And the majority of my patients were type 2 diabetes. And as it went on, because I graduated in 2001, uh, there was more and more diabetes. There's basically a large epidemic of type 2 diabetes, which led to a large epidemic of diabetic kidney disease. So uh around 2012, 2013, I started really getting interested in the question of weight loss. And the reason was very simple. Um, type 2 diabetes causes the kidney disease. So, if you really want to do something about reducing kidney disease, you have to get rid of the type 2 diabetes, which of course everybody at the time was saying was impossible. It's a chronic and progressive disease. There's no remission. The criteria for remission didn't come in until like 2023 or something crazy stupid like that. But it was clear at the time to anybody who would pay attention that type 2 diabetes was reversible. Because if you lost weight, everybody knew that your type 2 diabetes would either get better or go away. So the question wasn't uh, you know, was it reversible? It was definitely reversible. It was just a matter of getting people to lose weight. So I became very, very interested in the question of weight loss. And of course, I hadn't thought about it too much because you know, in medical school, they just tell you calories in, calories out, right? And that was sort of it. That was the limit of the thinking. And as I really started to think about the problem of weight loss, it was clear that that was not true at all, right? Because the the the normal thinking was calories in minus calories out equals increased body fat. Now that is always true, but it actually doesn't mean what people think it means. People think it means if you eat fewer calories, you're going to lose body fat. But that's not what it means at all. If you lose, if you eat fewer calories, you could just as easily burn fewer calories and you still won't lose that body fat. And the thing is that people thought that burning the calorie expenditure was just a matter of uh exercise, but really it's not. It's mostly metabolic rate. And everybody knew this, of course. It's the energy your brain and your heart and your lungs and your kidneys need to sort of keep going. So that's where I really got interested in the whole topic. And the thinking was, you know, it's all about calories in. So if you just reduce your calories and if you couldn't lose weight, you just had no willpower. But that didn't make sense at all. Because at the same time, we knew there's lots of drugs that cause weight gain. So insulin. If you give somebody insulin, they gain weight. If you give somebody prednisone, which is a synthetic form of cortisol, they gain weight. If you gave somebody a beta blocker, they gain weight. If you gave them an antipsychotic, they gain weight. It had nothing to do with their willpower. They had the same amount of willpower that they had before you gave them the insulin. It was the insulin, obviously, that made them gain weight. So therefore, it was really, you know, a step back to say, okay, what's happening here? Because it's really the um insulin that's causing the weight gain, right? And that makes sense because insulin is a hormone whose job it is to tell you to store energy in the form of calories, right? When insulin goes up, you're you're gonna store calories because that's what its job is to do. So if your insulin levels are too high, then you're gonna store too much body fat. And you're going to do it by causing the calories in to be greater than the calories out. Either you're gonna be hungry and eat more, or if you eat the same, your your metabolic rate will just go down. So that's where the obesity code I started to write about, you know, weight loss, weight gain, about insulin, about the role of hormones in uh in uh body fat percentage, which of course, everything in our body runs on hormones. So why would we expect body fat and storage of calories to be any different, right? There are hormones that you know make you store body fat, there are hormones that make you release body fat, there are hormones that make you hungry, there are hormones that make you full. So, why is it all about willpower? Like, how is that physiologic? So, this whole idea of calories actually is not based in human physiology, sort of at all. It's a it's a notion out of physics, really. This sort of energy balance equation is about physics, not human physiology, because the human body doesn't run like that. And so that's where I wrote the obesity code. And then I also talked about diabetes and the diabetes code, which was again a real sort of rethinking of the way we treated diabetes, which was focusing on the insulin part of the story, because again, everybody focused on the sugar, but the problem, the blood sugar, but the problem was actually the high insulin that's causing all the issues. So, again, if you don't eat, such as fasting, or if you reduce your carbohydrates by lowering which lowers your insulin release, you're gonna do better. So that was that was where that all started. And so the the fasting was one of these things, again, I started to think about the insulin and how are you gonna get the insulin down, right? If insulin is too high, because that's what's causing weight gain, then how do you get the insulin down? Well, obviously, you could simply not eat, which is fasting. And at the time, people thought it was the worst thing in the world. It is so unhealthy for you. You shouldn't ever fast. And I was like, why not? Why couldn't you fast? Like, seriously, let's look at the physiology behind it. And there's nothing wrong with it. Your body stores calories. When you fast, you burn those calories that you've stored, right? So if you have too much body, if you have too much sugar and your blood sugars are high and you have type 2 diabetes, you're gonna burn that sugar. That's normal. If you have too much body fat, which again is just a store of calories, why don't you not eat so you can burn those calories, right? It to me, it seemed like an obvious solution. So that's where I started writing about it and and talking about the the why fasting is really not bad for you, and you know, it can be done and can be actually, and it turned out it had some really, really interesting properties, such as autophagy, um, you know, this idea of rejuvenation of a lot of the cells and subcellular structures, anti-inflammation, even maybe an anti-cancer role, sort of dementia, you know, all of these hidden benefits that come with perhaps the fasting and some of the longer fasts that people do. So that's that's where it came from. And then the hunger code is actually a follow-up to the obesity code. Uh, so again, talking about the obesity code talked about the sort of hormonal uh impact of uh you know how we gain and lose weight, and the hunger code is really the next step, which is looking at sort of more the more of those hormones. So the obesity code dealt with cortisol and insulin, and this deals with GLP, GIP, sympathetic tone, baroreceptors, and it really covers the topic of why we eat, right? So if you think about you know the the idea of why we overeat, well, why do we eat? Uh, you eat because you're hungry, right? So the question is, why are you hungry, right? And there's a whole hormonal part of things, which is the homeostatic hunger. So this is the insulin, the cortisol, all the gorillin, leptin, all of those hormones that deal with hunger. But it turns out there's much more than the physical hunger, there's a whole emotional hunger, which is called hedonic hunger. And that is you eat because it can make you feel good. It tastes good, it looks good, you want to, even though you're not physically hungry. And so if you think about dessert, nobody eats dessert because they're hungry. You eat because it looks good and it tastes good and you want to, right? So why would you deny that that's a real problem? And in some cases, especially with ultra-processed foods and food addiction, that hedonic hunger just gets turned around. And a lot of these ultra-processed foods create a lot of hunger that make you overeat. And then there's also conditioned hunger, which is the stimulus, which is um, you know, if you get into the habit of eating. So you get in the habit of eating at meetings in the car in front of the TV. But what's going to happen is that every time you sit in front of the TV, you're going to want to eat. Every time you go in the car, you're going to want to eat. Every time you see, you know, uh a movie, you're going to want to eat. So it's this sort of social conditioning, which is actually very important: social modeling, social influence, and conditioning, which again creates that hunger that makes us overeat. So it's getting to that sort of deeper understanding of what drives our eating behavior. And it's the three types of hunger: homeostatic, hedonic, and conditioned, which you can sort of think of as physical hunger, emotional hunger, and social hunger, which are very important. And I think that people just don't talk about it enough. And I think that the issue is that if you think about uh losing weight and you think it's just about the food, you sort of already lost because it's about eating behaviors. It's about mindsets, it's about your friends, it's about your social supports, it's about accountabilities, it's about habits, it's about all of those things rather than just the food. We all know what food we're gonna eat. I mean, I know I probably shouldn't eat brownies. Doesn't mean I won't eat brownies, right? Why? Because again, it could be conditioned hunger. Maybe I'm used to eating brownies at Christmas because my aunt always brings them. Or it could be hedonic hunger. I'm feeling down. I want to eat that brownie so I feel better, right? But you have to understand why you're doing what you're doing, which is that that sort of deeper uh puzzle.

SPEAKER_00 10:54

Yeah, this this book is certainly timely. And you know, in the in the United States, and I think Canada is not not far behind. We in the last 30 to 40 years, we've seen a explosion in obesity and overweight people to where in the US most adults today are overweight or obese. And this this uh situation, this this condition drives many other metabolic conditions we can talk about. But maybe, maybe could you just kind of a basic level one of the one of the great concepts in in this book, I I think is really valuable is the body fat thermostat. So can you walk us through how you know insulin, leptin, ghrelin, glp1s, gifs interact to create this this thermostat? It really was a light bulb moment for me, and it helps it helps a lot of people, I think, understand that it's not just calories in, calories out.

Three Types Of Hunger

The Body Fat Thermostat Explained

GLP1, Sympathetic Tone, And Appetite

SPEAKER_01 11:50

Yeah, that's such a simplistic notion. So getting to the calories in, calories out. First of all, you have to understand that that's a very sort of it's a first-order thinking sort of uh thing. So calories in, calories out, you know, the reason people sort of obsess about it is because they say body fat equals calories in minus calories out. And that's always true. But the problem is that that's not actually useful because you have to get into the deeper reason. Uh and there's a concept in logic called the three whys. So the three whys says that if you, you know, answer the question at a superficial level, you won't actually get useful advice. You have to ask the question why, sort of three times. So if you're to say, why did the Titanic sink? You might say, because it hit an iceberg. And technically it's true, but it's not useful knowledge, right? Because if you're trying to prevent future disasters, what would you tell future captains? Would you say, don't hit icebergs? It's like, sure, it's not that useful. So then what's the correct answer? Because it hit an iceberg is not the correct answer because it's too superficial, right? It doesn't get to the root problem. So then you have to ask the question, uh, why three times. So that's the first why. The second why would be say, why did it hit an iceberg? Right. And then you'd say, well, the captain couldn't avoid it. Then the third why would be say, why couldn't the captain avoid this iceberg? And the answer is because it was going too fast. Now, by the time you get to that third why, now you've got an answer. Now you can say to future captains, you need to slow down, right? It's just like if you're driving on an icy road and you fly off the road, right? Why did you fly off the road? It's like, because you know, the the force pushing me off was greater than the force keeping me on, right? And it's like, why? Because you hit black ice. Why? Because you're going too fast, right? So slow down, right? So the answer to the question is to slow down, not don't hit icebergs. And see, the calories in, calories out is the same level of superficial knowledge that people are sort of always aggressively defending. It's like, why did you gain body fat? Because the calories in is greater than the calories out. Okay, true. Now it's not useful. That's the don't hit icebergs type of advice, right? So what we tell people eat fewer calories is the don't hit icebergs advice. Not useful. You have to say, why is calories in greater than calories out? Because you're hungry. That's the reason that calories in is greater than calories out, right? And then then you get to the third why, which is why are you hungry? Which gets you to the homeostatic hunger, the hedonic hunger, and the conditioned hunger. Now you've got something to focus on. And this homeostatic hunger is a core principle of the human body. Okay. So homeostasis is basically where the body needs to maintain a sort of normal condition. So if you're living in the Sahara Desert and it's really hot, you're going to sweat, which brings your body temperature back down. If you live at the North Pole and it's very cold, you're going to shiver and your body temperature goes up. Either way, no matter what is happening outside, you try to maintain that normal homeostatic, right? It's a normal homeostatic mechanism. If you drink a lot of water, you're going to pee it out. If you don't drink a lot of water, you're not going to pee it out. If you eat a lot of sodium, you'll pee out the sodium. If you don't eat a lot of sodium, you won't. So the body always adjusts, right? It always maintains this. And body fat percentage is the same thing. There are people that say, oh, well, we're, you know, if you eat more than you burn, then you're going to throw these calories into body fat the same way you'd throw, you know, doorknobs into a sack, right? It's like, oh, here, without any knowledge or thought. Well, why would the human body not control the body fat percentage? Because it's absolutely critical to maintain the proper body fat percentage. In the wild, you never see morbidly obese animals. You don't see morbidly obese lions or deer or tigers, right? And it's because if you're a predator and you're morbidly obese, you will not catch any prey and you're going to starve, and then that'll correct the problem. If you're a morbidly obese deer, you're going to get eaten, you're going to die. So either way, too much body fat is bad. Too little body fat, the minute you hit winter and can't eat anything, you're going to die. So too little body fat is also bad. But either way, your body sets that homeostatic mechanism to maintain a certain range. That's why in the wild you don't see morbidly obese animals. As you point out, except now in dogs and stuff, dogs and cats, when you feed them human food, then they get problems, right? When you change the food supply. But the same thing in antiquity. You might have a period of time, you know, in the Joseph story of Joseph, for example, they had seven years of plenty. They didn't talk about an ancient plague of morbid obesity. That didn't happen, right? Because your body maintains that same body weight. So therefore, it's like a thermostat, right? It's a homeostatic mechanism that maintains your body fat at a certain percentage. So if your body fat is too high, then you have to say, why is that body fat thermostat adjusted higher, right? Just like if you were to go into a room and it's too hot. You don't say, why is heat in greater than heat out, right? You say, who turned up the thermostat? Right? That's what you'd say. Same thing here. Why has that body fat thermostat adjusted upwards? What pushes it up? What pushes it down? And it's hormones. So insulin, for example, pushes it up. How do we know that? I could I can make anybody fat. I give them insulin. I can make you fat. If I gave you enough insulin, you'd get fat. There'd be nothing you can do about it because the instructions I gave to your body would be to get fat. Or I give you prednisone, which is like cortisol, the stress hormone. You'd get fat. There's nothing you can do about it. I don't care if you have all the willpower in the world, you'd still get fat. Because I told you that is the cortisol is pushing that body fat thermostat up. Therefore, then you have to look and say, okay, it's getting pushed up. Insulin is pushing my body fat thermostat up. How is it making me fat? It's causing you to be hungry, right? Or if you don't eat anymore because you you're you're turning on your willpower, then it's going to reduce your energy expenditure. Either way, you're still going to gain fat, right? And that's the key. The hunger is the the way the the effector mechanism of this body fat thermostat. Just like your thermostat doesn't heat the room, the thermostat turns on the air conditioning or the heater, right? The the body fat thermostat turns on mechanisms like hunger and satiety and metabolic rate to adjust your weight up and down. So those push it up. What pushes it down? Lots of things. GLP1. We know we stimulate GLP1. And I always think this is strange because lots of people always rag on me about oh, it's not about insulin. I'm like, you know, GLP1, which is Ozempic, you know, it stimulates Ozempic, is GLP1 is glucagon-like peptide, right? Glucagon is basically the opposite hormone of insulin. So what happens when you stimulate the opposite of insulin? You lose weight. So tell me that insulin isn't important, right? Obviously, when you're stimulating insulin, you gain weight. When you stimulate glucagon, which is, you know, uh the opposite of insulin, you'll lose weight. So tell me that that's not an important hormonal pathway, right? And the key is that these hormones don't have calories, right? When you stimulate GLP1, there's no calories. You take Ozempic, there's no calories in GLP1. Ozempic does not restrict your calories, it restricts Your hunger, right? It pushes that body fat thermostat down, which kills your hunger, and then you don't want to eat, and then you lose weight, right? But the root cause was the GLP1, was the hormonal status. So if you think about push what pushes it up, what pushes it down, it's a huge range. It's not just insulin, cortisol, GLP1, GIP, glucagon, because now there's glucagon inhibitors as well, right? But also things like sympathetic tone. So if you increase sympathetic tone, you're going to lose weight. How do you know this? Well, all those old drugs, those um weight loss drugs, I don't know if you remember uh fenfen, but fenfense this classic cautionary tale of uh fenfluoramine, fenteramine. And basically, it caused a lot of weight loss, like 17 to 20 percent of body weight. So on par with Ozempic. The re the problem is it caused heart valve problems, and so they that that got discontinued, but it was actually a very effective drug. How did it work? It pushed up your sympathetic tone, your hunger died, and you didn't want to eat. And in fact, these drugs were classified as anorexians. That was the class of drugs that they were called, anorexians. If they they worked by killing your appetite, that is inducing anorexia, right? Anorexia is a medical term for loss of appetite. So the whole point is that if you increase sympathetic tone, whether it's phenfluoramine or whether it's nicotine or whether it's these uh some um sympathomemics like um uh speed, you know, uh crack, you know, all of those, what do crackheads look like? They're skinny as a rail. Smokers, they they they are skinnier than non-smokers. That's actually just a very well-documented fact. So again, it's not because it changes your calories, it changes your hunger because it pushes that up and down. So sympathetic tone, very important. You block it through beta blockers, you gain weight, right? Um, dopamine system, for example. So if you, you know, we know that uh it food has a rewarding effect. So dopamine, um, antipsychotics and antidepressants have a weight gain effect, right? When you start blocking serotonin and all these other uh things. So we know from all of these drugs, from all of our studies, that these adjusted up and down. That's how you get weight gain, weight loss. So baroreceptors in the stomach. So when your stomach is filled up, you activate stretch receptors in the stomach, which signal your brain to stop eating. So if you're eating a lot of very bulky foods, you're gonna stretch your stomach and it's gonna signal, right? So there's a whole uh diet that used to be called volumetrics, where you you you ate very bulky food and it could work, right? Um, that's the medical condition called the bezoar. So a bezoar, where your hair, uh hair fills your stomach, people lose weight, not because they can't digest the food. You can still drink sodas and stuff and get all the calories you want. The problem is that your hunger just went down because of those barrel receptors. So there's all these things that are important in weight loss, which is the homeostatic hunger. Sleep is another classic example. We all know that sleeping, if you don't get enough sleep, you're gonna gain weight. Again, fairly well documented. Um, but lack of sleep doesn't have calories. So why would you gain weight? All those calories in, calories out people are just like, because I don't know, because, right? It's like, well, it's obvious if you stop, think about it. The lack of sleep is gonna raise your cortisol, which is going to increase your body fat thermostat, which is gonna make you hungry. So, what do you get in the middle of the night? You get the munchies, you want to go eat something. But the reason that you're you're you're wanting to eat something is because of the increased stress hormone and all that. So that's the homeostasis, that's the body fat thermostat. And you have to understand what are the hormones that push it up, what are the hormones that push it down? Because for one person, it'll be completely different. And I always, everybody, it always strikes me as crazy. People, these calories in, calories out people, they're always like, well, in the end, it's all down to calories. It's like, okay, you have no idea what you're talking about. Because look, if you have hunger and you have calories and you're pushing down calories, but you've completely ignored the hormonal status, what happens? Hunger goes up. So calories is down, hunger is up. You're always fighting with yourself. You're always fighting with your body. What if, on the other hand, you understood what caused hunger and satiety and you pushed down hunger, lycosempic, right? It's like the drug. You push down hunger, calories also go down. But notice you're no longer fighting with yourself. And what happens? You lose weight and you keep it off. Or fenfen, right? You push down the hunger with these uh fenteramine, um, fenfluoramine, and hunger goes down, calories go down, but you're now you're you're working together to lose weight. Nicotine, same thing. You're pushing it down, pushing it down. Oh, you can maintain that weight loss for years. If you don't, if you do this, where your hunger goes up, your calories goes down, and you're always fighting with yourself, what are you gonna do? Right? You always fail, you always fail. And that's what always strikes me is that the calories in cut your calories, which is the standard advice that you and I both learned in medical school, right? It has a horrible success rate. Uh in the book, in the hunger code, I I said there's there's been statistics, all kinds of statistics, but the actual success rate of um you know cutting your calories to lose weight in the long term is abysmal. It's about a 99.7% failure rate, right? 0.3% success rate. It's unbelievably bad. Like, why would our standard advice, which people say is, oh, it's very scientific, it's actually very simplistic. It's technically correct, but simplistic. But people insist that that's the right advice. It's like everybody knows it fails. That's why doctors like you and I stopped giving weight loss advice because what we were taught and that we told other people, just cut 500 calories a day, didn't actually work, right? So in the in when I started, I'd be like, oh, cut 500 calories a day. I'd tell patients this. It didn't work for anybody. It didn't work for me, right? Nobody. It didn't work for anybody. And understand this, you were expected to fail, right? That was the norm. That's why nobody even bothered anymore because the traditional weight loss advice was just so incredibly bad, which was cut 500 calories a day, you're gonna lose a pound a week. It was all wrong. It was actually completely wrong.

SPEAKER_00 27:02

So, so hormones are are key, obviously, and insulin is top, you know, top of the list. Um, so from a longevity perspective, what's more damaging over the decades? Chronic hyperinsulinemia or excess body fat itself? Or do they go hand in hand?

SPEAKER_01 27:18

Is it yeah, I think they go hand in hand because we know that obesity is a state of chronic insulin excess, right? So if you look at obesity, their insulin levels are generally high. Then you get to prediabetes where it's higher. And the thing is that when you start to push down your insulin levels, and again, we now have data from Ozempic, and you know, the ultimate lesson that we should learn for an Ozempic is that it's not the calories that you needed to control. It was the hunger you needed to control, right? That's the key. Now you we have a condition, we have a we have a situation where we can, you know, give somebody a drug and kill their hunger and their insulin is going to go down because they're gonna eat a lot less, right? We're pushing up the sort of glucagon part, which is the opposite of insulin. And so hunger goes down. And what happens? There's benefits that we never dreamed of, right? Oh, heart failure is better, kidney disease is better, arthritis is better, this is better, that is better. Why? Because the chronic hyperinsulinemia was so bad for us. But that's our baseline now, right? That's our baseline. So when you get rid of that chronic hyperinsulinemia, all of a sudden you're seeing benefits that you never expected that are popping out of the woodwork.

SPEAKER_00 28:31

Yeah, and and I mean, hyperinsulinemia is it's why why isn't it? Why don't more physicians check fasting insulins?

SPEAKER_01 28:41

Uh, it's the way it's taught. Again, if so, what people think uh is insulin resistance. So we get taught that there's this thing called insulin resistance, right? And so insulin resistance is this sort of boogeyman. And we all know that it's really bad for us, that is very prevalent, and it contributes to a lot of chronic disease, heart disease, kidney disease, all kinds of disease, metabolic disease. So you say, okay, we have insulin resistance. And what is insulin resistance? Well, insulin normally lets glucose into the cell. And if you have insulin but it's not going to the cell, that's called insulin resistance. But you ask somebody what causes insulin resistance, they'll be like, I don't know. The the thing is that it's actually hyperinsulinemia. So we know insulin resistance and too much insulin on the outside go hand in hand. They're actually the same thing. Because if you think about what hyper what insulin resistance is, is imagine the cell, you know, you can take a certain amount of glucose. Uh, insulin is going to let more glucose in. So if you have, for example, a a bar, you know, a restaurant, and it's Super Bowl Sunday and the bar is packed, right? And you open the door, but the bar is packed. You can't go in, right? So there's nothing wrong with the door. The problem is that the bar is full. Same thing with the cell. It can let a certain amount of glucose into that cell. But once you have chronic insulinemia, hyperinsulinemia, the the insulin's letting all the glucose into the cell, just like the restaurant's letting all the people in, that cell is full. Now the door is open and you still can't put it in. That's insulin resistance. So it's the same thing as hyperinsulinemia, right? But the problem is that when you call it hyperinsulinemia, you will know what to do. Insulin levels are too high. How do we lower insulin levels? If you call it insulin resistance, the solution's not that obvious, right? You say, I don't know what we're supposed to do about the insulin resistance. It's like just call it by what it is hyperinsulinemia. You have too much insulin. How do you lower insulin? Well, you can do fasting and you can do low-carb diets. You can also follow, you can also use drugs such as SGLT2s or GLP1s. And guess what? Those drugs have benefits nobody ever dreamed of. Heart disease, heart failure, you know, kidney disease. Again, same thing. All those drugs that the new drugs that now lower insulin are showing all these end organ benefits. It's because the insulin was actually really bad for us. But people didn't understand that because they called it by a different name. They called it insulin resistance instead of hyperinsulinemia, which is actually what the problem was. So that's why I always try and call it hyperinsulinemia. So then you say, hmm, that's easy to understand. It's sort of like if you call something hypertension, your blood pressure is too high. All right, great. How do I lower it? Or you call it hyperthyroidism. Okay, great. How do I lower it? Right. If you now call it hyperinsulinemia, oh yeah, great. How do I lower it? That's the answer. That's how you do it, right? It's low-carb diets, fasting. Well, you can use drugs too, right? I'm not against drugs, but if you want to do it naturally, the fasting and the other thing are going to be important.

SPEAKER_00 31:48

Are there healthy fat people? Can you be can you be obese or overweight and be healthy?

Sleep, Stress, And Satiety Signals

SPEAKER_01 31:54

Um so yeah, it's not, it's not an absolute one-to-one. So, and of course, uh, there's a big difference between the types of fat, right? So there's the visceral fat and the subcutaneous fat. And there's a lot of examples of people who have relatively high levels of subcutaneous fat, and it doesn't do anything. So remember, fat in fat cells, which is stored under the skin, is fine. Fat in your organs, which is visceral fat, is not okay. It's it's actually super bad for you. So not only are there fat people like overweight by BMI who are metabolically healthy, there's the opposite. Normal BMI people who have a significant amount of hyperinsulin and organ damage. In fact, if you look in China a few years ago, they they looked at Chinese people with uh type 2 diabetes. The average BMI, it's changed because actually obesity is skyrocketing in China. But 20 years ago, I think they did this study. And type 2 diabetics in China were getting diabetes with a body mass index of 24, which is normal. It's not even overweight. 25 is sort of the cutoff, right? So these were skinny. So you get the skinny fat where you don't have a lot of the subcutaneous fat. So you don't appear fat, but you'll have a lot of this visceral fat. And you have the opposite where you have people who have a significant amount of subcutaneous fat, but not a lot of visceral fat and are metabolically quite healthy. So you can't always tell, which is why you need to do tests like you know, like the A1Cs, like the uh fasting insulins, fasting C peptides. You know, they talk about the Kraft test where you, you know, give the the bolus of sugar to see uh how high your insulin levels go and so on.

SPEAKER_00 33:41

There we we talked about the the epidemic of uh obesity that's in the United States and and around the world to a lesser extent uh since the 1980s and 90s. It's it's unrelenting, except a few months ago there was a paper in the JAMA about for the first time, at least by this reporting, it appeared to level off. I mean, time will tell if it's a fluke or anything. What do you attribute that to?

Why Calorie Cutting Fails Long Term

SPEAKER_01 34:08

I think it's because people are starting to pay attention to things that matter more. So we obsessed about two things for about 25, 30 years. One was calories, which is not the right thing. Again, calories is not a physiologic concept. And what I mean for that is go to any standard textbook of physiology, right? And you can look up any metabolic pathway you want, right? Whether you look up, you know, the the citrate cycle or whatever, you can look up metabolism of glucose, metabolism of triglycerides. Nowhere in this entire textbook of physiology, which will be, you know, this thick, will you find a diagram with calories, because that does not exist. Calories are not a physiologic concept. Glucose, triglycerides, proteins, amino acids, yes, not calories, because all of those are different. And so, but we obsessed about it. We tried to make everything equal, as if you know, 500 calories of eggs is the same as 500 calories of brownies. And guess what? They're not, they're not equal in any way. And it's always striking to me. It's like, God, like, I don't know how many times I have to explain to people. If you eat 500 calories of steak and eggs in the morning, right? Your insulin level doesn't go up. You're gonna stimulate peptide YY, cholacystekinin, GLP. You're gonna be full until lunch or even maybe till dinner, right? You eat, drink 500 calories of a frappuccino. Insulin spikes way up. What's that gonna do? It's gonna push all those calories directly into storage because that's what it's supposed to do, right? You're gonna be hungry like 10 minutes after you drank that Frappuccino, right? You're gonna be looking for food because all your calories went into storage. There's no energy for you to use. So, how is those calories the same? And people say a calorie is a calorie. It's like, no, they're completely different. The very minute you put those calories in your mouth, your body responds with hormones that are completely different. So they're different. All it means is that eggs are less fattening than brownies or Frappuccinos. Well, duh, that's common sense. So why do you say a calorie is a calorie? So I think getting away from that whole notion that all calories are equally fattening is important. I think fasting has made a huge comeback, which is very important because, again, it's the most efficient way to lower your insulin levels. And it's a very traditional way of treating, you know, weight gain, right? If you want to lose weight, don't eat, right? That's fasting, right? And it works. It's not fun, but it works. So I think that sort of understanding has sort of started to move in the right direction. The idea that fat, so the other thing we obsessed about was eating less fat, right? So you live through the 70s and 80s where fat was just you couldn't eat it, you were gonna get a heart attack. And then all of a sudden, and and and what I always think is hilarious is that so then all of a sudden they started noticing, hey, people who ate nuts, they were pretty healthy. People who ate avocados, they were pretty healthy, fatty fish and olive oil and all this stuff. That's all fat, you know. Um, so then they had to coin this term healthy fat. But the the funniest thing is that, you know, we obsessed about fat, and then we had this um this French paradox, if you remember, this whole discussion about why French people were eating cream and butter and stuff and cheese, full fat cheese, and we're eating this, you know, skim milk reduced fat cheese. And they were having rates of heart attacks, like a third of the rate of Americans. And we're like, this is a French paradox. There was no paradox. The fat didn't contribute to heart disease. That was all just a misunderstanding, right? So we've moved past that a little bit. The other thing that uh was funny, I don't, again, I don't know if you remember these step one, step two diets. So this was the National Cholesterol Education Program. And this I learned about this in you know medical school, because this was from the 90s. This was the sort of heyday of the low-fat era. If you had a heart attack, you got the step one diet, which was less than 10% of calories as fat, which is very low. If you got another heart attack, you got the step two diet, which was less than 7%, which is essentially zero fat. It's really, really hard to eat. And the funny part about these diets is that people did way worse when they did the studies. The people on these super low fat diets were eating all white bread and white rice, and they're eating tons of carbs, they're gaining weight, and not understanding why. They're like, but I'm eating low-fat pasta, I'm eating low fat this, low fat this, I'm eating lots of bread with no butter and stuff, you know, lean, you know, everything, right? It's like just crazy. So that was the two things that were really super damaging to the health. And the other thing that sort of snuck through was the ultra-processed foods. So the problem is that when the American government said you should eat less fat, that opened the door like a Trojan horse because low processed foods could be low fat, right? It's very hard to make food low fat. If you know, if you have beef, it's beef, right? It has a certain percentage of fat, and that's it, right? Avocados, you don't Have low-fat avocados. But if you process it, you could do whatever you want with it. So the idea eventually became processed low-fat foods were better for you than high-fat, regular, natural foods. And it's a very destructive attitude. You look back on that and you shudder. And honestly, people don't even believe me when I tell them about what happened in the 80s and 90s about these low-fat foods because it's so, it was so bizarre to most people. But that's what we live through, right? And so now the ultra-processed foods dominate the American diet. And the problem with the processing is that one, they tend to create a lot of hedonic hunger, right? So they process these foods and make them as palatable as possible because they want you to eat more, right? They want to sell more food, which means that you need to eat more food, which means that not only does it have to be very high in, you know, pleasure, that is hedonic hunger, stimulate a lot of hedonic hunger, it has to not make you full, right? Because if you get full, you can't eat anymore and they can't sell anymore. So at the same time, they're stimulating this hedonic hunger. They want to minimize this sort of satiety. So you get foods like cheese puffs and stuff, which you could go through a whole bag of those or a whole bag of cookies. Easy, no problem. Like, you know, because they're they they don't create any satiety. They've gotten rid of all those satiety factors. Like you can't do that with normal foods, right? If you eat a hamburger patty, one or two is delicious. Could you eat 35? I doubt it. I certainly couldn't, because you're gonna be nauseated because of those satiety hormones. But could I eat a whole bag of Cheetos? If somebody told me to, I would, right? I don't want to, right? It's obviously super bad for you, but you could. It's not hard to do because there's no satiety there, right? So that's the whole point is that it I think the tide is turning. We're looking beyond calories, we're looking beyond this sort of low-fat dogma. We've gotten that we've I think we've gotten through, but there's still this whole thing about saturated fat. And then now we're turning the tide on sort of ultra-processed foods as well. We're losing that fear of fasting. So I think there's a lot of good things happening here. And the more we can talk about these issues, other than calories, because it's like, you know, you know, we've been talking about calories like for 50 years. Cut calories, cut calories, cut calories. Obesity did nothing but go up. The minute you start going past calories, now you're actually getting somewhere. Let's cut out ultra-processed foods, let's do the fasting, right? Really, really important. And that call comes back to eating behaviors and uh, you know, the hunger that we we talk about.

Hyperinsulinemia Versus Insulin Resistance

SPEAKER_00 42:55

Yeah, I mean, the awareness of ultra-processed foods as being harmful is certainly increasing. And it, you know, if they're you know, functionally the the met maybe the metabolic equivalents of cigarettes, why aren't we treating them more that way? Why don't we go even further in uh you know stigmatizing them?

SPEAKER_01 43:16

Yeah, yeah. It's it's it's important actually, because there are other cultures. If you look at the Italians, so Italy has a much lower level prevalence of ultra-processed foods and Japan too. So in the United States, about 70% ultra-processed foods. That's the that's the food environment that we find ourselves in. In Italy, it's about 20, 25, so much, much lower because they have a very strong food culture. It's not that they don't like food, Italians love food, right? Everybody knows that, right? The food is the best in the world, right? But the thing is that they don't eat ultra-processed foods. You go to like places they're eating, you know, their traditional foods that they've always eaten. You go to places like Spain, fresh seafood everywhere, right? Fresh squid, fresh fish, whatever, but real food, right? Not food that comes in a box, not food that's ultra-processed with a bunch of chemicals in it, right? It's it's all real food. And so this is there because they've had a strong food culture, they never replaced their foods because you know, in the United States, there was a huge push to replace normal foods with ultra-processed foods because there is this idea that if you could process them, get the fat out, it's better for you, right? It's not better for you, it's much worse for you. Whereas other cultures have resisted that and stuck with their natural foods and their obesity rates are much, much lower. Italy has one of the lowest rates of obesity in Europe and they love food, right? French people, people are like, why are the French so skinny? The French love food, right? You know, they they they obsess about this stuff, right? Their sauces and the cooking and this, using butter and cream and all this stuff, right? But real food, right? And that's the that's the difference. I mean, it you have to really go way past the these sort of um simplistic notions of calories. Carbohydrates is is a more important concept, but there's nuance there too, right? Because there's a lot of other things that can influence the insulin uh secretion. So, yeah, so so many interesting things, like sort of beyond calories. That honestly, the science of weight loss is is fascinating and almost never talked about. Like to me, I find it fascinating. But then honestly, I mean, I've read a lot of books about weight loss and almost in a lot of articles, and like 90% of them, including the obesity medicine people, are focused on calories, calories, calories, calories, calories like hello. There's a lot out there other than calories. There's the processing, there's the uh insulin, there's the cortisol, there's the GLPs, the GIPs, the sympathetic tones, there's the hedonic hunger, the the uh food addictions, there's uh conditioned hunger. There's so many other things you need to talk about and know if you want to be successful.

SPEAKER_00 46:20

There's so many, so many great things in this book. Uh I have so many other questions with you before you, but I want to be respectful of your time. Maybe I'll just end up with one last question. Is there any final thought or you want to leave the people with, or any any question I didn't ask you that you'd like to talk about?

Can You Be Fat And Healthy

SPEAKER_01 46:38

Yeah, uh, I think the only other thing is that I tried to make the book very sort of uh user-friendly. So I've sort of put together sort of uh the three sort of most important sort of golden rules of uh weight loss. And uh the most important really is sort of of uh you know reducing ultra-processed foods, increasing fasting, and then create the you know, develop these social habits that are uh you know supportive, really, because we actually the the the the people we surround with ourselves with actually play an outsized role in all behaviors and eating behaviors no different, right? So if you eat salad, if if your friends are eating salad, you're eating salad. If your friends are eating french fries, you're eating french fries, right? And so that's really, really important. That's why the support groups and your community is actually vital. So it's it's the most important thing, I think, that nobody ever talks about, right? But you do have to, you do have to find that supportive uh community. And those are the most important things. And honestly, you know, these are not rules that I just sort of thought up yesterday and put them in a book, right? These are practically the oldest rules ever, right? If you want to lose weight and you ask your grandmother, she'd probably tell you, don't eat junk food and don't eat all the time, right? Those are the two biggest things, right? And if you want to change any behavior, find some friends who will do it, right? If if your friends are playing basketball, you're playing basketball. Your friends are playing video games, you're playing video games. If your friends are just going out to eat, you're going out to eat. That's just life, right? So find your group that can lead you to those healthy choices. But this is true for any uh behavior. And so it's like it's not like the latest and greatest. Oh, do this, do this, do this. It's like these are rules that you could ask your grandmother or your grandmother's grandmother, and they'd still say, that makes sense. You should do that. Right? It's the ancient sort of wisdom, it's the sort of Lindy law, you know, it's like the stuff that's really survived through the ages. And then I've put together sort of 50 sort of weight loss tips, sort of uh less important things to focus on. So hopefully it's very useful. Uh, hopefully, it not only uh helps shed a deeper light on the sort of underlying science of weight loss, but also some practical tips on it.

SPEAKER_00 49:02

Yeah, it's a wonderful book. I highly recommend it. We've been speaking with Dr. Jason Fung, and the book is The Hunger Code, and it's it's coming out this week. You can order it on Amazon, Barnes Noble's independent bookstores, or your local library. Jason, thank you so much for taking the time to chat with us today. We really appreciate it. Thanks so much, Robert. It's great fun.