The Truth with Dr. Jason Fung

all the time. We've gotten into even what's going on with ozimpic and Menjaro and all this stuff, but intermittent fasting has been kind of above reproach. It's not even considered a fad by many. It's just been this kind of steadfast dietary plan that to this point has been

really bulletproof. But then, all of a sudden, from very credible sources, including the American Heart Association, a study of over twenty eight thousand adults finds that those who followed an eight hour time restricted eating schedule i e. This is you know, intermittent fasting, have a ninety one percent higher risk of death from cardiovascular disease. Now, when you hear those numbers, you think, my God, and there's more

to that that we'll talk about in this study. But I immediately started scouring the internet, got deep into this rabbit hole and I know what I don't know, and that's important in this world to know when you have reached your limit, hit that ceiling, and you need to go to an expert. I have found an expert joining me now on the most dramatic podcast ever is doctor Jason Fung. Why is he an expert? Well, not only is he a doctor, but he literally wrote a book,

The Complete Guide to Fasting. So if there is anybody in this world, doctor Jason Fung, I think you are more than qualified to get into what we just read about intermittent fasting. Welcome to the show.

So in science we have to, you know, very carefully distinguish between what when two things are correlated and when one thing causes the other, because you know, two things can be correlated, but they don't cause one another's. So for example, if you look at people with gray hair versus people without gray hair, the risk of dyeing is probably like ten times. Why because the people with gray hair are older, So you can't compare the two groups

because they're very unequal. However, there's a very strong correlation between the grayness of your hair and how much your risk of dyeing is, or the wrinkles on your face and how you know your risk of dying. But obviously it doesn't mean that you should dye your hair black and that will reduce your risk, and it doesn't mean that you should get you know, botox and that will

reduce your risk. It's completely irrelevant. So those two things are correlated because they're caused by a third external factor. That is the age is the confounder here. So if you're older, you have gray hair. If you're older, your risk of dying is higher. But one doesn't cause the other. So that's very very important to keep in mind. So the point of this study was that they correlated two groups.

One group that was, you know, sort of fasting. They weren't fasting, they were not eating over a period of time compared to those that did. And they said, well, one group has a higher risk, but that doesn't mean that one cause the other. And what happens is that people took that to mean one cause the other. And that's where it gets very dangerous because it's in medicine.

There's something called the healthy user bias, which means that if you look at two groups of people that are unequal, then of course you're going to find a risk that may go up. For example, we did this when we looked at hormone replacement therapy. So if you look at women who took hormone replacement therapy, this is twenty years ago when we put virtually, you know, every postmenopausal woman on hormone replacement therapy. My mom was on it, all

her friends were on it, everybody was on it. And they did this because there's a strong correlation between I mean, the women who took hormone replacement therapy and the risk of heart disease was about fifty percent lower. So people took this and said, well, that proves that taking it reduces your heart risk, which is the same as saying dyeing your hair black reduces your risk of dying. It doesn't. It turns out that the group that took hormone replacement

therapy was much healthier in many other ways. They looked after themselves, they saw their doctor, they got their blood work. So when they actually did the study, they found that, in fact, taking hormone replacement doesn't reduce your risk at all. Zero. It had zero benefits. So we literally put millions of women on based on this flawed understanding. And by the way, this understanding that correlation is not causation, That is that two things are correlated does not mean that one causes

the other. That sort of very basic, sort of first year you know, statistics sort of thing. Everybody should know this, but we we spent you know, hundreds of millions of dollars to put women on women, millions of women on needless drugs. We did the same thing with multi vitamins, for example. So people said, well, if you take a multivitamin, there's it's correlated with the risk of dying that is lower. But when they actually gave people multi vitamins, it didn't

lower the risk of dying. Same thing. Healthy people who took multivitamins were healthier in many other ways. So you have to look at this idea that okay, eating you know, not eating for sixteen hours a day. Were those people different than the people who were eating, you know, six times a day, that kind of thing. And what I have to understand is that the database that they used from two thousand and three to two thousand and eighteen,

at that point, nobody was doing intermittent fasting. So if you look at Google trends, for example, and I wrote about this, you know, if you look at Google trends, there was zero interest. In two thousand and four, twenty ten, twenty fifteen, nobody was interested in fasting for either health reasons or weight loss. It was considered the stupidest thing you could do. I know, because I was writing all

about it, and I got all kinds of flag. It wasn't until I published my book The Obesity Code and then The Complete Guide to Fasting that it started to go up because I pointed out that, hey, there's nothing wrong with intermittent fasting. But if you think about the group that was not eating during the period for ninety percent of their database, those people were different because those people were probably people who had, you know, drug problems.

They might have alcoholism, they might be smokers. They might not be eating because they had other illnesses such as cancer. So any of those things could have caused this seeming this correlation, but it doesn't mean that one caused the other. So the entire premise of the study was flawed because they were saying, well, people were fasting back in two thousand and three for weight loss, but nobody was. The interest in fasting was abysmal when I started writing about

in twenty thirteen, twenty fourteen. I mean, people thought it was the craziest thing they'd ever heard of, Like, you have to eat. Everybody knew you had to.

sort of errors in interpretation. The study is the study, the correlation is the correlation, but the way you interpret it that one causes the other is so erroneous, like such a basic Like if anybody said that to me above high school, I'd say, you're an idiot.

could have been on a high protein diet. Well, yeah, you're probably going to be healthier than me. And they didn't take into account. They were saying, like you know, cancer and diabetics had a higher risk. Well, no kidding, like you said, of course they did.

know about, short of smoking. So it's worse than diabetes. It's worse than not exorc say, it's worse than being overweight. It's worse than you know, living next to you know, power lines. It is worse than taking all kinds of carcinogens. So this thing where you eat at nine am and eat at five to five pm, which is not that bad, is this horrible, horrible risk factor that somehow, you know, evaded us. And you have to realize that fasting is

not a new idea. Okay, people have been fasting for thousands of years, right, so if there was a problem with fasting, we probably should have known about it. And the other thing is that in the same study they showed that if you fast for eight to ten hours, that is, say you eat breakfast at nine am and dinner at seven pm, your risk of heart disease went

up by sixty one percent, sixty six percent. That's ridiculous, Like that's called every single person in the nineteen seventies eight, like they didn't eat snacks after dinner, so they might eat at nine am to seven pm. That's just a normal day. Literally millions of people did that. The thing is that it's click baity, right, so of course it got in the newspaper and so on. And what bothers me is that then these sort of elementary mistakes where

people are interpreting a study. You know, basically they're saying the equivalent of get botox. You know, they'll save your life, right, It's like, no, it won't. Just getting you rid of your wrinkles doesn't do anything for your buy your hair, it'll save your life. It won't. So they're making this sort of elementary mistake, but they're scaring people. It's fear mongering. It's scare mongering from people away who from something that

could potentially help them. I'm not saying it's the right answer for everybody, but clearly some people have benefited tremendously from doing intermitt and fasting, and those people might get scared away and therefore actually be harmed from this sort of awful sort of interpretation mistake, sort of basic elementary mistake of correlation and causation.

a good thing. What do you see are the major benefits of fasting?

But the thing is that if you do intermitted fasting, some people will be helped because obviously, if you don't eat, your body will burn off some of that glucose, and if it burns off the glucose, then your blood glucose goes down and you don't need the medications or you can even completely reverse your type two diabetes. So the idea is very simple. Intermint fasting is not heard to understand. Your body can store food energy, which is calories. Right, eat,

You're going to store calories. That's what you do. It's a good thing you can otherwise you die in your sleep every single night. Right, We're not like moles you have to eat like every one hour or they die sort of thing. We can store energy. So your body stores energy, and it stores it in the form of sugar, which is glucose and fat body fat. Right, that's what it's there for. When you don't eat, that is fasting.

That's the time that your body now says, oh, I'm going to take those calories that I store and pull them out of storage, because that's the logical thing to do. That's all it is. That's all fasting is you store energy like body fat for a reason. It's not there for looks. It's there for you as a source of energy when you don't eat. If you never fast, if you never don't eat, how do you expect to burn

that body fat or that blood glucose. You can't. It's actually impossible because if you're eating, you're telling your body to store energy. It's only when you don't eat that you use the energy. In other words, if you're eating all the time, which is the big fad you know in this eighties, nineties, two thousands, well you're not giving your body a chance to burn it. So of course you're gonna of course you're going to gain weight, right,

there's no other way. So if you want to lose weight, all you have to do is to extend the period to give your body a break from the eating and let your body burn off what you store. And it's completely natural. There's nothing wrong with it. Our bodies have adaptmed. That is, if you think back to cave men cave women,

it's winter, there's nothing to eat. Well, when we have all died by now, if fasting was really this bad for you, right, our bodies like why do we think our bodies are so incredibly stupid that we have to like figure out Look at the watch. Right, as a caveman, you don't have a watch, but you're going to figure out that you need to start stuffing them up, which you don't have. Of course, you have to go hunt, you know, a beaver or something to get food because otherwise,

if you don't eat, you're gonna die. It's like, uh no, your body has started away. That's the entire point. It's part of a natural cycle of feeding and fasting. That's all it is. That's why we have the word break fast. It's the meal that breaks your fast, but you can't break it if you're not fasting. So the whole point is that fasting is not a fat like everybody says it's this big fat. It's like it's been around for

thousands of years. It's mentioned in every major religious text, so we know that people have been doing it for two three thousand years. And in that time, where people have talked about fasting, it's always in a healthy connotation. That is, they talk about it as a detox or a clensing or a purification or something like that. So the whole thing is that everybody thought fasting was really good for you, and then until the eighties and then they thought it was really bad for you. But you know,

it's really just part of this natural cycle. Feeding all the times bad, Fasting all the time is bad.

probably true. You're a nephrologist, which is a specializing in kidneys and the renal glands, So there you go. I also learned something today about nephrology. Perfect, but doctor, thank you so much for your knowledge. Truly appreciate it.