Instant Genius - Why understanding what makes us hungry is key to weight loss

Episode Date: March 6, 2026

Chances are that if any of us are looking to drop a bit of excess weight, the first thing we’ll attempt is to cut down the number of calories we’re consuming. For decades, we’ve been told that balancing the number of calories we put into to our bodies with the energy that we burn can help us to maintain a healthy weight. While this is true, could it be that we’re putting our attention and effort in the wrong place and that taking a bigger picture view of the factors that motivate our appetite is likely to be a much more successful strategy? In this episode, we’re joined by Dr Jason Fung, a physician and best-selling author based in Toronto, to talk about his latest book, The Hunger Code – Resetting Your Body’s Fat Thermostat in the Age of Ultra-processed Food. He talks us through the three key drivers that control our feelings of hunger, how our hormones are deeply connected with our appetites, and how the environments we live in have a profound effect on the food we eat. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Hello and welcome to Instant Genius, a bite-sized masterclass in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor, a BBC science focus. Chances are that if any of us are looking to drop a bit of excess weight, the first thing we'll attempt is to cut down the number of calories we're consuming. For decades, we've been more. told that balancing the number of calories we put into our bodies with the energy that we burn

can help us to maintain a healthy weight. While this is true, could it be that we're putting our attention and effort in the wrong place? And that taking a bigger picture view of the factors that motivate our appetite is likely to be a much more successful strategy. In this episode, we're joined by Dr Jason Funk, a physician and bestselling author based in Toronto to talk about his latest book, The Hunger Code, resetting your body's fat thermostat in the age of ultra-processed food. He talks us through the three key drivers that control our feelings of hunger, how our hormones are deeply connected with our appetites, and how the environments we live in have a profound effect on the food that we eat. So welcome to the podcast. Thanks so much for joining us. Thank you. Thank you for

having me. So today we're talking about your new book, The Hunger, longer code, resetting your body's fat thermostat in the age of ultra-processed food. So at the moment, I'd say there's an awful, if you walk into a bookshop, the bookshelves are full of books detailing all manner of different approaches to our diet, and many different ideas are there. But I'd say, like, the central idea of your book is perhaps a little bit different from most that I've come across. So, you know, can you explain this sort of idea that underpins the book first before?

we get into the details? Yeah, so the main idea of the book is to try to understand what's causing the weight problem, like a weight gain or the obesity epidemic, from a sort of deeper level. And this is where it differs from a lot of other books, because, you know, like you, I've read a lot of books, but most of them talk about either calories or foods and not a lot about the science of weight loss, weight gain. So if you're trying to understand sort of why people are gaining weight, you have to say, well, it's not enough just to say eat fewer calories because you need to know why they were eating so many calories in the first place, right? If you don't understand why they're doing it, you actually have no hope of doing it. And it's really quite simple, right? We eat because we're

hungry and we stop eating when we're full, right? That's it, right? So if the problem is overeating, really you should be focused on the problem of overhunger, if you will, right? That's the real problem. So you get to the even more interesting question. So then why are people hungry, right? And it turns out that there's three different types of hunger, at least. There's probably more. But there's the sort of physical hunger, which we all think about as, you know, your stomach's growling and all that sort of thing. And that's really driven by hormones, right? It's not simply that you haven't eaten in a while. It's certain hormones make you hungry. Certain hormones make you full. And certain foods, for example, will stimulate those satiety hormones and others won't. So they're very different.

If you eat a full buffet and you're really full and somebody says, here, have another pork chop, you're like, no way, right? But if somebody says, here, have some apple pie, you'd say, sure, right? So there's a difference because those two foods are very different in terms of satiety. But then there's also the emotional hunger and also the social hunger. So all three, the physical, the emotion on the social, play a role in this sort of. driving hunger, which is driving the eating behavior that's leading to the obesity epidemic. Yeah, so we'll get into these three sort of key areas that you discuss in the book in a moment. But I think if you're indulge me, I'm sure you get asked this a lot of times.

You mentioned they're calories. So for a long time, we've been told that in order to lose weight, we need to balance calories in versus calories out. It's a simple matter of physics, we're told. And, you know, people think, well, you know, what's wrong with that? Surely it works. It absolutely does not work. And that's really been born out over like 50 years of virtually everybody trying.

And honestly, this is the same thing I was told when I went through medical school. So why doesn't it work? It's because it's not just about the calories, right? So calories is the food energy, right? And if you think about what happens to the body, body fat is just a store of calories, right? So if you eat fewer calories, your body has to balance that somehow, right? So either it's going to release, say you eat 500 calories less of food, your body can either release 500 calories from your stores or it can burn 500 fewer calories, right?

And you don't lose any fat. So either one balances the equation. So there's no problem with physics here. But the problem is which one your body does makes a huge difference. On the one hand, you're not going to lose weight. So if your body releases the body fat, great, right? You're feeling fine. You're losing body fat. But what if it chooses the other one? What if it chooses to burn fewer calories? Well, you're not going to lose body fat, but you're burning fewer calories. So you're feeling cold, you're feeling tired, you're feeling hungry, and you're not losing weight. And the problem is the science says that virtually when you just cut calories, that's almost always the case. So you don't get to decide which when your body does. It's all about your hormones. are a key sort of point running through the entire book. So let's have a look at some of these different types of hunger.

So homeostatic hunger is one of these. So that might be a bit of an intimidating word, but you call it sort of physical hunger. So, you know, what do you mean by that? Yeah, so homeostasis is just a fancy word that means sort of balance. That is your body tries to balance. And this is the idea of the body fat thermostat, which is that your body always tries to balance at a certain stable,

level. And it's like your thermostat in your room, right? You set a certain temperature. It gets too hot. It turns on the air conditioning. It gets too cold. It turns on the heat. Your body sets an ideal weight as well. So if you're overweight, the question is not calories and calories. The person is what's pushing your thermostat up so high? And it's really about the hormones again, right? Certain hormones are going to push your thermostat up. We know that because if you give somebody insulin, if I start injecting you with a lot of insulin, your weight is going to go up. It doesn't matter how much exercise you do, how much willpower you have, or even what you eat. Your body gets the instructions and pushes your weight up.

Same thing with cortisol, right? So that's that homeostasis. So that's where homeostatic hunger comes in. It's driven by your hormones. And when you push that thermostat up, it's got to activate a mechanism to make you gain weight, which is going to activate the hunger, right? Just like your room thermostat doesn't actually heat up the room. It turns on your heat, right?

Same thing. When you push up the thermostat, it's the controller. But how it gets there is that it makes you hungry. So that's this physical hunger that we all think about. Turns out it's actually not the main driver of eating behavior. So if you've ever gone for a long time without eating, like if you've ever gone like two, three days, which is start to feel that hunger. And I've done this. And what you realize is that that actually, I feel that very rarely. Because food is quite available, we eat on quite a regular schedule. So we rarely get that really sort of driving physical hunger. So then the question is, what are the other types of hunger that could be driving it. And there's this emotional hunger, which when you look into the scientific literature is called hedonic hunger. And hedonic hunger just means relating to pleasure.

And the idea is that we eat because it's pleasurable, because it gives us, you know, comfort, we feel better when we eat. It's like dessert, right? You've already eaten a full meal. There's no reason that you need to eat from a physical standpoint, but you do because you want to. It makes you feel better. And this is this idea that, you know, it's pleasurable. So you get these dopamine spikes and so on. And the problem, particularly with ultra-processed foods, is that that is deliberately, those foods are deliberately engineered to crank up the pleasure, and there's multiple ways they do that, while at the same time minimizing the satiety. So therefore, you can keep eating them, right? Just like a bag of potato chips or, you know,

cheese puffs or something. Like you just keep going, keep going, keep going, you can't stop, right? And this can tip over into food addiction. But then when you realize, that it's the emotional hunger that's driving it, you can't just say eat less or it's food addiction that's driving it. If you're an emotional eater, you need to deal with the emotions. You can't simply say eat less because you've never dealt with the underlying emotion that's driving this eating behavior. And the third one is this sort of environmental or social hunger, which is called, again, when you look at the literature, it's called conditioned hunger. And conditioning just means that you can pair two things together and then one will trigger the other. So,

So the classic experiment is Pavlov's dogs, where if you give dogs food, they will get hungry. They'll salivate. If you ring a bell and then give the dog's food, they quickly learn to associate the two so that when you ring a bell, but don't give them the food, the dogs will still get hungry, right, because they're anticipating the food. Now you think about what happens in modern day society. We've paired food with almost everything we can go. Like, you know, in the morning, you get up, you must eat.

You get a coffee. Oh, you must eat. Oh, it's lunchtime. Oh, you must eat. Oh, it's after school. You must eat. Dinner, you must eat. You get in the car. You're eating. You're in front of the TV. You're eating. You're watching a sporting event. You're eating. In the movies, you're eating. And all of a sudden, like, you go to the mall and then there's billboards with food. There's television ads. There's ads on your computer. You know, every single place you turn, there's food. So what's happening is that you're creating a lot of conditioned hunger. You've conditioned it. You've paired the two so much that you walk around. And Everywhere you go triggers this hunger. And this is what some people called food noise because you're walking around and you're thinking, why am I always hungry? Why am I just date?

Like, why am I always hungry? And until you realize that, hey, it's because you're so conditioned. You go to a meeting, for example, like at work or something. And nowadays, every single meeting has like a plate of bagels, a plate of cookies or whatever. So now you go to a meeting and you're expecting food, right? So we are Pavlov's dogs, and that's a problem. Luckily, you know, there's an entire field of behavioral psychology that deals with this and how to extinguish it.

So there's extinguishing, there's counter conditioning, there's all this stuff. But again, this social environmental hunger is actually a totally different toolkit than emotional hunger, which is a different toolkit than homeostatic hunger. So if you think that it's all about calories, you're not getting into this sort of deeper understanding of the hunger that's driving the eating. And, you know, to the man with a hammer, every problem is a nail, right? So, you know, when all we had is eat fewer calories, you'd have things like, oh, your problem is that you're not sleeping enough. So you're gaining weight. So the problem, so the solution is to eat fewer calories. Like, why? The solution is actually

to get better sleep. Or if your problem is that you have, you're eating too much ultra-processed foods, The solution is eat less ultra-processed foods, not eat fewer calories, right? The whole thing is completely, there's a huge mismatch between the two things, and it's because we never thought about the problem of weight gain deeper from a scientific standpoint. And it's crazy because we have years of physiologic research to back this up. The minute you put a food in your mouth, the responses are completely different. But there's also this whole aspect of, you know, behavioral psychology,

an aspect of emotional health that were completely missing with this calories argument. Yeah, so let's run through a few of the things that you brought up there in a bit more detail. So you mentioned the hormones, so insulin and cortisol. So I think most people will have heard of these, but in a different context. So insulin, probably in the context of people with diabetes and cortisol in the context of people suffering from stress. So what role do they play in our hunger and our appetites? Well, those are the hormones, the main two hormones that really push up that body fat thermostat, which is then going to trigger off the hormonal hunger, the homestatic hunger, which is going to make you want to eat.

So insulin, for example, is a hormone. And it's a normal hormone. The problem is when you had too much of it. So the modern day foods are engineered to really generate a lot of insulin. And this was originally because there was this whole, remember the low fat movement, right? So when we are eating a lot of carbohydrates, it tended to be a lot of refined carbohydrates, like a lot of white bread. And those refined carbohydrates would spike our insulin.

So the question is, okay, so what does insulin do? So insulin's job, and it's a normal hormone. The job of insulin is to tell our body to store calories. And your body's going to store calories as body fat. That is normal job, right? But what you're supposed to do is have a sort of normal level of insulin. insulin, you store a little bit of the calories. And then when you don't eat, insulin's going to fall. And that's triggered for your body to release the fat. Right. So the question is what happens when you

eat foods and you're eating constantly, right? So every time you eat, insulin's going to go up. So instead of eating three times a day, now you're eating eight times a day, nine times a day. And that's actually just an average from some of the studies that show how often we're actually eating. A lot of times people just have a little bit of this and they don't count it, right? But the point is that what happens when you have so much insulin? Well, that's not hard to figure out. Insulin's job is to tell you to store calories. So if your insulin's way too high because of the foods that you ate,

because of the ultra-processed foods and because you're eating them so often, well, duh, your body is going to get the instructions to store more calories. So you eat those, say in the morning, you have a sugary coffee drink and a big donut, right? All a lot of starchy carbs and stuff. Insulin goes way up. So you might eat, say, 800 calories. Well, the high insulin is going to tell your body, take these calories and put them all into storage. So all 800 calories goes into your body fat. So an hour later, your body's like, hey, I have nothing here, right? Your heart, your liver, your kidneys, is like, you need to go eat some more. So it's going to trigger hunger. So you're hungry at 10 o'clock, right, instead of like in the morning. Now instead, imagine that you ate a three egg vegetable omelet in the morning. Well, you're sort of, you're sort of, a full, insulin doesn't go up, all those calories are floating around. Your body's like, okay, I'll use them for energy. And you're full at least until lunch, right? So even though those were the two same number of calories, 800 calories, the response is completely and utterly different.

Why would you even pretend they're the same thing? Like eating, and all it means is that like certain foods are more fattening than other foods. Well, like, duh, is that not just common sense? like cookies are more fattening than broccoli. Brownies are more fattening than eggs. Like, duh. Like, you know, I bet you if you ask your grandmother, she'd say, why wouldn't, why would they be the same, right? There's nothing the same about these two foods.

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I can bosh that back in no time at all. And five minutes later, I could have a full meal. Whereas like you say, if I eat a plate of broccoli or spinach with this similar amount of calories, probably will feel full. So what's happening in our digestive system there that has this effect? Yeah. So it's really a lot of different things. create the satiety. So that's why I say it's a nuanced thing. It's not just calories. Your body doesn't

get full just on calories. There's actually multiple, multiple levels of hormones. So there's a hormonal system called GLP 1 and GIP. And they're very topical these days because of the weight loss drugs, which are basically, you know, everybody's heard of them and been on them now. And they act on that system. So that system basically tells your body to stop eating, right? It's a satiety. hormone. And if you think about it, this is natural because when we start to eat, we need to know when to stop eating. So when we start eating, your body will have a natural stop signal. And GLP is one of those stop signals. And so if you're eating a lot of proteins, for example, that's going to stimulate a lot of GLP 1. If you're eating a lot of fiber, that's going to also

stimulate a lot of GLP 1. Whereas the muffins, the donuts, these highly refined foods, basically don't have that GLP1 effect. But that's only one of them. There's also something called peptide Y-Y which reacts to a lot of protein. There's colostocycinone, which is when you eat a lot of fat, that satiety turns on. There's also stretch receptors in the stomach where if you stretch the stomach out, it's going to send the signal to your brain, hey, we're getting full. You need to stop eating. So what happens when you eat broccoli?

So if you drink 800 calories of a creamy latte with a lot of sugar and syrup and stuff, well, it doesn't stretch your stomach up much because it's liquid. So it's actually going to go into the stomach. going to go right out of the stomach, right? If you take the equivalent calories of, say, broccoli, broccoli is sort of big and puffy, right? It's full of fiber, full of water. If you took 800 calories of broccoli, it's actually huge. So your stomach is going to start to get full. So therefore, you're going to turn on satiety and then stop eating. So again, two different foods, same calorie, but dramatically different effects because of the difference in digestion, right? So it's not simply,

it doesn't go from calories to increase body weight, right? You have a food which contains calories and all this sort of stuff, then it has to be digested, right? And that means it goes down in the stomach, it's churned around, then gets put into the intestines. But then from there, it goes digestion to absorption where it has to go into the blood, which then affects your hormones, which affects your weight, right? So there's this whole well-worked-out process of how you go from food to weight gain,

but it's not calories to weight gain. It's this huge process. And in the book, I talk about, like, there's 10 different ways you can affect digestion. There's 10 different ways you can affect absorption. There's like 10 or 11 hormones that play a role. So all of these things make a difference. I mean, another example of a hormone that plays a role is the sympathetic nervous system, for example. And this is not because you can always manipulate it.

But a lot of weight loss drugs, a lot of old weight loss drugs, talking about Uzumpik, have affected this. So there is an old drug called in this. 60s called amphetamine, which is called speed, which is also crack. And that affects your sympathetic nervous system, which is your fight or flight response. But what it does is it severely decreases your hunger. So, you know, obviously there's a lot of side effects with that, but it was a great appetite suppressant. And that's why it was used in the 60s. Nicotine, for example, is also a sympathetic stimulant. So people who smoke, they lose their appetite. And they lose weight. Right. So it's not a half.

calorie thing because none of these things affects your calories, right? And if you think about Ozempic, which is the current, or JLP1 drugs, which are the current sort of craze, what you have to realize is that they don't restrict calories. You can eat as many calories as you want, but you don't want to. And that's the key. Because you can physically restrict somebody's calories. I can do that by wiring somebody's jaw shut, or you do bariatric surgery, right? You cut their stomach so that they simply cannot take those calories. Did it work? No, barely at all. Nobody does these anymore. So let's move on to this sort of second pillar in the book then, which you mentioned, hedonic hunger, the emotional aspect to hunger and our appetite. You think, well, maybe it's kind of

obvious evolutionary that we're wired to be hungry all the time and to not only that, to enjoy eating. Yeah, and that's the key is that, yes, you are, we are wired to enjoy eating. That's why we all love these big celebrations. But the problem now is that the ultra-processed foods has tweaked that so, you know, like the 11, you know, sort of thing, right? And this is the idea that when you process a food,

you change how your body responds to it. So this sort of hedonic hunger, this sort of eating for pleasure, can be turned up to the level that you can't stop eating, right? And you might think, well, this is crazy, you know, that that doesn't doesn't happen, but of course it happens. It's not deliberate. Like we, there are lots of people who talked about how they engineer foods, right? So there's artificial colors, artificial flavors,

there's flavor enhancers, MSG, multidextrin, there's texturizers, there's emulsifiers, and so on. And it's not by accident. It's because they increase the pleasure that we eat to an unnatural level, right? And sometimes that tips over into food addiction, which is an addiction, something that you can't stop, even though you know it's bad for you. I've heard people say, well, that's ridiculous. You can't be addicted to food. But in fact, when you look at the research on food addiction, which has really exploded in the last five years, it's clear that it plays a very large role. And people say, well, it's all natural. How can you be addicted to food? And it's like, that's not true. Because if you think about, you're not addicted to food. You're addicted

to ultra-processed foods, right? It's the processing. That's the problem. Just like smoking, like It comes from tobacco plants, but is smoking addictive? Yes. Alcohol, you know, you ferment rice or grains or whatever. It's a natural product. Same thing with poppies. You can take poppies and process them into morphine. And then, yes, it is very addictive.

Same thing like here. You can take foods and you can sort of just take that sort of addictive piece and just tweak it to the point that you get the food addiction. And it's clear that like 30, 40% of people who struggle with their weight are actually addicted to food. So when you're dealing with addiction, you have to treat it differently, right? And you can't just say everything in moderation, right?

Like if you had a friend to his alcoholic, would you ever say, hey, just have a drink, everything in moderation, right? Like, you'd be the worst friend ever, right? Or if somebody was addicted to, you know, cocaine, would you say, just have a sniff, everything in moderation, right? It's ridiculous. Yeah, exactly. Because with addictions, when you start,

you can't stop. That's the problem. So it's the same. If you identify this addiction to, and people tell you all the time, I'm addicted to bread, I'm addicted to pizza, I'm addicted to chips, I'm addicted to sweets, I'm addicted to chocolate. They're telling you they're addicted. We just don't believe them. So how about, I think one thing that I thought when I was doing this is which I do myself is it's sort of kind of novelty or missing out. So let's say one of my favorite cuisines is Chinese. So I go for a Chinese meal and, you know, generally you'll share it in the center and I'll have the sweet and sour chicken, the ribs, the beef marla, fried rice, a load of seaweed and halfway three, someone will say, well, you know, shall we get the prawns? Shall we get

the chili crap? And even though I'm full, I'll just say, oh yeah, let's get those. You know, that can't be unique to me. Yeah, no, no, everybody does it, of course. And that's the hedonic hunger. You have to identify that, hey, you're not eating because of the physical hunger. You could eat the other thing. You want to. You develop the hunger because of the novelty. And that's part of the problem, right? If you ever have a monotonous diet, like where you only eat one thing, very soon you will lose weight.

Right. So they had these diets in the 1980s in China, for example. People were eating a lot of white rice. The issue was that that's basically all they were eating, right? Right. rice and vegetables, meal after meal, day after day. Because remember, in 1980, China was quite underdeveloped, so therefore just wasn't a lot of variety. So if you're eating white rice and vegetable day after day, it's a lot of refined carbohydrates, sure. But because of the hedonic hunger,

the minute that you are full, you are going to stop eating that white rice and vegetable, because you have another meal of that every day for the next 365 days. of that year, right? So that's that hedonic hunger. So this sort of explosion and food variety, which actually comes from a lot of the processed food, but, you know, also the sharing of cuisines too, right? And to some extent, of course, that's good because we know what we like. But once you understand, hey, this is a different mechanism altogether, right? This is not because I'm hungry. The key is to be mindful of that, right? It's not that you have to stop it because there are definitely going to be times.

Like, you know, when I go to Italy, it's like nothing's going to stop me from getting some pizza, right? It's like that just is not happening. But you have to understand it, right? As long as you're mindful of it, then you can say, yes, I understand that. I'm not eating because I'm physically coming. I'm eating because of the hedonic hunger, which is triggered by, you know, the thought of it. So therefore, what I'll do is I'll try to make up for it, right?

I might skip the next breakfast because, you know, that's just the regular breakfast. so I'll make up for it, right? But the mindfulness is a key part because you've identified, right? If you didn't identify, you might just think, oh, well, that's just a normal meal. But it wasn't because it was one that was eaten because of the hedonic hunger rather than physical homeostatic hunger. So you mentioned their addictions. So a sort of big part of that is habit formation. So does this play a big role in overeating or eating in ways that,

perhaps we know we shouldn't be. Oh, absolutely. And that really more touches along the third sort of pillar, which is this sort of conditioned hunger, which is this sort of social hunger, right? So what the people around us do plays a huge role in what we do, right? So if all your friends are you know, hiking for fun, you're hiking for fun. If all your friends are eating French fries, they're eating French fries, right? It's such an important thing. And you see this and there's lots of studies on it. So, for example, there's a study that says that if your best friend gets obese, becomes obese, your own risk of obesity goes up by like 170% or something, like ridiculously high risk. You can study military families when they move from one place to another

where there's higher obesity, their risk of obesity goes up. So, and you look at countries. You look at, say, Japan or Italy, for example, compared to the United States. Well, there are They're all very similar sort of developed first world nations, but the rate of obesity is strikingly different between the two, right? So Japan has one of the lowest in the world and the United States has one of the highest in the world. But you take the Japanese person from Japan and plop them down into the United States, and the risk of obesity just skyrockets, right?

It's like five times within one generation. By the second generation, your obesity rate has basically matched. the Americans. So it wasn't the fact that they were Japanese or whatever. The fact is it was the environment which was shaping you because you have to understand that the influence of others on our own behavior is sort of massive. That's why social influencers and stuff are so important because we understand that. So again, if you have an environment where you're eating all the time, you're expected to eat all the time, there's food all around you, there's food cues all around you. Well, you're, you know, out of luck, buddy. Like, that is not going to be good for your weight,

right? And you see this all the time. People write stories. I read a lot of stories of people, students, for example, they go, oh, you know, I lived in wherever it was, right? And then I moved to the United States to do school and I gained like 40 pounds, right? And then I went back home and my mother was horrified. It happens all the time. And then they're like, then I lost it all as soon as I was in, you know, France or whatever, right? You hear them all the time, right? And it's not calories and it's not willpower. It's not none of that.

It's the food environment and the influence of the people around you. When I go out to eat with my high school friends, the diet is terrible, right? A lot of, you know, fried foods, a lot of French fries. But when I go out with my family, hey, my diet's pretty good, right? What's the difference? Like, it wasn't me. It was the people around me. And that has a huge difference.

So who you eat with is going to make a difference in how much weight you gain. And that's just being human, right? So why deny that, right? Why say it's all about calories? Because ultimately it wasn't about the people around me. So you have to design that environment. You're trying to take away the food cues. You're trying to break all those habits.

That's actually one of the most important things that we never talk about is the environment. It gets lost, I think, this obesity in this. we label it as a personal willpower sort of problem, then we start to blame people. But it's like, that makes no sense. Like in the United States, 70% of people are overweight or obese. So if you had a school and you had 100 children and one failed, you might say, well, that's a child's fault. But what if 70 children fail?

Would you say it's the children's fault? Or would you say, no, it might be the teacher, it might be the school, it might be the learning environment, right? A systemic environmental problem. So it's the same thing here. It's like if 70% of people are overweight obese, it's not an individual problem. It's a systemic problem. And what is that problem, right?

It could be ultra-processed foods. It could be food cues. It could be food addictions. But let's think about it systemically and not just blame the victim. Yeah. So sort of coming off the back of that, like you mentioned, funnily enough, I lived in Japan for several years when I was younger. If you go to a 7-Eleven in Japan, there's a lot more healthier food options than there are. Even over here in the UK, like if I use a motorway service station as an example,

so, you know, I quite often will drive quite a long way and I'll get hungry. And my choices are burgers or fried chicken, usually. You know, so I don't, I'm hungry. I've got to eat something unless I prepare and, you know, pack something healthy beforehand. That's the only option I've got. And the same goes for a lot of people. You know, we're at work, we have a short lunch break. The options around us probably aren't very healthy.

It's sort of in our faces all of the time. So do you think there's something really that could be done about that? Like you're saying about like social groups and things. But how about like sort of nationally, you know, surely we can be doing something better. Yeah. And it just comes down to sort of social, like understanding what the problem is. So, you know, one, for example, this sort of focus on ultra-processed food. So the new dietary guidelines in the United States, for example, are making a big, big push into that.

So that's going to bring that into this sort of national consciousness. There's lots of things you can do from a sort of like think about the workplace, for example. So if I was in charge of a workplace, what would I do? I would say there's no eating at your desk, right? There's a cafeteria. That's the only place you eat because if you start letting people eat at the desk, what's going to happen is that they're going to be your conditioning that hunger, you're making it normal for somebody to eat. You have like food and people are smelling it. They're going to get hungry. That's not fair. Like get rid of the sort of, you know,

the birthday cake every sort of week sort of thing because again, it's simply not fair. And I would say all board meetings, for example, no food because you're conditioning people to eat, you know, because when they get in a meeting, they're expecting a plate of bagels, a plate of cookies or whatever, right? So there's so many things that you can do. No, no bowls of candy on your desk, right? And it's like, yeah, maybe you think I'm being mean, but what I'm trying to do is because people are struggling is simply not fair to somebody to tempt them with food all the time. Like it doesn't make any sense, right? So you can do it from a local standpoint, right? And the idea in your house, for example, is, you know, don't buy the cookies, right? Then you won't be tempted to eat them, right?

But there's so many other things you can do from a national standpoint, you have to start to say, okay, well, we're not going to allow, you know, certain things. Like in Japan, they don't, they there's a strong social pressure to not eat while you're walking, for example, right? And it's because it makes things filthy, right? But what happens is that when you start to restrict the places that you can eat, then you're going to change eating behavior. Like in the United States, in the UK, you can eat wherever you want, whenever you want, right? You can eat in your car.

You can eat on the street. You can eat, you know, at your desk. You can eat anywhere. I even saw somebody the other day eating in the elevator. And like, you don't need to do that, buddy. And it's like, okay, but when somebody else does it, it makes it okay, right? So when it's not okay, like in a lot of places, like, you know, you go to like Italy, for example, and they love food in Italy. But the food is always at a table.

There's a time and a place and people you do it with and other times, no, right? Whereas we've lost that sort of guardrail, right, to say that, hey, you're in the office. This is not an eating place, right? There's a cafeteria for that, right? Or this is school. This is not an eating place, right? There's a cafeteria for that, right? But now we give them snacks at their desk and so on, right?

So we've taken that away and we simply have to say, look, we understand that we don't want to be, you know, conditioning this hunger, right? We don't want people to think that every time they come to a meeting or every time they sit down at their desk, they're going to eat, right? So therefore, let's just make it a rule that. We're not going to do this anymore because it's going to make a difference long term. And these little habits are everything, right? It's like, it's like, you know, when you create that habit, the key is that it doesn't require willpower going forward because it's like brushing your teeth. You don't think, oh, should I brush my teeth today? You don't, right?

Because it's such a habit that the dividends pay off year after year, year after year, right? The same thing with habit. Like, you don't need the willpower. Once you create that habit that, hey, I don't. don't eat at my desk. I don't eat in front of the TV. All of a sudden, you've taken away that conditioned hunger, right? There's a totally different aspect. It's a behavioral psychology aspect, not a calories and calorie out. And if you don't lose weight, hey, it's your fault, right? That's such a simplistic way of looking at things. So we've covered an awful lot there,

but sort of by way of summary, there's obviously a lot more in the book. So I'd recommend checking that out for anyone listening. But you have what you call three golden rules. So can you just, by way of closing, run us through those, please? Yeah, so the golden rules are sort of the most important rules. There's like 50 weight loss tips as well, but the most important rules. And one is don't eat ultra-processed foods because they really cut across so many different lines of hunger, right? The physical, the emotional and the social. Two is to have an adequate fasting period.

So again, make sure you set aside that time that you know you're not going to eat. So that just like brushing your teeth, you know, hey, boom. It's seven o'clock. I finished dinner. There's nothing until breakfast. It's automatic, right? You need to be automatic because, you know, you make your habits, then your habits make you. Because the dividends just keep paying out over and over. So you need to make sure you condition that right in. And third is to create that social environment. You need to redesign your environment around you to be successful. And sometimes that means making sure that if you're going to meet your high school friends, do something else. Like go play basketball. Don't go and eat because you know when you go eat. It's a mess, right? I know that. What do I do? I go play tennis with them.

I go play basketball with them. So it's fine, right? I still enjoy them. They still enjoy me. But it has nothing to do with food, right? But, you know, same thing. Don't eat out of your dad. It's like redesign that physical environment because that's actually an incredibly

important aspect to why you're eating. And if you're eating too much, you have to understand, hey, which part is it. So that social environmental piece is probably the biggest piece that we never really talk about. So those are the three most important rules. And what I think is interesting is that they're not like new rules. They're probably the oldest rules in the book, right? Like honestly, if you're to ask your grandmother, you know, how to lose weight, she'd probably tell you the same thing. Don't eat junk food. Don't eat all the time. Right. That'd probably be her two biggest things. Eat real food. Right. So it's like, okay, I'm not trying to reinvent the wheel. I'm trying to just bring us back into the 60s and 70s where

where people were like, yeah, they recognize the wisdom of those sort of rules as opposed to eat fewer calories. It's like, does that tell you about who you're supposed to eat with, where you're supposed to eat, why you're eating, when you're eating? Does it tell you anything about how to develop a decent plan? Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Dr. Jason Funk.

To discover more about the topics we've just discussed, check out his book, The Hunger Code. setting your body's fat thermostat in the age of ultra-processed food. If you liked all you just heard, then please consider subscribing to Instant Genius on your preferred podcast platform. If you'd like to see our guests and hosts in person, then why not check out our YouTube channel at Science Focus. The current issue of BBC Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines,

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