Ep. 332 Bio-individuality and Fasting: Personalized Approaches to Metabolic Health with Dr. Jason Fung

Your trusted source for nutrition, wellness, and mindset for thriving health.

I am delighted to reconnect with Dr. Jason Fung today. We last connected in October 2020 for Episode 121.

Dr. Fung is a nephrologist and a prominent figure in the intermittent fasting and low-carb space. He has made significant contributions as a founding member of The Fasting Method with his evidence-based guidance on weight loss and blood glucose management through low-carb diets and intermittent fasting. He has written several books, including The Obesity Code, The Complete Guide to Fasting, The Diabetes Code, and The Cancer Code.

In our discussion today, we look at the forecast for metabolic health in 2024, exploring how the growth of the diabetes population relates to the effects of the pandemic and addressing the conflict of interest with organizations like the ADA and registered dieticians. Dr. Fung shares some of his biggest frustrations, including the shallow and myopic thinking amongst those focusing on calories in and calories out, and we get into various facets of metabolic health, from the nuanced influences of gender, puberty, perimenopause, and menopause to hedonistic eating, sarcopenia, bio-individuality, and therapeutic fasting. Dr. Fung also shares his perspective on GLP-1s, shiftwork, supplements, and more.

Join us for valuable insights on various aspects of metabolic health and how they impact our well-being.

“A lot of people these days may be very magnesium deficient because the soil we grow our foods in has become very depleted in magnesium.”

– Dr. Jason Fung


  • How the influence of food companies has led dieticians and diabetes associations to focus on moderation instead of a balanced diet
  • Dr. Fung shares his frustration with the lack of progress in addressing the diabetes issue
  • How hormones impact weight gain and hunger
  • Why does focusing on calories in and out not provide the solution to weight loss?
  • How intermittent fasting can help to control hormonal issues
  • How middle-aged women need to find balance when fasting to maintain muscle mass and avoid sarcopenia
  • How intermittent fasting can lead to increased strength despite losing muscle mass 
  • What causes shift workers to gain weight?
  • The potential drawbacks of using GLP-1 drugs for weight loss
  • Why magnesium deficiency is a common problem in modern society

Connect with Cynthia Thurlow

Connect with Dr. Jason Fung

Previous Episode Featuring Dr. Fung

Ep. 121 – The Truth About Diabetes, Kidney Disease and Insulin Resistance with Dr. Jason Fung


Cynthia Thurlow: [00:00:02] Welcome to Everyday Wellness podcast. I’m your host, Nurse Practitioner, Cynthia Thurlow. This podcast is designed to educate, empower, and inspire you to achieve your health and wellness goals. My goal and intent is to provide you with the best content and conversations from leaders in the health and wellness industry each week and impact over a million lives.

[00:00:30] Today, I had the honor of reconnecting with Dr. Jason Fung. We last connected in October of 2020 for the podcast Episode 121. And if you’re not familiarized with Dr. Fung, he is one of the leading voices in the intermittent fasting low-carb space. He is also a nephrologist and one of the founding members of the fasting method to provide evidence-based advice for weight loss and managing blood glucose, focusing on low-carb diets and intermittent fasting. He is also the author of the Obesity Code, The Complete Guide to fasting, The Diabetes Code, and Cancer Code.

[00:01:05] Today, we spoke at great length about the forecast for metabolic health in 2024, the growth of the diabetes population relative to the impact of the pandemic, conflict of interest with organizations like the ADA as well as registered dietitians, some of his biggest pet peeves, including the myopic focus on calories in, calories out, which he believes to be very shallow thinking as there’s so much that drives behavior around food, the impact of metabolic health and gender, the impact of puberty, perimenopause, and menopause as well as andropause, hedonistic eating, the role of sarcopenia, bio individuality and therapeutic fasting, his thoughts on GLP-1s, shift work, supplements and more. I know you will love this conversation as much as I did recording it.

[00:02:05] Dr. Fung, such an honor and a privilege to have you back on the podcast. Welcome again.

Dr. Jason Fung: [00:02:09] Thanks. Great to be here.

Cynthia Thurlow: [00:02:11] Yeah. I thought it would be fun to talk about the metabolic health forecast for 2024. I know some of the recent statistics that I’m sure you’re very familiarized with is that as one example, the diabetic population is expected to grow 3.2% annually. And right now, there are over 38.4 million Americans with diabetes, which is 11% of the population. But even more concerning than that is that there are 8.7 million Americans who are currently undiagnosed and that’s 22.8% of the population and those statistics come from the CDC and they are readily available online. What are your thoughts, are you thinking that we are heading in the right direction as a population or do you think we are still navigating poor metabolic health to a really significant rate?

Dr. Jason Fung: [00:03:01] Personally, I actually think we’ll continue to see some worsening. If you look at type 2 diabetes, which is one of the big problems, you see that it lags the obesity epidemic. So as that gets worse, then diabetes gets worse, but it doesn’t sort of turn around right away. The other thing is that we know that there are interventions that work very well for type 2 diabetes in terms of reversal and so on. So, there’s been a number of studies. So, intermittent fasting is one of those that has shown a lot of benefit and it’s not very difficult to understand. If you don’t eat, your body will use some of that glucose that is in excess.

[00:03:41] So, the other thing, of course, is low-carbohydrate diets. Again, there’re three macronutrients, carbs, proteins, and fats. Carbs are glucose. That’s just how they’re structured, right? They’re chains of glucose. So bread, rice, potatoes, they’re glucose. So, when you eat them, your blood glucose goes up. If you eat an egg, which is protein and fat, they’re amino acids and triglycerides, they’re not glucose, so your blood glucose doesn’t go up. Doesn’t mean that they don’t have calories. It doesn’t mean that you can’t get fat eating fats and proteins, but it does mean that of the three, the carbohydrates are going to have the biggest effect on glucose, because they are glucose. So, again, not terribly hard to understand.

[00:04:21] So we see that those two interventions have the potential to really transform type 2 diabetes, which is the most important metabolic disease. But if you go out and talk to regular people, like, what’s the American Diabetes Association saying? What’s the dietitian saying? What’s out there? You see that these sorts of interventions are not really embraced at all. We were making pretty good progress up until Covid. Then, of course, Covid hit and nobody really cared about it. So, then it died and now you see a lot of push back. People say, “Oh, it’s all about calories.” It’s like, “Haven’t you talked about calories for the last 50 years?” And there’s a difference between calories from amino acids and calories from glucose, because one is glucose and one is amino acids. [laughs] They both have calories, but they’re different.

[00:05:12] So I thought we’re making actually pretty good progress up until about Covid. Then Covid hit, everything went down because nobody cared about it and it was all about Covid and then now it’s like starting from square one, so a lot of the so-called people who are talking about low carb and intermittent fasting, that’s all gone now. You see, it’s back to the academic centers which are all about calories, and they’re of course getting lots of funding from these food companies and so on.

[00:05:46] We know that the Dietitian Associations, the Diabetes Associations get lots and lots of money from food companies that want to promote this idea that you can have anything you want as long as you eat it in moderation, which is great for their numbers. So, I think it’s tough because I actually am a little bit pessimistic that we will start to make a dent. I was quite optimistic up until a few years ago, now it seems like we have to start that conversation all over again, so it put us back five or ten years almost, the whole Covid thing and it’s a bit unfortunate, so I expect that the diabetes situation will just continue to get worse unless people start listening to people like you, right?

Cynthia Thurlow: [00:06:30] Well and I think it’s helpful for listeners to understand the degree of this problem. It is a systemic problem. It is a problem with messaging, it is a problem with our associations really not focusing in on the bigger picture. It’s not that more medication is going to fix this, it’s that we actually do need to embrace these lifestyle changes. And I would imagine, because when I was still working in the hospital, I would hear this, my cardiac patients that would sit down with these very hyper-processed meals that were supposedly low in salt and low in saturated fat, but very dense, carbohydrate dense. And I would hear the registered dietitians that were in the hospital saying, “Oh, don’t worry, we’ll just cover it with more insulin.” And so, I think that’s been the prevailing wisdom, if you will, that we’ll just give you more medication to fix a lifestyle problem. And what really needs to happen is that clinicians need to be more attuned to the fact that a lot of the nutritional advice and the dogma that we’ve embraced as a culture as clinicians has largely made this situation worse. More medication is not going to fix this lifestyle problem.

[00:07:38] And so, not, ironically enough, I put down some of your biggest pet peeves and I knew calories in, calories out would definitely be in there, and that’s certainly one of mine as well. Talk to listeners about the net impact of hormones on weight gain, because I think that calories matter in the sense that if you overeat any one thing that can become problematic, but understand that overeating carbohydrates in and of itself can set up this cascade of hormonal dysregulation that will likely make things much worse.

Dr. Jason Fung: [00:08:12] Yeah. I think that people who talk about calories all the time are thinking very shallowly. To me, it’s not about the calories, it’s about what’s controlling the calories. It’s not that you’re taking more calories in than calories out, yes, that is always true. But what is driving you to take more calories in versus calories out. And the calories people always say, “Well, it’s your choice,” right? it’s like, “No, it’s not,” because if you’re hungry, you’re going to eat more, that’s just life, and you can’t choose to be less hungry, so it’s not a choice at all.

[00:08:49] So, if the hormones are driving hunger, fear. There are certain foods for example which have certain effects that stimulate certain hormones that make you full. So, you eat proteins, it stimulates peptide YY, for example, that’s a satiety hormone, tells you to stop eating after a while. You eat fat, which stimulates cholecystokinin, which is another satiety hormone that tells you to stop after a while. You eat bulky carbohydrates like salads and stuff to activate stretch receptors in the stomach, which again, signals you to stop eating. So there are lots of hormonal systems which tell you how much to eat, when to eat, when not to eat, it makes you hungry or not hungry, so there are a lot of hormonal systems, and that’s really what drives the calories. So, it’s not that calories are irrelevant, it’s that you’re not looking at the right thing. It’s like first level thinking, not second order thinking, which is important because that’s the root cause.

[00:09:49] It’s like if you were to ask the question, “Why did the Titanic sink?” Then you might say, “Well, it hit an iceberg,” and that’s really the wrong answer. Everybody says, “What are you talking about? Of course, that’s the right answer.” It’s like, “No,” if you think that’s the right answer, then all you say is that to prevent any future problems, don’t hit icebergs, which is stupid advice. It’s like every captain, you must know, “Please don’t hit an iceberg, that wasn’t the problem.” The problem and the root cause is that it was going too fast in an area where it’s dangerous. Same If you have a car on an icy road, you might say, “Why did you crash?” And it’s like, “Well, because I hit a wall.” But that’s not the reason, the reason is that you’re driving too fast for the condition, same with the Titanic, so you’re not looking for that sort of first order thinking, you’re looking for that second order thinking. Same thing with planes, “Why did the plane crash?” Well, “The force of gravity was more than the force of lift.” Of course, it’s true, but it’s not useful. Same as the calories, what you’re looking for is the door blew off the plane and that’s why people got sucked out and the plane crashed. It didn’t crash in this case. But the whole point is that you’re trying to look at what is controlling the calories in, calories out, why are you taking more calories in? Not that you are taking more calories in.

[00:11:11] So, if you say to the Titanic, “Okay, go slower,” then you’re going to prevent another accident. Because you’re getting to the root cause, if you tell somebody, “Don’t hit icebergs,” but they drive really fast, they may still hit an iceberg, and you said, “Well, I told you not to hit an iceberg.” But that’s the same thing as saying to somebody, “Don’t eat so much.” It’s like, why are you hungry? What hormones are controlling it? And we know that it’s all about hormones, because if you look at the drugs that make you gain and lose weight, they don’t control calories, they control your hormones.

[00:11:42] So, you look at insulin, you give insulin, somebody gains weight. Everybody gains weight when you take insulin. Why? Because the hormone insulin is telling you to store more calories, that’s its job, so you’re going to be hungrier and go out and store more calories. Same thing with Ozempic, the weight loss drug. Ozempic does not control your calories, it controls your hunger, by reducing your appetite, reducing your hunger, you’re going to eat fewer calories, and that’s what’s controlling it. But you notice that you’re getting at that sort of deeper level, you’re not trying to control calories, you’re trying to control the hunger, which is controlling the calories, and that’s why calorie counting is so spectacularly unsuccessful. It’s the equivalent of just telling people, drink less alcohol. It’s shallow thinking, right? Because if you’re an alcoholic, it’s all about alcohol in versus alcohol out. That’s true, 100% true. But it doesn’t mean that it’s useful to say, just drink less alcohol or you tell an addict, just take less cocaine, they can’t, that’s the whole point.

[00:12:47] So, if your problem is that you’re eating foods that are stimulating insulin, you’re eating a lot of carbohydrate-heavy foods, highly processed foods, your insulin is high, insulin is going to make you want to eat more, so it’s going to increase your hunger, it’s going to increase your calories, and therefore you’re going to gain weight. So, it wasn’t the calories that was a problem, it was the insulin that was a problem. Same thing with anything, you have food addiction, which is causing you to eat more calories. You can’t just say eat less calories, just like you can’t say take less cocaine. You got to control the food addiction, which is controlling the number of calories or emotional eating. People eat for different reasons. And if people are emotional eaters, you can’t just say, “just eat fewer calories.” It’s stupid, like, it’s incredibly stupid, because if your problem is that you are an emotional eater, then deal with the emotions, figure it out, get counseling, get antidepressants, whatever it is that might or might not help you, and that is going to control the eating– the calories are going to control the weight. But people say, “Oh, of course it’s about calories, it’s all about calories.” You dealt with the eating and yes. But you’re actually trying to understand the problem now. And that’s why it’s such a pet peeve, because it’s so obvious. You got to get to that sort of why are people taking more calories in. For alcoholics, why are they drinking more alcohol? Well, maybe they’re depressed. Then you get counseling, cure– Alcoholics Anonymous is going to help with the reason you’re drinking alcohol, and therefore you’re going to drink less alcohol. Nobody says, “Well, Alcoholics Anonymous is useless, it’s all about alcohol in, alcohol out.”

[00:14:31] But yet for obesity, they say that, they say, “Oh, of course, all calories are the same, all about calories,” But 100 calories of soda is completely different than 100 calories of eggs. Different in terms of insulin, different in terms of satiety, satiation, different in terms of everything. The minute you put those two foods in your mouth, the hormonal response is completely and utterly different. And therefore, why would you expect that they’re going to have equal effects? It’s madness. Like it has no basis in physiology whatsoever. It’s completely nuts to talk about calories as the ultimate arbiter because that’s just the first order thinking. It’s not the second order thinking that you really have to get to the root cause, what’s causing the calories to go up. And it’s the same in almost every problem you can think of. There’s always an easy sort of obvious solution that somebody gets really stuck on, but it’s not helpful.

[00:15:28] If you have a room that’s too full, you have a bar that’s overfilled, why? Well, more people are going in than coming out, obviously. It’s like, “Well, that’s not useful.” So, you don’t say, “Just let people in and more people out.” It’s like the problem is that it was Super Bowl Sunday and everybody was at the bar, so you just have to wait, but if you understand the problem, then you can deal with it, you can’t just say, “Build a bigger door,” but that’s the calories thing, it’s all about the hormones, because our whole body, everything in our body is controlled by hormones and therefore, you have to look at the hormones, you have to look at the deeper reasons why people are not getting what they want.

Cynthia Thurlow: [00:16:05] Well, and I think given the fact that our metabolic health in most westernized countries is heading in the wrong direction, largely. I think this reductionistic thinking about just solely focusing on calories and controlling variables is missing the big picture, as you’ve so beautifully identified. And I just interviewed Dr. Jud Brewer last week and we’re talking about true intrinsic hunger versus hedonistic hunger. And you’re really speaking to that as well that helping your patients understand that if you eat a large meal and you’re continuing to want to eat it is probably for reasons beyond the obvious. It very likely could be, you know, you could have some leptin resistance or could be some insulin resistance that’s driving these choices, or if you sit down and have a big bowl of pasta versus having a large piece of protein and maybe some broccoli, you’re going to get, in many instances, a very different response post meal. You were mentioning these key hormones, stretch receptors, peptide YY, cholecystokinin, if you eat enough fat, that’ll tell your brain that you’re full. But for a lot of individuals, many individuals, they don’t get those cues and they are shamed into believing it’s a lack of control where they just need to control their calories and that’s going to lead to weight loss and it’s far more complicated than that.

Dr. Jason Fung: [00:17:23] Yeah. And what happens is that then some ultra-processed food company says, “Well, you should eat this highly, highly processed bar instead of a good nutritious meal because it’s only x amount of calories,” Then they grab, they go fun– they sell product by getting all these academic doctors to say “That’s all about calories and nothing else matters, and eating real food doesn’t matter, so just eat this highly processed slop and it’s fine,” And people believe them because they’re like, “Oh, they’re from this university or that university,” But it’s not true, the whole idea in calories is not wrong, it’s just very simplistic to the point of uselessness.

[00:18:10] Same as alcohol in, alcohol out. It’s not a useful concept for anything or people in versus people out of a room, it’s not useful. You have to get to that second order thinking, which is where you’ll actually make a difference, which is why no intervention that targets just calories has succeeded. I’m not sure how many more decades of research we have to do before people are finally convinced, like they’ve done hundreds of studies on calories reduction and millions and there’re probably billions of people who really have done calorie-restricted diets, it pretty well just doesn’t work in anybody. There are people, of course, who succeed, but mostly when people try to lose weight, they also try to improve the quality of their food, so a lot of times the calorie thing gets lost, because you try and give up the pizza and French fries and eat salad. So even though you think you’re just changing your calories, you’re actually changing the entire composition of your meal and your hormonal balance. So, people say, “Well, it’s true,” it’s not.

[00:19:13] And there’s another aspect, which is you’re talking about the hedonistic. I’m always reminded that it’s so silly because it’s obvious, but it never seems to be obvious to academic physicians, because some people talk about the Kempner rice diet, which is this diet in the 30s where people ate rice and sugar, that’s all they ate, just rice, white rice, sugar, so pure, refined carbohydrates, and people are like, “Oh, yeah, you could lose weight on that.” Well, of course you can lose weight on that. If every single day you ate white rice and sugar, you’d be tired of it in about four days, then you spend another eight months eating rice and sugar. Well, what’s going to happen is pretty soon, as soon as you have no hunger, you are going to stop eating that rice and sugar because it’s so boring. You eat for two reasons, one is hunger and sustenance, and one is for pleasure, and we do both. So, if you have no impetus to eat for pleasure, because white rice and sugar just doesn’t taste that good after eating every single meal of rice and sugar, you’re just going to stop eating as soon as the hunger is gone. And you’re not going to eat until you’re really hungry because all that you can eat is rice and sugar. So, of course it’s going to work because you’re controlling what you’re eating in that manner by really reducing the pleasure of eating, so it’s going to work, it’s just nobody’s going to stick to it. And people talk about this as if the proof that the carbohydrate model doesn’t work, but it’s really just that they don’t understand.

[00:20:49] And again, it’s so obvious. If the Kempner rice diet was so good, why has nobody used it for like a century? It’s not like the ketogenic diet where it fell out of favor, but now it’s sort of people are using again and finding, “Hey, it is useful,” over the low-carbohydrate diet, which has been around since the 1800s and1850s. So, it’s like, everybody talks about it like it’s some giant fad, but it’s been around for close to 180 years, so it’s not that big of a fad or intermittent fasting, which has been around for 2000 plus years. These things have been around a while because people use them and find them successful. The Kempner rice diet died and nobody’s trying to revive it, so it’s not proof of anything. To use that as an argument and I see it sometimes people say, “Oh, what about this?” It’s like, if you think it’s so great for you, go ahead and [Cynthia laughs] use it, you do it, you follow it. Like, I’m not following that diet. It’s just not feasible.

Cynthia Thurlow: [00:21:45] And definitely not sustainable. I can’t imagine anyone listening would think, “Hey, I really want to stick with a predominantly rice and sugar diet, that’s going to be really enjoyable.” I think we would get tired of it pretty quickly. Now, I’d love to pivot a little bit and talk about the impact of metabolic health for middle age women. A lot of questions Dr. Fung came in around here. Women, in many instances, maybe in their 20s and 30s, they don’t deal with a lot of weight loss resistance, but certainly, as women are navigating 40 years of age and older, the hormonal changes that are happening, early perimenopause and menopause. What has been your experience as a clinician, obviously working with thousands and thousands of female patients, what are some of the unique challenges that you see as a clinician in dealing with women as they’re navigating these hormonal fluctuations with sex hormones and insulin sensitivity in middle age?

Dr. Jason Fung: [00:22:40] Yeah, it’s a difficult one and it sort of goes again to the whole hormonal basis of a lot of what we’re dealing with. So, if you think about– And I think this to me is one of the, like, in terms of calories in and calories out, people talk about definitely calories in and calories out, it’s definitely not. Because if you take sort of puberty, what you see is that before puberty boys and girls are roughly the same weight, roughly the same body fat percentage. Then you hit puberty and boys gain a lot of muscle and girls gain more fat, that’s just how it happens. About 50% more fat on average. So, if weight gain, fat gain is all about calories in, calories out, like in willpower, then what do women– just have no willpower? Or what is the problem here? And the problem is obviously hormonal, not the problem. But the difference is that boys have a lot of testosterone, so they tend to gain muscle and women have different sex hormones, estrogen, progesterone, and so they develop different levels of body fat. So, you see that it’s definitely 100% hormonally controlled. It’s not what they ate or decided to eat or whatever.

[00:23:46] Same thing happens on the other side. So as men get older, they actually start to get less testosterone too. And when you get less testosterone, you tend to gain less muscle and gain more fat. And unfortunately, it sort of happens with aging and I’m not a sex hormone expert, but it seems to be happening more also in the general population. So overall, testosterone levels seem to be lower for some reason that I’m not entirely clear on. And in women, it’s a little more obvious because they go through menopause and therefore, they have different hormonal changes, again, dealing with testosterone, estrogen and progesterone. Unfortunately, I don’t know of any intervention that can change that. On the Internet, they have all these things, oh, boost your testosterone here and there. I’m not entirely clear that whether they work or why they would work, but the problem is that it is going to be a headwind for people as they get older, both men and women in that age group, middle age group, because there are changes to sex hormones that do affect body composition. What can you do about it? There’s not that much to change the sex hormone, so if you’re very, very low in testosterone, for example, then you could take testosterone replacement. You can get somebody to check your estrogen, progesterone levels and see if hormone replacement is beneficial for you.

[00:25:09] That’s been a super controversial topic for a lot of years. So over 20 years ago, everybody got put on hormonal replacement therapy. Then there was a big thing about breast cancer, could it be causing a lot of breast cancer? So then everybody moved away from hormonal replacement therapy. There was a scare about testosterone replacement causing heart disease and prostate cancer. Whereas 20, 25 years ago, everybody was talking about hormonal replacement therapy for women, testosterone replacement therapy for men, now they’ve gone to almost zero and I’m not sure where the right answer is, but it probably falls somewhere in the middle there.

[00:25:44] So if that’s the root problem, of course that’s hard to fix, so you can’t really fix that. So, then you get back to trying to adjust your diet. So again, trying to do those things and adding the intermittent fasting, which not only is a way to control your hormones, but also a way to impose a structure on your eating day. So, if you have a rule, for example, that you don’t eat after 07:00 PM, then it makes it easier to follow, because you know that’s a rule, that’s just a way, after a while, it just becomes a way of life, it’s about building that healthy habit that’s going to keep you there. And it’s very important to build habits because habits don’t take willpower and it establishes a baseline for you.

[00:26:26] So, this is why it’s so important as opposed to say counting calories where you go, it can work, but you’re not developing any easy-to-follow habit because every day you’re eating different foods, so you’re not developing any good habits that are going to keep you there. Every day you’re just trying to count, count, count. As opposed to fasting, where you might say, “Okay, well, I won’t eat before this time, I won’t eat after that time.” After a while, you’re not going to get hungry at that time. I know because I’ve done it for a while. And people say “It’s hard at first and then after two weeks is just the way it was.”

[00:26:43] So, from a behavioral standpoint, there are a lot of benefits to that as opposed to the other. And those are the things that have to focus on in terms of trying to combat that, because the root cause of the problem around menopause, which is the sex hormone changes and also the testosterone in men, you can’t actually fix that very easily without testing, without drugs and so on, so that’s why people have trouble, and it’s not their fault, it’s just something else that you have to consider, so you try to do what you can with what you have control over, which is your diet, the foods that you eat and the times that you don’t.

Cynthia Thurlow: [00:27:34] Yeah, you bring up so many good points. And for everyone that’s listening, Dr. Fung is alluding to the Women’s Health Initiative that was published in 2002. And this is when a whole generation of clinicians became very fearful about prescribing hormones. Patients became fearful about taking hormones. I think things are swinging the opposite direction as we’ve started to look a little more closely at that study that was done. And it’s interesting to me that menopause, if women live long enough will happen and absolutely that will occur. And same thing with men, men will go through andropause, which is probably not nearly as spectacular in terms of hormonal situations. But you will see middle age men in many instances that are dealing with body composition changes and they may start becoming more insulin resistant. And do you find that your middle-aged women, when they’re weight loss resistant, do they seem to do better with longer prolonged fast? Because I’m always trying to find balance with maintaining muscle, which sarcopenia is a real issue, and so trying to find that balance. And I think the longer I’ve been intermittent fasting, the more I’ve started to get very granular about this topic in particular, because I know fasting in general can beneficial with growth hormone and therapeutic utilization of fasting. But with those longer fasts, some of the longevity experts talk about these three, five, seven-day fasts, what are your opinions about this specifically to women in this middle age group who are dealing with weight loss resistance?

Dr. Jason Fung: [00:29:02] I think it can be very useful, but you have to use it in the right situations and that’s always the case. Because there’s always these people, it’s always like, “Oh,” so they’ll go crazy on something like fasting, so they’ll do like a fellow for instance, he’s not overweight, but he’ll do a five-day fast, like every month and they’ll be like, “Oh, it’s like the worst thing.” It’s like, that’s because you’re not really the right person that’s supposed to be doing this, you don’t have weight to lose. And then they come out, and then they’re like, “Oh, fasting is so bad for you.” I’m like, “No,” fasting is just a tool. If you’re lean and muscular and don’t have a lot of fat, why are you doing five-days of fasting every month? That’s a lot. It’s more than what people normally do.

[00:29:47] So, it’s all about the situation. So, the thing about muscle is that there’re a lot of people who talk about muscle loss in conjunction with weight loss and it definitely happens, for sure, it happens, but the fasting is not particularly better or worse, okay. So, if you have a prolonged fast, I mean, it’s been fairly well studied of what happens, you do have a small amount of protein loss at first and [unintelligible 00:30:21] gluconeogenesis, but protein is not muscle. What you’re doing is you’re breaking down protein, which includes the connective tissue and skin and all this other stuff that should be broken down, and it’s very good for you. As you go into sort of two, three, four days, most of your energy is coming from fat, and you go into this sort of protein conservation mode, so therefore, you’re not burning a lot of protein.

[00:30:43] What’s interesting is that when you actually measure this, what you find, and there was one study that actually looked at how much water you lose. So, they did put people on like a five-day fast and so on, and they measured the water weight that was lost. And when you measure it with certain types of measurement, it looks like, is that you’ve lost a lot of muscle in a five day, seven day, one of these longer fasts. But when you actually look at it very, very carefully, it’s actually mostly water.

[00:31:15] So, glycogen, for instance, if your muscles use glycogen, you’re going to lose it. Glycogen carries a lot of water, so then your muscles are smaller, they’ve lost that glycogen, they’ve lost that water. It looks like you’ve lost a lot of lean mass, it looks like you’ve lost a lot of muscle, but actually you’ve just lost a lot of water. And most, I think, 80% of the weight loss there was actually just water weight. But it looks like that when you use these other measurements, especially the sort of DEXA scans and so on. The DEXA scans are incredibly inaccurate during long fasts. So, what you see actually all the time is that–

[00:31:48] So, for example, one patient who’s very, very into this sort of measurement, he did a long fast and then he took his DEXA scan, and then he said, “Wow, on a five-day fast I lost like 10 pounds of muscle in my trunk.” And I’m like, “Okay, that’s bizarre, why would you lose 10 pounds of muscle in your trunk?” And then, of course, he started to eat again. And then after another week or so of just regular eating, he regained all that muscle. It’s like, so, do you think it’s a measurement problem or do you think you actually burned off 10 pounds of muscle, and then without particularly exercising, you just regained 10 pounds of muscle [Cynthia laughs] for no reason or do you think it’s just a measurement issue, right? Of course, it’s a measurement issue. You just don’t lose muscle that fast.

[00:32:31] And people always confuse two issues, because if you think about muscle, you gain muscle because you use it and you lose muscle because you don’t use it. It doesn’t have heck of a lot to do with what you eat and you don’t eat. It’s really about using it. That’s why when people go up into space or when they’re bedbound, they lose muscle extremely quickly because you’ve taken the entire load off, so you’re going to lose muscle. It’s just the way that it is, but it doesn’t mean that your diet has anything to do with it particularly. As people lose weight, their muscle mass also tends to go down and people worry about that, but think about it, say you lose 50 pounds, what’s happening is that you are putting 50 pounds less weight on your frame, on your muscles, so if you’re pushing around 50 pounds, going up the stairs, down the stairs, you’re walking around you’ve got 50 pounds of more muscle, like if you put a 50-pound backpack on, a big sack with weight, and you did that every day, you’d gain muscle.

[00:33:33] Now you take it off, you’re going to lose muscle. That’s just going to happen because you’re actually using less muscle. Because if you’re 50, 80, or 100 pounds more, you need to carry that around every day. Every single step that you take has an extra 50 pounds. You’re going to build more muscle. So now you lose that weight, you’re going to lose muscle. So, you have to expect that there is going to be some muscle loss, but it’s not because of your diet, it’s because you’re not using it as much. So, muscles grow when you use them, muscles don’t grow when you don’t use them. And then people talk about, “Oh, you got to eat more protein, the fasting does this.” They’re separate issues, right? Why are you confusing the two issues? Yes. In the extreme, if you eat like zero protein, yes you probably will lose muscle because you don’t have the amino acids to build muscle. But where people sit mostly in sort of a regular 0.8 to 1.2 g per day thing and it’s like, well the protein is probably adequate for what you need, you need to put more weight on to build it.

[00:34:37] Sarcopenia, as you get older, a lot of it is related to people are being less active as well. And lower testosterone, we know that also leads to less muscle growth. So, there’s a variety of issues that go on with muscles and muscle loss. But diet is sort of a relatively peripheral thing unless you’re doing extreme diets. On a long fast, again, you’re not losing as much protein as you might think, but if you’re losing weight on the long term, you will lose some muscle mass due to decreased usage of muscle. So, I wouldn’t worry about it particularly. You have to see why? Like if you’re overweight and have type 2 diabetes, then the fasting may benefit you in huge ways. But yes, you will lose some muscle. With any type of weight loss, you see that. With long term, like long fasting, I don’t think it’s particularly worse than any others, but if you measure yourself all the time.

[00:35:36] And in this study where they looked at the DEXA scan, they actually did a very interesting thing, which is not only did they measure it with the DEXA scan and found that mostly water weight, they actually tested the strength by having people do maximum lifts. And people are actually stronger after a seven-day fast. Why? Because maybe their sympathetic tone was up, maybe something else, but clearly, they weren’t weaker. When you measure the mass of the muscle, you say, “Oh, you’re losing muscle,” but when you actually test it, I think either their truncal strength was higher or their axial strength was higher, I can’t remember which one, but they were actually measurably stronger than they were before they did the fasting. So again, tell me what’s wrong with that.

Cynthia Thurlow: [00:36:16] No, it’s so helpful. What’s interesting to me is bio individuality definitely plays a role in the success of whether or not someone is intermittent fasting, whether it’s a daily intermittent fast or it’s something that maybe they’re doing three, five, seven-day fasts. Thank you for all that good information and the limitations to a DEXA scan, because although this is an inexpensive test, it is not an imperfect test and only gives us a bit of information, but not the full picture.

[00:36:45] Now, when we talk about weight loss strategies, obviously we’ve talked about intermittent fasting. We’ve talked about low-carb or carb-restricted diets. What about the unique circumstances of individuals that are dealing with shift work, whether they’re physicians or nurses or techs or whomever, people that work in the hospital, we know the disruption of our circadian rhythms can play a huge role in challenges related to weight gain and cravings and all sorts of different factors that can influence weight.

Dr. Jason Fung: [00:37:15] Yeah, that’s a real tough one and again, we know stress plays a huge role in weight gain, weight loss. Again, people always confuse a lot of things, but what we’re looking for are causes, right? We’re not looking for correlation, we’re looking for causes of what we used to do, right? So, if you give somebody insulin, they gain weight, you take away insulin, they lose weight, that’s a causal relationship. You can do the same thing with the stress hormone cortisol, because you can give somebody prednisone, which is a synthetic form of cortisol. You give people prednisone, people gain weight, that’s just what happens. So, therefore, you know that excess cortisol is going to lead to weight gain.

[00:37:48] So the problem with shift work is that it’s hugely stressful, because the way we’re designed to work, which is sleep at night and get up during the day, is flipped around. And so therefore, there’re all these secondary effects of that shift work. Again, the problem is that if that’s the cause of your issue, your weight gain, then until you fix the cause. You’re looking for root causes, right? And this is where people always get confused because they’re always like, “Well, just eat less calories,” but the calories wasn’t the problem, the problem was the shift work, right? It’s the same with the fasting, like you can’t use fasting to fix it because it’s the shift work that was the problem, so it’s not a panacea everybody tries to fix it, but the best you can do is try to normalize your cortisol levels as much as you can. Try and reestablish some circadian rhythm when you can. Because again, hormones go up and down and there’s a natural rhythm, so in the morning you have certain hormones that go up and then they go down, but now you’ve screwed that whole thing up with the shift work, so it’s a tough branch of that because it’s like once you identify the cause, then you have to see what you can do about it. But if your work requires that, sorry, there’s not so much that you can do about it. You can try and adjust other things, you can adjust your diet, you can try and eat at certain times, other times to try and mimic it as closely as you can, but until you get rid of the actual stress, which is the shift being up all night, then it’s hard to completely fix that.

Cynthia Thurlow: [00:39:27] Yeah, it’s interesting. I did nights when I was first a nurse in the ER in Baltimore. And I remember within two years of doing that, I remember begging because the newer nurses got stuck on night shift. And for some people they did really well with it, but for me, I walked around nauseous all night long, I could never get back on a normal sleeping pattern on days I wasn’t working. And there were many people that I worked with, they did that for 20, 30 years and they always looked significantly more tired, haggard, and they would talk about the fact that, you know for circumstantial reasons they had to work nights because they had young kids or financially, they needed the differences in pay. And certainly, when physicians are training, they have all sorts of wild schedules to provide hospital coverage.

[00:40:11] So, if you’re hearing this and you’re a shift worker, if you have the ability to shift to a different, even if it’s 11 A to a 11 P, you know, doing an evening might be a whole lot easier on your circadian biology. What are your thoughts surrounding– and we touched on this, but lots of questions came in surrounding the GLP-1s. Now we have this class of drugs, we’re seeing not even just obese or overweight or metabolically unhealthy patients that are using these drugs. I have colleagues in the health and wellness space that are using them to take the edge off of their appetites. What are your thoughts on GLP-1s? Do you feel like they’re a good adjunct to metabolic health? Do you think they can be abused? What are your thoughts?

Dr. Jason Fung: [00:40:50] Overall, I think they have their use. I wrote a blog on medium.com but I wrote about it and the way they work is that they basically reduce your appetite. They do it in various ways, so it slows down gastric emptying so that your stomach normally holds food and then slowly releases food. When your stomach is full of a lot of stuff, you signal the brain through the sympathetic nerve and the vagus nerve, and it tells you, your stomach is full, don’t eat anymore, so it’s a very powerful signal. So, if you slow down gastric emptying, then the stomach stays bigger for longer and therefore you don’t want to eat.

[00:41:35] It also has direct effect in the brain itself. So, it acts at this thing called the subfornical organ and the area of postrema, both of which have lot of GLP-1 receptors, and the blood brain barrier is very weak at those points, so it causes not just a suppression of appetite, but in the area of postrema, actually causes a lot of nausea. That’s why you have like 89% nausea, vomiting as a side effect with these drugs. It’s just how they work.

[00:41:58] So if your stomach is full, then you don’t want to eat. If you’re nauseous, you don’t want to eat. And if you’re activating these other receptors, then you don’t want to eat. So, it basically turns off appetite. So, it can be useful for certain people. So, type 2 diabetes, if you turn off the appetite, then you don’t get hungry. Don’t want to eat because you’re nauseous and therefore you eat less, and your body’s going to burn the sugar, which is very good, and that’s probably the major effect. And that’s why these drugs, it’s not like GLP-1s are new. The GLP-1s were actually developed and FDA approved in 2005. It was just that they developed longer and longer release forms that had more of these side effects, which are actually the main effect. That’s the sort of effect of the GLP-1s is the appetite suppression and therefore it can be very useful. So, I have nothing against these. They certainly have a role to play. The problem is that if you simply use these drugs and don’t learn how to eat, then you’re no really better off than–

[00:43:05] You know, for years we thought that bariatric surgery would cure obesity, of course it didn’t, it did for a while, but if you eat around the limitations of the surgery, then you’ll gain your weight back, so it’s the same thing. So, what we see is that you have to stay on it in order for it to have its effect. And people say, “Well, what’s wrong with that?” Because you stay on blood pressure pills for years and years. And the difference is that you’re losing one of the great pleasures of life. We talk about eating, you eat for nutrition and you eat for pleasure, that’s just the way life is.

[00:43:40] Now, suppose you take this GLP-1 and you no longer have any pleasure in eating, think about it, think about a time that you ate a huge, you know, all you can eat buffet. Now somebody plops a juicy steak in front of you and you’re like, [mimics retching] because you’re full. It’s a great steak, if you’re hungry, you’d have loved it, and maybe you ate a lot of it just half an hour ago, but you’re full. So now imagine you’re like that all the time, you can’t enjoy your food anymore. Why? Because you’ve turned off that whole enjoyment of food. Your body thinks you’re full. You can’t enjoy your food anymore.

[00:44:19] So what happens is and I’ve been using them quite heavily, the Ozempic drugs, because they actually have benefits in terms of– When people lose weight, there’s a lot of medical benefits to that. But a lot of people think that they’re going to change everything, people don’t stay on them. And so, for six months, it’s great, you’ve lost a lot of weight. Everybody’s like, “Oh, you look so good.” You’re healthier because you needed to lose the weight and you did, you are healthier, but the problem is that you can’t enjoy food and that’s sort of one of life’s great pleasures. So, now it’s okay for three months, it’s okay for six months, now it gets to a year, now your weight loss starts to plateau, nobody’s commenting on your looks anymore because you look the same as you did before. You haven’t lost any more weight because eventually it plateaus, but you still can’t enjoy your food. Now you’re starting to think I’m a little nauseous all the time. Nobody’s commenting on how great I look anymore and I’m not losing any more weight, but I’m still not enjoying myself. Life is a little less enjoyable because I can’t eat and is it really worth it?

[00:45:23] So, in the New York Times, they had this article about people, and they said after a year, only about a third of people stay on this drug, especially at the high doses. And I’ll tell you, I’ve been using them pretty heavily since about 2019 because in Canada and Ontario, it was covered for type 2 diabetes in 2019, so the government would pay for it, so, I prescribed it because it was useful for type 2 diabetics in conjunction with their diet. But the difference is, of course, we are using lower doses, but a lot of them came off of it. A lot of them just wouldn’t take it anymore. A lot of them take a lot lower doses than I prescribed because they just couldn’t tolerate it anymore.

[00:45:59] So, it’s like the difference between a blood pressure pill and taking Ozempic for years and years and years is that blood pressure pill doesn’t take away one of the great pleasures of life, the Ozempic does, so is it useful? Sure, it’s useful, but I think in the end, it’s still going to come down to some combination of, yeah, there are drugs that can help you, and I’m not against drugs. I prescribe drugs all the time, but in the end, you’re still going to want to know how to eat properly, develop good eating habits, understand what foods are good for you, not good for you, so that you can enjoy yourself. Because with fasting, sure, you don’t enjoy yourself eating while fasting because you’re not eating, but when you do eat, you do enjoy yourself. So, you’re getting enjoyment as you go, as opposed to Ozempic, which is you just lost your enjoyment for food forever, every day, that’s hard to take, it’s not easy. People think it’s great, but it’s not.

Cynthia Thurlow: [00:46:57] Yeah, thank you so much for that, because it was a side of things I hadn’t really considered, but it makes a great deal of sense, and it can also explain why maybe people will stay on a GLP-1 for three, six, twelve months and then they want to go back to being able to enjoy eating, even if it’s healthy food. Now, are there any other supplements or other strategies that you’re using with your patients right now or do you use berberine? I got a lot of questions about supplements. I thought to myself, I’m probably going to guess no, but I wanted to ask.

Dr. Jason Fung: [00:47:31] Yeah, most supplements– I mean, we don’t prescribe a lot of supplements. So berberine, I don’t use much, it’s not that popular up here in Canada, so I don’t have that much experience, I don’t have a lot of people on it, and the data is sort of equivocal on whether it’s beneficial or not. If it helps you, then I have nothing against it.

[00:47:48] In terms of supplements, there’re only a few supplements that we use a lot. Magnesium is one of them. And I did a video about the magnesium. So, magnesium is very interesting because a lot of people, especially these days, may, in fact, be very magnesium deficient because the soil that we grow our foods in has become very depleted in magnesium because we grow the food, the food has the magnesium, but then when we put fertilizer back in, it has nitrogen, phosphorus, potassium, but not a lot of magnesium. So, people used to do things in the old days, there’s something called bone meal for example, where you’d have bone, you’d crush it all up and throw it in. Bone has a lot of calcium, has a lot of magnesium. But so, then you would replenish the soil. And I remember I was reading about this where people would take bone like 90% or 95% less magnesium in the foods that we eat compared to 50, 60 years ago. But then you think that okay, you say you eat a lot of meat, for example. Well, if the cows are eating the grass that has no magnesium, then the cows also don’t have magnesium.

[00:48:47] And a friend of mine, Dr. David Unwin, who raises livestock and stuff, he says he always has to give magnesium to his animals because they’re actually quite deficient in magnesium. So even if eat or not, into plants, and you want to eat meat, well, you’re still going to get magnesium deficient because you’re not getting it. We used to get it from seafood which again came from the sea, but a lot of seafood now is farmed as opposed to wild, so again, it’s not quite the same. So, magnesium is a very important supplement that might be– It’s relatively easy and I did talk about in the video about the different types of magnesium supplements, that’s one.

[00:49:20] The other one is electrolytes. We get asked some question on electrolytes sometimes, and they’re useful. So, there’re three electrolytes that a lot of these– So, there’s another company, Enzymedica, who does fasting supplement. It has a bunch of electrolytes and the main ones you worry about is salt, potassium, and magnesium. So, magnesium we talked about. But salt and potassium are sort of, again, if you’re fasting, it’s very hard to get the salt that you need especially if you’re active and sweating, because sweat is going to have salt and potassium, so you’re losing it, but you’re not taking it in, because if you’re just drinking water, you’re not getting a lot of salt and not getting a lot of potassium, so that’s why sometimes we have people do bone broth, which is not a true fast, and then there you can put salt in, because if you’re drinking coffee, it’s hard to put salt in it, whereas bone broth, you can put salt in it, so you’re getting that salt, you’re getting some electrolytes in it. If you don’t want to do that, some people use supplements from that standpoint.

[00:50:19] Sometimes these things have other things like amino acids and some put stevia in it, which I’m not crazy about, but it makes it taste better so. Again, we’re not trying to be like perfect right. If you take a supplement and it really helps you go longer, then you still have a net benefit, even if it does have some stuff that I’m not fully supportive of, but so those are the two main ones, magnesium and then electrolytes, particularly salt. And we’ve had people who even just take salt straight, like during fasting, and they find it very helpful for them. People who get sort of lightheaded during fasting and stuff, they’ll take salt. So salt, potassium, magnesium are the main supplements that we talk about. There’re lots of supplements out there and I think they can have a specific benefit, but you have to really be– You’re taking things like turmeric and stuff, there’re all these different things that might beneficial, but specifically for us, that’s the ones that we look at.

Cynthia Thurlow: [00:51:13] No, that’s so helpful. And to me, it’s always very validating when you talk so much and place a great deal of emphasis on electrolytes because I’m a huge proponent of them as well. We’ll make sure we link up your Medium article on the GLP-1s as well as your YouTube video on magnesium. Please let my listeners know how to connect with you on social media, how to purchase your books, which are a wonderful compilation I recommend them all the time.

Dr. Jason Fung: [00:51:36] Yeah. So, on social media, you can go on Twitter @drjasonfung. On YouTube, I have a lot of videos on there. And just look under my name Jason Fung and you should find. There’s a whole lot of videos on fasting, on low carb, on diabetes, on various things. And I find it great because it’s free for people, people can watch whenever they want, they can go back and watch and listen, so I found that a very good thing to do. On medium.com is where I kept my blog. You used to be able to get a bunch of free articles every month, but I think they stopped it, which is a bit of a pain. But on the other hand, it’s where I have my blog, so I never bothered to change it. I think it’s $5 a month for Medium. If you subscribe to The Fasting Method newsletter, I think I often include the link that you can get, which is called the friend link, so you don’t have to pay for it because the point was not to make people pay for it, the point was it was just an easy place to keep my blog. And then for the books, you can buy them anywhere, you can also look on my website, doctorjasonfung.com and that just has all my books listed there. Amazon’s probably the easiest place. I link to Amazon just because it’s the easiest place for people to get them. But really, at any bookstore, you could probably ask for them.

Cynthia Thurlow: [00:52:50] Well, thank you again, Dr. Fung. It’s always a pleasure to connect with you.

Dr. Jason Fung: [00:52:53] Great. Thank you so much, Cynthia.

Cynthia Thurlow: [00:53:02] If you love this podcast episode, please leave a rating and review, subscribe and tell a friend.