Episode 17: Dietary Fasting ft. Dr. Jason Fung

Episode 17 features Dr. Jason Fung, a world-renowned nutritionist and author of "The Obesity Code". Geoff, Michael, and Dr. Fung discuss the nuances of health, diet, and fasting!




Geoff: Hey thinkers, welcome to this week's THINKING Podcast. I'm your host, Geoff Woo.

Michael: And I'm Michael.

Geoff: And we're really excited to have Dr. Jason Fung today as our guest. He's a Toronto based nephrologist, but he's made waves as the author of The Obesity Code. It's really making waves in the nutritional space and the fasting space, and has laid out a new way of thinking about weight, diet, and daily regimes. So we're excited to have you here and dive into some of the ideas, and get your thoughts on the whole biohacking movement.

I think one thing that I want to start off with is that, I think for a lot of our community members and our listeners, we came to this notion of intermittent fasting from an enhancement perspective. Where, I think we were always relatively healthy people, most biohackers are generally into fitness, into increasing their cognitive performance. And one of the interesting notions that we stumbled upon when we're looking into nootropics and other interventions was that, fasting was one of the most compelling ways to increase adult neurogenesis and very interesting data around ketone metabolism for brain function, cognitive function. And it's interesting to see that you've come to intermittent fasting from a weight loss perspective. I wanted to lay it out and start from there. What brought you into nephrology, into diets and intermittent fasting?

Jason: Yeah, it's quite interesting because the thing about it is that it's a ... So, I deal with kidney disease, that's my specialty. By far and away, the most common cause of kidney disease is diabetes, type 2 diabetes specifically. And I spent a lot of years just treating people with dialysis, that kind of thing. It kind of dawned on me that we weren't really doing a lot of good. That is, that we could treat their kidney disease but they were still getting it, so they were still sick. And it was kind of obvious after a while to see that if you have diabetes, which is causing kidney disease, then obviously, you don't want to treat the kidney disease, you really want to treat the diabetes. Right? Isn't that like super obvious?

It is to me now, but it wasn't then. It's because they tell people, including doctors, that type 2 diabetes is a chronic and progressive disease, but it's not. It's actually completely reversible. Because again, and everybody already knows this, that if you lose weight, then your diabetes goes away. So if it's completely reversible, so then why don't you reverse it? So, that's kind of how I got into it.

I started first by saying, okay, how are you going to reverse the diabetes? Well, you got to fix the obesity. Then, how are you going to fix the obesity? Because again, that's one of these things that everybody seems to have given up on. Right? Because the current treatment paradigm is so bad, that is cut a few calories here and there, portion control, eat less, move more, which is what every single person medically ... Medical person, doctors, dieticians tells you. It's so abysmally bad, the results, that everybody's kind of given up, well, obviously you can't treat it.

Well, it's like, okay, but the disease of obesity has only been here for 35 years, since the mid '70s, obviously it's not a genetic disease. All these people talking about the genetics of obesity, it's like, you're so wrong, because our genetics have not change.

Geoff: Yeah, I think if you look at ... I think there's an interesting graphic that you really show the curves go viral, infestation of obesity, growing, about 30 years ago. The curve just spiking just 30 years. Yeah, if it was a genetic condition we should always ... Two-thirds of Americans or people should be fat, and that's clearly not the case.

Jason: And it's the same with India, and China, and places like this, that have become Westernized. We're seeing exactly the same sort of thing. And again, there's no possible way that anything genetic has anything to do with what has happened. So it therefore, must be a diet lifestyle. So then, that's what you have to fix.

So for all the money that we spent on genetics of obesity, it's not useful. And I don't know why nobody kind of gets that?

So, then you have to go back to what causes obesity, and it turns out that calories is really the wrong thing to be talking about because calories ... Your body just doesn't care about calories.

Geoff: Yeah, calories in does not equal calories out, is one of the key taglines.

Jason: You reduce your calories in, your calories out goes down. Okay, we've known that for 100 years. If you eat less, your metabolism slows. It's just like if you earn less money, then you will spend less money. They're not independent. And it's the same thing for the body, and this is the reason that these weight loss solutions never work, because you reduce your calories, your body reduces calories out. You don't lose weight, the weight comes back. And that was really the thing. It's not a caloric problem.

Geoff: And, what are some of the ways that your body reduces the calorie expenditure there?

Jason: It's called the Basal Metabolic Rate, you can measure that, and that's the energy that it takes to keep generating body heat, keep your heart working, keep your brain working, and all that kind of stuff.

The thing is that this is why people on a diet just feel like crap, because they are expending less energy. So your brain is getting less energy, your heart's getting less energy. You're feeling cold. You feel like crap. And the worst part is that you're not losing weight.

And, despite this complete failure, all the kind of obesity gurus just keep harping about calories. Well, does your body count calories? No. Does your body somehow have some kind of sensor for calories? No. So, then, who the hell cares about calories, right?

What the body actually cares about is hormones. That's the language of the body. So, certain hormones tell us to store energy as fat, and certain hormones will tell us to burn it and get our brain working better. So you have to fix the hormonal problem. That's how I kind of came to it. But more specific to your group, I recently released a second book called The Complete Guide to Fasting, which is kind of a follow-up to The Obesity Code.

The Obesity Code talks all about obesity and to a smaller extent, type 2 diabetes. And one of the solutions that works very well is intermittent fasting as well as low-carbohydrate diets, ketogenic diets, and so on.

Geoff: Yeah, I wanted to jump in here and ask. Kind of related the homeostasis question, if you have less calorie intake than your body sort of naturally adapts, it's very hard to get your ... I mean, the body's a well adapted machine to balance itself out. So one of our community members actually asked, well intermittent fasting is a timing version of caloric restriction, so why is intermittent fasting different from just like less calories in?

Jason: Yeah, it's completely different. And this is the thing that always gets me. The frequency of anything is not irrelevant. That is to say if you jump off a one-foot wall a hundred times, it's completely different then jumping off a 100-ft wall once. You jump off that wall, you die. You do a 100 of these one-ft things, you don't die. So it's completely different. If you have the average temperature of Death Valley, California, is 25 degrees Celsius. Oh hey, great place to go for a vacation, right? No, you're gonna like die in the day, and freeze yr ass off at night.

So, I don't understand why calorie should be completely ... Like, oh, frequency doesn't matter. Well it matters in everything. This is the same thing. It's not about calories. We have to get it out of our minds, calorie reduction has nothing. It has nothing to do with the body. The body just doesn't measure it, doesn't count it, doesn't have anything to do with it. The only thing that matters is the hormonal signals that it gets. So, the question is, eating the same number of calories all at once, versus spread out over the 16 hours of your waking day, is there a difference? Yes, there's a huge hormonal difference between the two.

If you look at the way that hormones are secreted, they're not spread out evenly throughout the day. There's a burst, and then it stops. So why does it matter. Well, think about the story of the boy who cried wolf. The way our body works is we react to change, and if something is constant, then we basically zero it out. Okay? So, if that boy cries wolf, then everybody starts to ignore him. That's just the way it works. So, if you yell at your kids, the first time, they go, "Whoa". When you yell all the time at the kids, they're like, "Yah, whatever." Right?

This is the same thing. It's homeostasis, your body gets used to a certain level. You see a baby sleeping in an airport. It's loud, but he's sleeping soundly. You put the same baby in a quiet house, and the slightly creak of the floorboard, that baby's up and crying and you're like, "Oh, my God."

This is the same thing. Your body actually adapts. If you keep a high level of insulin all the time, which is the major hormone that we're talking about with obesity, you develop insulin resistance.

Geoff: Yeah, I think that's one thing that I think it's interesting, where there's people that recommend eating six or eight meals a day, constantly eating. And given our understanding, and especially how you talk about insulin as a primary driver for obesity ... In your book, I think you make a very good argument, it is the causal, ultimate cause. Literally, that is bad for people because you're constantly having insulin spikes throughout the day. And yr basically, if your eating six, eight meals a day, that's like bad for people, which I think is very interesting.

Jason: Right, and if you think about it logically, it's like, well, how are you going to gain weight? Well, eat all the time. That's how you're going to gain weight. Yeah, that's how you're going to gain weight, so why would you eat all the time?

Geoff: So, you have this notion of your bodies set weight, and that's triggered by insulin sensitivity. Your insulin sensitivity drives the set weight that your body's going to try to return to. Can you unpack that a little bit? How that takes place?

Jason: Yeah, in The Obesity Code, one of the things that doesn't really get talked about is the time of time dependence of obesity. That is to say, if you've been obesity for 30, 40, 50 years, that weight is just really, really hard to come off. And the carbohydrates notion, like low-carb, is great, but it doesn't really address that because your diet can change. How do you account for the fact that your body has this kind of memory. It has this kind of set weight. It doesn't. And neither does the calories.

So, you have to really look at the way that the body works. If you develop more and more resistance, then what's happening is that your body keeps the insulin levels high in order to try and overcome that resistance. This is the knee jerk reaction, but it's actually detrimental because that high insulin tends to cause more resistance.

Like for instance, if you listen on your headphones all the time to load music, what happens is that you go a little deaf. So you turn up the volume. Right? Great idea, except that it's the high volume that's causing your deafness. So, you get a little more deaf, and then you turn it up again. And that's what the body does.

Geoff: The death spiral. Its really bad death spiral where-

Jason: Exactly. And that's what the body does. You have too much insulin, that's the primary causes. Because one, you're eating constantly throughout the day. And two, we're eating meals that are highly processed, which tend to spike insulin. So, as opposed to the '70s where we ate kind of three meals a day, we're eating kind of closer to six meals a day now. So that insulin is high all the time, which causes the body to become resistant to insulin, and in response the body secretes more insulin. That's your death spiral.

High insulin leads to resistance, which leads to higher insulin, which leads to more resistance. And that's your death spiral.

Geoff: And meanwhile, the insulin's causing you to store that fuel that you're eating. Signals to store fat, and also, I think you make a good point, that it's the counterbalance leptin which is the satiety hormones.

Jason: Yeah, the leptin, I think is a minor player in the whole thing. I don't spend a lot of time on it. People spend a lot of money researching leptin, thinking this was going to be the holy grail, but turned out not to be. What happens in common obesity is that you become resistant to leptin, and it's a question of why.

Insulin is telling your body to gain fat. Fat then secretes leptin, which tells your body to lose fat. But the problem is that if we're eating all the time, that insulin is kind of wins. So if the leptin stays high all the time, you just become resistant to it.

So, if you want to see in terms of power, what happens is that the insulin is primary whereas the leptin is secondary. If leptin were to win of course, then we'd all lose that weight again, which is what we want to do. But clearly, it's getting overwhelmed by the insulin.

Geoff: Right. Seems like you've gained leptin insensitivity, basically, as well.

Jason: Yeah, exactly. So, then you're not sensitive to it, so then it's not having its affect, and that's one of the problems. But the primarily reason it's not having its affect, is its getting stimulated all the time, but it's really getting beaten by insulin.

Geoff: I think one thing that you are highlighting to me, I think, just with a lot of conversations for more forward thinking, more ... I would say, just more disciplinary thinking medical practitioners, and doctors, is that it seems like a lot of the healthcare system, a lot of the classic medical school training, is very much about treating symptoms, and not treating ... And I think what you've called approximate charges, or like the symptoms, as opposed to the ultimate cause. And I think that you really break it down in terms of obesity, and obesity quite nicely. I think zooming out a little bit, why is that the structure? Because I think from an engineers approach and I think from ... I'm a computer scientist by training, so is Michael, and a lot of our community members tend to be in more physical science or engineering disciplines. That seems to be the training, always go down to first principles and build up the foundation from initial causes.

Can you help unpack that and get a sense of why is the health community so just focused on sort of the last proximate cause?

Jason: Yeah, and that's the real thing that is the problem because everybody's focused on that. It's just like if you are saying, why is somebody rich? Well, there's more money coming in than going out. Well, it's like, that's a useless answer. Or, why is so packed in this auditorium? Well, there's more people coming in than leaving. And every time you say, well, that's not helpful, somebody says, "That's the first law of thermodynamics. You know, calories in, calories out. It's a law. It's not just a suggestion."

Okay, but you're missing the whole point, which is what you're saying. Is that, you don't care so much that yes, there's more people coming in the room than out, the question is why are there more people coming in the room, than out? And that's when you have to start going back.

And the problem with medicine is that it's really focused on that last thing and I think because it's the most obvious and it's the most kind of ... The fastest way to make a drug kind of thing. It's like the shortcut. It's like, oh, here's the problem, just fix it kind of thing.

Geoff: Which is interesting, right, because where people get develop insulin ... They become insensitive to insulin and then we're treating it by giving them more insulin. Oh, you're not sensitive to it, so let's give you more insulin-

Michael: And you don't make money to not eat...

Geoff: And prices of insulin have been going up and to the right over the last what, 100 years? They've been steadily up and to the right?

Jason: Yeah. Well, the other thing is this whole calories idea. And you got to understand, that the calories is that kind of last proximate, oh, there's more people coming in than leaving. Or, there's more money coming in than leaving. Calories is the same. It's that last bit.

But you got to realize that it's ... So, everywhere else you can realize that just focusing in on the last little bit is useless, but there are a lot of vested interest in promoting this calories model. Why? Because they don't want you to know that say, "Hey, sugar makes you fat." Well, everybody knows that, right? But Coca-Cola doesn't want you to say well, "Coke kind of makes you fat." They want you to say, "Coke has calories, sure, but so does your broccoli. So, don't eat your broccoli, drink your Coke, yeah, you're good." Or they want to shift it to, "Oh, hey, you can drink a Coke or Gatorade, and if you run a couple miles, you're good." You're not good because your diet sucks and that's the real problem.

So there's a huge number of people that want you to believe. And I talk about this sometimes on my blog, is that there's all these people that ... In fact, my last week's blog was all about how Coca-Cola actually wants you to believe all about calories because calories is the perfect scape goat. Nobody sells calories. Nobody has a brand called calories. So, it's the perfect scape goat. Nobody gets hurt and you can deflect all your blame from your sugar water onto this nebulous thing called calories. Then you can say, well, it's not because you drank Coke that you're fat, it's because you're sitting on your ass all day. It's like-

Geoff: We're too lazy. Then you just have too many of those callers. Yeah, I think that's interesting. Yeah.

Jason: Exactly. For 50 years, and unfortunately what happens is that they spent millions of dollars paying doctors, paying researchers, to promote this idea that it's all about calories, when your body just doesn't give two shits about calories. It don't care at all.

Geoff: I think a couple of examples in your book I thought were really interesting about, that really put a point on it, are the fact that when you are stressed your hormone levels change, that your appetite and metabolism change. And also, pregnancy, similarly affects hormonal balance and your appetite, and your metabolism. It's not just your calorie usage drives your calorie intake, it's obviously a hormonal system that's driving that.

Jason: Well, look at puberty for example. If you take a boy and a girl going through puberty, at the end of puberty, that girl has about 50% more fat than the boy. That's just the fact, everybody knows that. They gain fat in their breasts and their hips, and so on. So what? Are 50% of the population, all girls are just lazy and gluttonous, and slothful-like? Hardly. It's clearly a hormonal signal that tells you to gain fat, because they need to reproduce.

It's a survival mechanism. It's something that you want to do. You have this idea, no, it's about calories in, calories out. So every single girl in the world decided to eat more and exercise less to gain more fat, and the boys all of a sudden didn't? Come on, that's just ridiculous.

The entire notion, when you actually think about it logically. When you think about it from a kind of scientific point of view, is ridiculous, but ... It's just like this whole thing about eat all the time. Well, where did that come from? Eat all the time, and you'll lose weight?

Geoff: Yeah, I think it really reflects onto like what are the interests. I think Coca-Cola, the sugar lobby, the corn lobby in the United States, these huge corn subsidies. There's corn farms in the middle of our country where they can only survive by government subsidies. Your General Mills, your food companies, they almost have to be promoting, hey, consume more things.

Jason: But they've got the money to do it. It's not just advertising. Advertising's fine because you and I know when you see an ad on TV it's paid for by Coke. Right, so that's fine. The worst part is when Coca-Cola pays scientists and doctors, and influences the American Heart Association. They take millions of dollars. These doctors are making out like bandits. They are taking millions of dollars to say that sugars not so bad. It's like, okay, well ...

And I wrote about this one time, I called them traitors because really they're supposed to be looking after our health, but what they've done is taken a lot of money to say that these things, which are clearly detrimental to our health are okay, and it's all about calories. Yeah, it's a real mess out there.

Geoff: Yeah, and I think that's why I think your work, and just having our grassroots community's important. I want to ... I think it's legitimately, fasting is the cheapest intervention that we can all promote with the biggest outcome. I think that ratio ... There's no drug that we're making money off of, it's literally about something about, hey, consuming less, being thoughtful about the timing of consumption, and that's free. And I think, no one makes money off of that, which is why I think no one ... There's no money interest pushing this into people's faces.

Jason: Well, there was a very interesting documentary on the BBC a few years ago called "The Men Who Made Us Fat", and what they showed was that this idea of eating all the time actually didn't come from science, it came from Cadbury actually, so there was breakfast, lunch, dinner, and Cadbury wasn't making any money because they needed to sell snacks. So they were able to introduce this kind of idea of a healthy snack, and they pushed it and pushed it, and over decades it kind of morphed into this eat all the time, that's good for you.

It's like, okay, when in the history of humanity have we pushed this? Like never, because people are too busy or don't have enough food to eat constantly throughout the day. It doesn't even sound logical. You cannot eat all the time. Every time you eat, you tell the body to store energy. So why would you want to do that? You're trying to let it use energy.

So that's the thing, these commercial interest kind of get into that. But getting back to the fasting in terms of what's really interesting about it. I think this is more towards your kind of demographic, is that there's actually a huge number of benefits about it. so once I started looking into it ...

Now, I'll tell you that when I started using this, I used it from a health and wellness, diabetes, obesity standpoint. I actually didn't start with fasting, I started with low-carb diets. Totally disaster. Nobody did what I told them to do. And part of it was that they actually just didn't understand. They have certain food cultures and so on, and they didn't understand what I was talking about. So I said, I need to do something simpler because I'm not treating people who are on the internet like five hours a day. I'm treating 65 year-old Pilipino grandmothers who really have no idea what I'm talking about and have no email.

I said okay, i need something that's simply, because they need to understand it. Somehow I caught into some conversation with some friends and fasting came up. I thought, wow, that's the dumbest idea ever. That's what my initial reaction is, and that's almost everybody's initial reaction.

Geoff: Uh-huh. I was going to die when I 36-hour fast. How do you even ... Am I literally going to die? How are you doing that?

Jason: Exactly. And people have been pushed out of this idea of fasting for so long, but when you go back in history it's all over the place. Every single major religion has this. So that's why I said, okay, there was nobody doing it ...

Geoff: I mean we've evolved. There was this famine and feast cycles all the time in pre-historic humans. I mean we are animals, right? You got to hunt, you got to starve a little bit, you got to find the next meal.

Jason: There's so many myths around fasting, so what I did was nobody was using it therapeutically at the time so I just kind of made it up as I went. We've been doing it for quite a few years now, so we have a large experience with it. But as we understood more and more about it, there's actually so many interesting things. So you're talking about enhancing performance, and there's actually a cognitive performance I think is totally fascinating because there is a huge advantage to fasting, and you can actually start to look back at some of the studies that people have done on fasting, and you realize that there's a significant advantage. So the Ancient Greeks, this is 2000 years ago, fasted a lot.

So all the hypocrites, Plato, all those guys fasted. No because they needed to lose weight, there is very little obesity and virtually no diabetes at the time. But the reason they fasted was because they understood that it made their cognitive function much, much higher. They're working on a different level, and we still talked about the great Greek thinkers now. And that was their kind of secret sauce, and everybody thinks, "Wow if I don't eat I'm not going to be able to concentrate." It's actually the exact opposite once you start understanding. So think about a time you ate a huge meal like Thanksgiving. It's coming up, right? You ate a huge meal. Well do you feel really mentally sharp? No. You feel sluggish, right?

Geoff: You want to go to sleep.

Michael: Evolved in there. But on the other hand I think a lot of people used the word "hangry" right? On the other hand I think a lot of people use the word "hangry" where they say, "Oh man by the time lunch comes around, I'm hangry.", "I got to eat." Or, "I get a headache.", "I'm in a bad mood." You're telling me I'm not only going to skip lunch, I'm also going to skip breakfast and dinner? No way.

Jason: Yeah that happens if you're on a very carbohydrate diet, that does happen. You get the spikes, you get glucose spikes. So that's why when you eat bacon and eggs, and yeah everybody knows this, if you eat a big protein and fat meal at the beginning of the day, three eggs and three sausage, you're really just not that hungry for that whole morning. You eat a couple of slices of toast and some sugary cereal. Your insulin spikes up, then it spikes down, and then you get that big crash at 10:30am, and then you go, "Oh I need a muffin" right? Or, "I need a donut" right? Then you get that big spike up, then you get that big spike down, and then at lunch you're like, "Oh yeah I could really use some pasta" right? Then you get the big spike up. And people assume that eating is what stops the hunger. So therefore it's like, "Wow good thing I ate that donut" right? Okay well the donut is what may cause the problem where as it's a total spiral.

Geoff: It's a spiral effect again. The death spiral.

Jason: If you look at satiety, for example, things like fat and protein. So if you eat protein, you will stimulate hormones in your body and pretend there's Peptide YY and policystichynine for fat, which are satiety factors. So you eat fat, you eat, you eat protein, your body says, "I'm full." You eat refined carbohydrates, you stimulate none of those satiety factors, you can eat again. So again, think about it for a second.

You've just eaten a huge meal. You went to the buffet, you had a huge meal, right? Now could you sit down and have two pork chops? No, it's like man that's nauseating, right? So the satiety factors are very strong. But if you had this big meal and said, "Oh yeah, do you want some candy or some apple pie, or some highly refined carbohydrates?" Which is what desserts mostly are. Chocolate cake, or whatever. You're like, "Yeah I can do that" right? And we all know that. As kids we called that the second stomach. You have a second stomach for desserts, right? The reason is those highly refined carbohydrates do not stimulate satiety hormones. Therefore you can keep packing them down, right? Without feeling full.

You have to think about it for a second. I used to wonder about this as a kid that you could eat a big meal, which has say 500 calories, and drink water, and be the same fullness as if you ate a big meal and drank, and it had a big thing of coke. Now that coke has 250 calories, 300 calories, or the big gulp of pop, whatever. It's like how come those calories doesn't turn into you feeling more full? Why? Because it's all sugar. There's no satiety hormones that are activated, right? And that's the reason why you can't eat all those refined carbohydrates because they won't make you full. Then you'll eat again. You'll get "hangry" and so on.

Fasting is completely different. In fact, the thing about hunger is actually quite interesting because hunger actually, when you're doing extended fast, hunger first of all comes in waves. It's not constant. So everybody assumes that it's just going to get worse and worse, but in reality what happens is when it passes, it passes. So when lunch time passes and I haven't eaten, I feel like I'm fine until dinner time because it goes in a wave. What you've done in essence is, in fasting, is you've changed the hormones which you don't do with caloric restriction, which is a major difference, but what you're doing is you're basically feeding your body with your body fat, right? So imagine if you're fasting for say seven days, like Jimmy Mort in 21 days, my co-author on this other book The Complete Guide to Fasting. What he's doing is his body is actually eating breakfast, lunch, and dinner of fat, right? And after about three, four days, the hunger actually goes down.

So this is the one thing that we see. We've treated a thousand patients. And the one thing they're always surprised at is they said, "I thought I could never do this because I thought I would be super hungry all the time. I actually can't eat very much anymore, and then I get full." I'm like, "Perfect. That is exactly what we want." And he says "I think my stomach shrunk." I'm like, "Well your stomach didn't actually physically shrink, but that's what it feels like because now you're resetting your body set weight downwards and you're actually working with your body to lose weight. Now your body wants to be at that lower weight." Which is great. So now as soon as you get full, you get full and you can't eat anymore, which is great because before if your body weight is high, you want to keep eating and you're using will power to stop yourself, but that doesn't get you very far.

Geoff: I think you brought up a couple of good notions, and I want to bring us back to from the side track, back to the cognitive enhancement part because I think we're going to a very interesting train of thought there. And you're mentioning breaking out fat as an energy source. So a lot of the interesting ... I'm curious to get your thoughts around what you think the mechanisms are for increasing cognitive function while fasting. Is that the ketone to metabolism?

Jason: I think it certain does have a lot to do with the ketones, but I think that there's actually more to it than that. In terms of cognitive ability, I think that there's actually two parts which I think are interesting which I'll try and touch on, is one the cognitive boost, and two is Alzheimer's disease which I think the data coming out of that totally fascinating. So in terms of-

Michael: I've heard of it like that. People almost call Alzheimer's "Diabetes Type 3". I think you might be touching upon some of this.

Jason: Yeah, and that's kind of the idea. And also, remind me if I don't talk about it via autophagy which is again a super hot topic. So what happens during fasting is that your body has very little glucose, right? Because you're not eating sugar. So you switch over your metabolism to a fat metabolism. Your brain uses a lot of glucose and what's a huge, huge myth that's always perpetuating is that your body needs 130 grams of carbohydrates and your brain needs 130, otherwise it'll shut down, right? It's like okay, right. So if I don't eat for 24 hours, I should be a blubbering idiot, right? That doesn't happen because what happens is that after your glucose stores run out, your body produces ketones which could supply up to 75% of the energy needs of the brain. That's why you don't actually need 130 grams of carbohydrates a day.

It's actually sort of true, you just don't need to eat 130 grams of carbohydrates a day. Your body will provide the glucose that it needs. So it's a process called gluconeogenesis, it will actually manufacture glucose for your brain. The rest of it runs on-

Geoff: Breaking down protein, right? Breaking down-

Jason: Breaking down proteins and breaking down fat. You got to remember that fat is called a triglyceride, which is a glycerol backbone attached to the three fatty acids. You break the three fatty acids off and your muscles and so on can use those. But the glycerol gets turned into glucose which goes to the brain. But you can't supply the entire energy needs of the brain by glucose. There's too much for that, so you produce from the fat ketone bodies which cross blood brain barrier go in. And it's thought-

Geoff: And that happens in the liver, just to help people follow along so that fatty acids that break off get turned into ketone bodies, beta hydroxy beauterates, and a couple of other minor ketone bodies. But BHB is a primary one. It's in the liver, and as you mentioned is permeable across the blood brain barrier, and it ends up being this fuel for the brain.

**Jason: Yeah and it's thought that a lot of the brain actually functions a lot, at a lot higher level on ketones. So some people ... If you look back in history, there is a fascinating book called Unbroken, by Laura Hillenbrach which is about American prisoners of war in Japan during World War Two. In it, as I was reading it, I was totally fascinated because they say that they noticed these prisoners were doing absolutely incredible mental things. One guy would read a book entirely from memory, and another guy learned Norwegian in a week, and they were all very blasé about it because they're like, "Oh yeah it's the astonishing mental clarity of starvation." I'm like, "Whoa! This is incredible because starvation is uncontrolled fasting." Fasting is a controlled version of pot. Eating starvation is the uncontrolled version of not eating. I'm like, "How is it that these people, first of all they face it everyday so they kind of knew what was going on but we forgotten that." You can read these accounts through history where people have realized that when you don't eat, your brain goes into hyper drive, right? It's working at such an incredible level that you cannot even comprehend because the ketones are there and it's working so well.

So now what people have done is looked at caloric restriction, which is kind of a watered down version of fasting, but that's what they do in laboratories and looked at memory and you can clearly see that when you restrict calories, memory goes way up. And the other thing that's really interesting in terms of Alzheimer's-

Michael: I haven't seen that in healthy human models yet. Usually the cognition is in rat models, right? But I think they're trying to replicate-

Jason: There's a lot of rat ones, but there's a few small ones in humans as well. And this is where a lot of the things come out. So Alzheimer's disease is a huge problem, right? And Alzheimer's disease is caused by these abnormal proteins that kind of gum up the brain, right? So what you stimulate during fasting is a process called autophagy, okay? And this is a super hot topic because one of the key researchers of autophagy won the 2016 Nobel Prize for medicine.

So what is autophagy? Autophagy is a process where you body breaks down these junky old proteins and burns them for sugar, right? And everybody thinks that getting rid of protein is bad, but it's actually really good because if you want to ... If you have a disease like the Alzheimer's disease example, which is all this excessive protein that's gumming up your brain, if you could do fasting, and all of a sudden encourage your body to get ride of all this excess protein, you are going to increase the ability of your brain to work. So you see that in small human trials where cognition increases, memory increases, all the cognitive function increases, you can see it back in history where people have these amazing things. The Ancient Greeks for example, there are stories of them forcing people to fast. So the head philosopher, whoever. I can't remember if it's Plato or whatever, he would force his students to fast for 40 days or something like that. Then he's like, "Come back when you've done that." Right? Because you're too dumb otherwise. That was the implication, which I think is just an amazing story.

So here's the super boost to mental capacity that's available for free. That's insane. And people have tried to shortcut this, right? With exogenous ketones, right? So people sell these exogenous ketones. But it doesn't really work because if you still have glucose floating around in your brain, your brain may just say, "Hey, why don't I just use this glucose. I'm used to it anyway. There's ketones running around, but hey I don't know if it's back there." I mean there's anecdotal evidence everywhere.

Geoff: Yeah, but I think I've seen some data that show that if you have high enough levels of exogenous ketones, you can actually ... When I actually tried some ketone esters, I was running a blood glucose monitor, and after 30 minutes, it dropped my blood glucose levels from 6.7 per milliliters to 5. So that keto had rushed as some people would say. So I think there's a lot of different types of exogenous ketones and I think it can be it's own separate conversation on the ketone salts, ketone precursors like MCT oils, or ketone esters are a little bit more pure. But I think ...

Jason: Well one of the fascinating things is that ... So they're looking at ketones in ... Dominic Agostino who does a lot of the research into that.

Geoff Right.

Jason: He does it for the department of defense, right? Because they're looking for physical enhancement and cognitive enhancement. We haven't talked about the physical enhancement. So what's interesting is that it doesn't even make any sense. If you're sending soldiers into combat and packing them some exogenous ketones, here you go, why don't you just fast them? They have a month worth of food carried on their own body, right? If they're not eating, then they're going to start burning that fat, they're going to have mega ketones. They're going to have this cognitive boost, this physical boost, and that's amazing, and it's all for free and you don't have to weigh them down with exogenous ketones, or even food, right? That's amazing.

So now think about the astronauts going to Mars. This big thing about going to Mars, right? "Oh how are we going to do the food?" Why don't you just not have them eat, right? If you don't eat ... So a fast of one day burns about a half a pound of fat roughly. So if you've got about 30 pounds overweight, and most of us have that amount of fat, right? So an ultra lean person is about 10% fat. These are the marathon runners that look like little sticks, right? They're about 10% body fat, 5 to 10. So if you're 150 pounds and you're 10% body fat, that's 15 pounds of fat. Most of us are nowhere close that, right?

Geoff: Being devils advocate here. I mean glucose is really beneficial for power, right? Like basically bursting. So if you just literally have no ... Probably something more optimal like cycling with some glucose, and also fasting in certain areas. I imagine that if you're constantly in a fasted state, your muscles ... I mean glucose is still a very powerful, readily available energy source, right?

Jason: And it depends, right? So if you go from glucose to fat, there's actually a period of adaptation called keto-adaptation which takes a couple of weeks, but you got to realize that people at the very highest levels are already there. So Frum, who won the Tour de France is all taking ketogenic stuff, right? LeBron James talking super low carb, right? Kobe Bryant, right? Who prolonged his career. They're all doing it, right? And these are guys whose livelihood depends on being at peak athletic performance. So other guys like Sammy Heineken who rode from ... He and his wife rowed from I think San Francisco to Hawaii, right? They all did training in the fasted state. So you got to realize that fasting actually provides a physical boost as well. So this is kind of another huge, huge area that people are getting into. So if you look at national teams, rugby, cricket, they're all going low carb. Why? Because the thing about training in the fasted state is that you have to look at the hormonal adaptations.

So what happens is that your neural adrenaline goes up, your sympathetic system goes up, it's a general activation, and growth goes up. Those are also called counter-regulatory hormones. They counter the effect of insulin. Insulin makes your blood-glucose goes down, this makes your blood-glucose goes up. So if you're in the fasted state, you want your body to start pulling out some of that glucose putting into the blood. So those are the counter-regulatory hormones. So your adrenaline level goes up ... Neural adrenaline to be specific, and your growth hormone goes up. The more adrenaline goes means you have a lot of energy. That's what people find. They have more energy which means you can train harder. Then your growth hormone is up so that when you start eating again, you recover faster. That's a huge advantage for any athlete. If you could train harder-

Geoff: I would add that the oxidative stress of ketosis is less than that of breaking down glucose, right? If that because you're not producing lactic acid buildup, that experience of feeling the burn is also less present.

Jason: And again hitting the wall which is bonking or whatever, that happens when your body is used to using glucose, and it runs out of glucose, right? But you have almost unlimited supplies of fat. So if you train your body to burn fat, you almost cannot hit the wall, or bonk or whatever in the ultra endurance. The ultra endurance guys have all gone over to super low carb. You can actually measure. If you do muscle biopsies, you can actually measure that the gene products that are involved in fatty acid oxidation increases as you go. And again, you can look at things like V02's.

So if you do four days of fasting, you actually see no decrease in V02 which means that your capacity to do exercise is actually higher than when you started fasting. Four days of no food, and your resting metabolic rate, and this is super important for weight loss, is higher. Remember when I said that when you try and cut your calories, 500 calories a day, your resting metabolic rate or your BMR (Basal metabolic rate) goes down. It does not do that in fasting, and that's why people can keep their weight off with fasting because you don't have that disadvantage.

So the Biggest Loser, for example, did this. They used a caloric reduction model, right? And then what they did was they measured their metabolic rate. At the end of it, they're burning 780 calories a day less, right? That's a huge disadvantage. That means simply to stay still you have to eat 700+ calories less per day, and that's the reason everybody fails is because your metabolic rate slows down, and they call this starvation mode. So what's ironic is that caloric reduction puts you into starvation mode. But doesn't put you into starvation mode is actual starvation because the controlled version, fasting ... So four days of no food, you're at 10% higher metabolic rate. So you're feeling good. You're generating body heat, your brain is working, and your V02 is 10% higher. You have as much or more exercise capacity than you did before. Once you get through that adaptation phase then the muscles start using it too because glucose is a good source of energy but the muscle glycogen is carried separately from the liver glycogen.

So you can still use it on a short term, but again with the lactic acid with the hitting the wall, there's all these advantages with fasting/low carb, which is getting you over to burning a sort of fatty acids like burning fat versus burning sugar. There's just a huge advantage.

Geoff: So I'm curious to dive into the low carb ... A straight ketogenic diet is 70% calorie from fat, 15/15 from carb and protein. And I think that seems like a very ... Realistically that's very hard to maintain. 70% from fat is super hard, and some of our community members....they're hardcore keto followers. I'm thinking of one of our members, her name is Ayumi and she's a software engineer, and an aspiring DJ that goes by the name of Keto God. That's literally her DJ name. She brings sticks of butter to breakfast so she can get enough fat calories. Obviously there's interesting data that show that hey we're placing a ton of saturated fats, as in animal fat, isn't actually great for heart health. You probably want to supplement with at least poly-unsaturated fats, etc. For those who are trying to eke out performance benefits, as you mentioned, how would one do that realistically? Or is it just like, "Hey you got to be crazy disciplined now."?

Jason: No you don't have to because the thing is that the fasting is not nearly as hard as people say. So rather than bringing sticks of butter, why don't you just not eat, right? If you don't eat, if you fast, what happens? Your body switches to burning body fat. So, good, right? Instead of burning that butter that you brought in, and eating butter is super gross, right? Well not super gross, it's a little bit gross. Why don't you just eat body fat, right? It's easy. You drink your coffee, drink your green tea, drink whatever, stay hydrated and let your body eat the body fat. That's 100% fat, right? Ketones will go up. It's a short way to get into ketosis, and that means you can come in and out of ketosis whenever you want because you can always bring it on, you can bring it off. There's so many advantages to the fasting, right? That's why fasting is not the same as spreading it out over 24 hours, right?

So some days, for instance, I'll eat 250 calories, but the way you have to think of it is that, "Oh hey I ate 500 calories of body fat at breakfast. I ate 700, 800 calories of body fat for lunch, and I'm-

Geoff: It's interesting to look at it, yeah.

Jason: "... 350 of dinner." So what the hell is wrong with that, right? But everybody is saying, "Oh 250, you're going to go into starvation!" No I'm not. I'm burning body fat because I want to, and now hey that's like a 90% fat diet. Good thing most of it is body fat, right? So then you start to get into the ketosis again, and if you don't want to do that because you like to eat donuts, then you can. You'll break it, but next week you can go back in and say, "Hey guess what? I'm going back, I'm fasting again. I'm going to start burning all that body fat I put on because I ate all those donuts." Right? So it's flexible, right? There's so many advantages to the fasting because-

Geoff: As opposed to trying to keep a ketogenic diet by eating constantly.

Jason: Yeah. It's hard.

Geoff: I think the big thing that we've seen is ... Yeah. Basically be really disciplined for short bursts of time where will power is limited, focus that on controlled sets of time, then you can have breaks and you can get back onto it as opposed to be disciplined forever.

Jason: Yeah the thing is that the fasting is completely different than any other diet. It's almost the anti-diet, right? Because it's not making things more complicated. All our lives are complicated. It's making things simple, right? You don't have think what you're going to eat. You don't have to think, "Oh what's your macros?" You don't have to think, "Oh I have to go shopping. I have to get this-

Geoff: Just don't eat.

Jason: Just don't eat, right? There's no shopping. There's no food cost. There's no cleaning up. Oh you get an extra 45 minutes because you didn't lunch. Oh hey you get an extra half and hour because you didn't eat breakfast. Oh hey, you're saving time, you're saving money, it's amazing, right? That's amazing! And you're going to get the cognitive boost, you're going to get the physical boost, you can use it when you want to. Hey you're on vacation, you're not going to be the guy who never eats dessert, right? You're not going to be the guy at the wedding saying, "Oh no I can't eat wedding cake." Right? You can do because you know that next week you can go back in and fast and burn all that off, right? Because the whole idea of fasting is not something you're going to do, it's something that you're going to not do, right? So it's the opposite of everything. Ketogenic diets are complex. That was the problem I had when I tried to put people on low carb diets. It's adding complexity to their lives. I'm trying to free people from that.

You realize when you do it for a while the tyranny of the breakfast, lunch, dinner. And even worse if you have to throw in all your snacks. "Oh what am I going to have for breakfast?" "I'm not even hungry." "Oh but you got to eat breakfast." I'm like, "Well eating when you're not hungry is not a winning strategy." Right? Grab your coffee and go. That's what I do almost-

Geoff: Hey one question I want to make sure we touched on during this conversation was just there's different hormonal systems from men to women, and I think that it's a common question that we get from women is, "Is fasting okay for me? It's a different hormonal balance. I don't want to do this, it's not good for me personally." Can you comment a bit on the difference in effect there?

Michael: Yeah I think we've gotten feedback where, "Hey longer fast for women." People start losing their cycles, getting their cycles off balance.

Jason: Yeah. First of all, fasting for women is fine. We have treated hundreds and hundreds of women, and there's no problem. There's no problem with women and fasting. Again, you go back into human history, people have been fasting for at least 5000 years, right? Look at the Muslims, Ramadan, look at the Buddhists and all the Hindus, and Mormons, all these people who fast. Women do it too, and they have no problem. Because the thing is that the hormone that is involved in eating predominantly is insulin, insulin-glucagon. The difference between men and women is sex hormones, estrogens. So yes there is a point. There is a lower point when you fall below a certain body fat percentage that you will lose your cycles, right? But after that it's no problem. In fact some of the people who are on the overweight side, they get this polycystic ovarian syndrome where they're improved.

So it's just a giant myth, and it got very popular because one person wrote a blog post about it, talked about a bunch of rat studies, obviously had never fasted herself or never supervised people fasting and said, "Oh it's really bad." And then Mark Sissen re-posted that and everybody in the world thinks that women shouldn't fast. I'm like, "Okay well what do you think happened in 1800? Women who didn't have anything to eat or fasted because of religious purposes all of a sudden they didn't have children anymore?"

Geoff: Maybe the argument is that maybe their fertility goes down during that fasting state, right? The body conserves like, "Hey there's lots of fat in our bodies now, we shouldn't have babies so we're going to shut down."

Jason: If you're at that lower level, definitely. So if your body mass index is below 20, I'd say you shouldn't fast. Obviously. If your weight is too low, you should not fast. If you're malnourished, you shouldn't fast. That's just common sense, right? But if your Body Mass Index is 30, and your 50 pounds overweight, and you're a woman, yes, it's okay.

Michael: How about if you're a healthy woman who wants to get some of the enhancement aspects?

Jason: Yeah, again it's no problem because the thing is that what you don't want to do is try and mix the fasting with caloric restriction. Your body will tell you what you need. So if you don't eat for 24 hours, yes you may eat 2000 calories. You may eat your full days worth. You got to listen to your body and eat it. You don't want to say, "Whoa, now I want to cut down this much to 500 calories so I lose weight." You don't want to mix the two up. It's not about calories. So you got to listen to your body because you can eat the same number of calories. There's still a difference in terms of insulin sensitivity and they've done these studies where they've matched the calorie for calorie that had one group do it as a steady reduction, and one was an intermittent reduction, and there are big differences in insulin and insulin sensitivity. So there's still benefits to doing it even if you match it calorie for calorie.

So that's what's important. That's what I'm saying. The frequency of how you eat still makes a difference. You can still eat the same amount, but change the timing of it and get those benefits. And people are kind of crazy because it's like ... When I ask people to do fasting blood work, they fast. When I ask people to do it for routine colonoscopies, everybody over the age of 55 is supposed to get a colonoscopy, fast for either 24 or 48 hours before to get rid of all the stool so that people can see. Nobody ever raises a fuss. "Oh I'm a woman! I can't fast!" I'm like, "Yes. Everybody does that!" Or you do an ultrasound and they tell you not to eat, or you go in for an operation and you don't eat, you're fasting! That's it.

Everybody has got this in their heads that this is such a crazy, crazy thing. But remember, the word itself "breakfast", "break" "fast" means that fasting is a part of everyday life. It's normal. It's only the flip side of eating. And you want your eating and your fasting to be balanced, right? What we've done is we put people into this state where we think we have to be in the fed state constantly, and people are sick because of it. So you got to balance it. I'm not saying you should fast all the time, like anorexic or anorexic nervosa, but you got to make sure they're balanced. So if you're too far one way into the fed state, then you got to bring it back.

Geoff: Good. I think that's good clarity and hopefully we want to give you the platform, keep spreading that good knowledge and really fundamental science. I think that's one of the interesting things about this whole space, right? It's a lot of different cycles of thinking every five years. It's like really focus on things that we believe come from true fundamental science.

Jason: Yeah and I think it is coming around. We spent so long trying to kind of suppress this idea that fasting can be good. But if you think about it-

Geoff: Yeah I mean what do you think about the whole thing? I feel like we're at a tipping point. I think from the New York Times article, really opening up the sugar lobby as pushing different health associations, doctor groups, I feel like we're at a tipping point. We're just seeing the growth of the we fast-

Michael: I think fasting is the new exercise. I feel like it's at the tipping point. I'm sure our listeners think it's a tipping point. What do you think from your ... sort of last question here as I'm sensitive to your time, do you feel like it's a tide shift?

Jason: I think so, and I think that you're right. It's a grass roots movement because nobody makes money for it, but it's about the people trying to take power over their own health back into their own hands, right? Because what they're saying is that I can take care of my weight problem, I can take care of this problem, that problem naturally without paying somebody a lot of money, or taking this drug or whatever. Because what people have recognized over the millennia is that fasting is not something that's harmful, and it's not really a treatment for illness, what is is really a treatment of wellness. This is the way you stay well, and it used to be called that, a detox, a cleanse, that's exactly what it was, right? What you did was you fasted, and you cleaned your body out of all that excess glucose that was killing you, all the excess fat that was killing you, all that junky protein that is gumming up your brain and gumming up your system. Then as you fast your human growth hormone goes up and your body starts to lay down new cells.

So now what you've got is a real anti-aging process that is amazing and free. It feels like that people are starting to understand that the little bit more ... That yes this is something that we can actually do, like your group the We Fast group is amazing because what you do in this sort of groups is your able to help each other get through it, because there are problems that come up. Let's be honest there's hunger pains, and there's problems with feeling-

Michael: Yeah people aren't used to it, yeah.

Jason: You're not used to it. You'd be getting the headaches, for example, then you'd go talk to your friend and your friend says you're crazy. Then you talk to your doctor, and your doctor said, "Stop it right now!" You talk to your dietician and she'd say, "Oh you're going into starvation mode! Stop it right now!" And then you'd go, "Oh I give up." Right? But you come to a group and they say, "Hey, no problem. I had that the other day. This is what you do." Right? And that's the power of connecting people and having that knowledge you can share that's peer to peer support which is really important in a group like yours. I actually think it's fantastic. And that's what you need to do because there's so many benefits, we didn't even talk about the cancer benefits, right? People talk, and there's a huge literature-

Geoff: The metabolic theory on cancer, right?

Jason: The metabolic theory on cancer and also the autophagy part of things which is clearing out those junky cells, and it truly is a way to clean out your body, and if you never do. So the three most influential people in the history of the world, Jesus Christ, the Prophet Mohammed, and Buddha, probably only agreed on one thing which is the power of fasting. And they don't do it because they want to kill off their parishioners, right? They do it because there's something unique and intrinsically good about the fast.

Geoff: I think we're here to say anything for growing. I appreciate that last nugget of morsel of food for thought there. I think that leaves a great framework of how to think about how fasting is not some crazy new age thing, this is almost the most original fundamental truth that different religions, and really just how we evolved as humans. And we have to have you back on the talk about a couple of these other topics that you've mentioned, cancer, and also would love to talk about the second part of obesity ... I guess the second installment, The Full Fasting Guide.

Jason: Yeah for sure. That'd be great.

After the show...

Geoff: That was an awesome conversation with Dr. Jason Fung. I'm sure we'll all have some food to churn on there, and if you guys have any questions for him, send them our way. We love your questions. One of our most recent and the most dedicated We Fast members Dr. Manuel Lam has given us a ton of questions and we love that. So I know more of you out there are listening. Send us a bunch of questions for the second time we bring Dr. Fung on the program here.

See you next time thinkers!

Emails worth reading.

Once a week, we'll send you the most compelling research, stories and updates from the world of human enhancement.

HVMN Co-founders Michael Brandt and Geoffrey Woo