#262 – How do lifestyle changes affect your metabolic health? | Dr. Robert Lustig & Ben Grynol

Exercising and changing your diet are both beneficial for metabolic health. But you may be wondering which one has more benefits for fat loss, increasing insulin sensitivity, and more. Dr. Robert Lustig and Ben Grynol discuss the answer to this burning question and more, including how exercise, saunas, stress, and sleep affect glucose levels.

2:30 — Why do you get a glucose spike when you exercise?

When you exercise, you may see a glucose spike on your continuous glucose monitor (CGM). That’s expected and nothing to worry about.

When you exercise, you activate the sympathetic nervous system. Now, the sympathetic nervous system is the part of your nervous system that is the fight-or-flight response. In the process, the sympathetic nervous system will activate and will send nervous impulses to the liver. The liver will then release all of the stored-up glucose that it has in the form of glycogen. Glycogen is what you make in response to eating a meal, especially a high-carbohydrate meal, glucose for a rainy day. This is why marathoners carb-load before a race, because they’re trying to build up their liver glycogen stores so that they can release them during the race. So, when you start exercising, your liver will take that glycogen and turn it into glucose and release into the bloodstream. That will lead to a rise in your serum glucose; that will lead to a glucose spike. And then that glucose is available for muscles, for the brain, for the kidneys, to be able to metabolize energy while you are exercising. And it will stay up, either until the liver runs out of glycogen, which takes about three hours, or until you stop exercising. In either case, your glucose will then fall precipitously. So if you stop exercising, you will clear that glucose spike very rapidly.

4:22 — The sport drink industry puts fructose in its products

That fructose will get converted to glucose to keep powering an athlete’s endurance performance. However, most people don’t need fructose for exercise unless the activity goes on for hours.

If you are on the football gridiron exercising like crazy, your glucose will start falling precipitously and you will all of a sudden become very tired because you have run out of readily available glucose. This is one reason why the sports drink companies put fructose into the sports drinks because that’s another way to generate glucose when you’re exercising. And it’s true. If you are a gridiron athlete, an elite athlete, that fructose in that sports drink will ultimately get converted back into glucose and will help replete the glycogen that your liver has lost. No one else needs the fructose for anything else. But the bottom line is you will clear a glucose spike rapidly because you have stopped exercising.

5:27 — What happens to your glucose when you enter a sauna?

Your body will perceive the heat as a stress. This activates your sympathetic nervous system (your fight-or-flight response), which primes the liver to release glycogen, leading to a glucose spike.

The heat is a stress, the stress activates the sympathetic nervous system, the sympathetic nervous system goes to your liver and causes glycogen to be released, and so it will generate a glucose spike all by itself with having eaten nothing. Just from the epinephrine being released, it will cause a glucose rise. That glucose will clear quickly because your insulin will come up to meet it and it will go away. It will have caused no damage and will be gone very quickly. But that’s also one of the reasons why after you’ve been in the sauna you want to go take a nap afterwards, is because you’ve actually totally depleted some of your glucose stores and you need time to replete them. So enjoy your nap.

6:26 — Is it better to exercise or change your diet?

Both are incredible lifestyle changes for boosting your metabolic health, cardiovascular health, and overall health, and for lowering your risk of premature death. However, if you could only choose one or you want to start with just one, changing your diet has more potential.

We’ve gotten sick in the last 50 years because of the changes in our environment. And our environment has changed in multitudinous ways. Our diet’s changed, our sleep cycle’s changed, our capacity and opportunities for exercise have changed. Our stress has changed. Our exposure to toxins has changed. Bottom line: in order to achieve optimal metabolic health, we have to work in every single one of those venues. How do we do that? Well, we can’t. We can’t fix ’em all. But there are certain ones that we can. The one that’s immediately available and the one you can fix today is your diet. And the data show that if you fix your diet, your cardiovascular mortality risk drops by 35% to 40%. Now compare that to if all of a sudden you started exercising—now that’s also good—but the data show that if you start exercising, your improvement in cardiometabolic mortality risk reduces by a total of 25%. Which is better? Thirty-five percent to 40% or 25%. Both good; do both. But if you had to do one thing, make it diet. Number one, you have complete control, and number two, you can make your own food. And number three, it works best.

8:16 — How cortisol, the stress hormone, impacts blood sugar and health

Cortisol is a stress hormone. It is made by the adrenal gland. It circulates in the bloodstream. And what it does is it raises the serum glucose in order to provide more energy for the brain so that the brain can still run even when there’s no glucose available. And it will actually start taking away from muscle. It will actually cause the dissolution of muscle in order to keep the brain fed. Chronic stress is the opposite of acute stress in terms of the physiology and in terms of the glucose requirement. The goal of chronic stress is to feed the brain because the brain is the highest glucose demander. It requires the most glucose all the time because it doesn’t have a place to store glucose. So cortisol lifts energy from the rest of the body and makes sure that the brain gets it. Well, that has negative effects on the brain, and it also has negative effects on that glucose excursion because glucocorticoids actually interfere with mitochondria and interfere with the ability to produce ATP in many of those organs. Cortisol dissociates the energy availability from the energy utilization. It actually inhibits mitochondrial function. And so the higher the cortisol, the bigger the glucose rise, but the less well you’re going to clear it. Because glucose interferes with mitochondria, you see the effect as insulin resistance. In fact, the more stressed you are, the higher your fasting insulin because the less well your mitochondria are working. And the only way to fix that is fix the stress. Now, that’s pretty hard to do.

10:36 — How does sleep affect your metabolic health?

Sleep deprivation is a stressor. And it increases a hormone that is responsible for hunger.

It’s not a shocker that adults and children are getting less sleep than they did before. In fact, 35% of adults get less than seven hours of sleep per night. And 23% of adults are chronic insomniacs. The question is, What does that do to your metabolic health? And the answer: it does two things, both bad. The first is it’s a stress. It raises your cortisol. And we’ve already talked about cortisol being a mitochondrial dissociator; it creates heat instead of creating ATP. That’s bad for your metabolic health because now your cells are basically running on empty. No wonder you feel lousy. Second, sleep deprivation increases a hormone that is responsible for hunger, that is released by the stomach, called ghrelin. Ghrelin is released in response to sleep deprivation, circulates in your bloodstream, goes to your brain and says, “I’m hungry. Feed me.” And so you end up eating more, which will only raise your glucose excursions and your insulin response and generate increased fat and of course chronic metabolic disease. And so chronic sleep deprivation affects cortisol, driving metabolic dysfunction, and ghrelin, driving increased eating. Everyone thinks that “Oh, I’m eating more because I’m up longer.” No, you’re eating more because your ghrelin is dysfunctional.

12:22 — How do you fix sleep deprivation?

Screen time and notification can hinder quality sleep.

How do you fix sleep deprivation? Well, one way is cut the caffeine, because caffeine is exactly what’s wrong with sleep. But that’s not the only thing. The other thing to do is take the screens out of your bedroom. Studies show that children who sleep with their phones charging in their bedroom get 28 minutes less sleep per night than children whose screens are charging outside their bedroom. The blue light by itself alters the diurnal rhythms of the brain, ultimately leading to metabolic dysfunction. So sleep deprivation, stress reduction—all part and parcel of the same metabolic toxic mix. So does sleep affect your CGM, and the answer is: at Levels we’ve shown that the more sleep people get, the more time in range, the lower glucose excursions we see. More sleep, more better from a glucose standpoint.

[00:00:00] if you fix your diet, your improvement in cardiovascular mortality risk is dropped by 35 to 40%.

[00:00:16] Compare that to if all of a sudden you started exercising. Now that’s also good. The data show that if you start exercising, you’re Improvement in cardiometabolic mortality risk reduces by a total of 25%, which is better, 35 to 40 percent or 25%? Both good! Do both! If you had to do one thing, make a diet.

[00:00:46] Because number one, you have complete control. And number two, you can make your own food. And number three, it works best.

[00:00:59] Ben: So in February of 2024, Dr. Robert Lustig and I found ourselves sitting across from each other in Los Angeles. had planned to sit down and have a little chat about metabolic health and some of the implications around lifestyle, sleep, exercise, all these pillars of metabolic health. When we ended up sitting for six hours, we had a really deep conversation and we covered a number of topics.

[00:01:26] Ben: The idea was that we were filming some videos, some short form videos, which would be helpful for Levels members and anyone interested in metabolic health generally to get more insight into some snippets, some takeaways of what they could think about certain categories of metabolic health. Well, we decided to cut these into a podcast as well.

[00:01:46] Ben: So we’ve got a number of topics and we thought, why don’t we categorize them and people can pick and choose what they want to listen to. So lots of good information, lots of soundbites here, but we stitched them together into these different categories. So, there’s some transitions, but it might be something that is of interest.

[00:02:02] Ben: So the idea is always, I hope it helps people to learn more, to take metabolic health into their own hands In this episode, Rob covers exercise and lifestyle.

[00:02:13] Ben: How does exercise impact things like glucose? Are things like saunas tied to metabolic health and overall metabolic benefits? What are some lifestyle choices that people can make that will impact their metabolic health? And then how do things like sleep and even cortisol impact metabolic health overall?

[00:02:30] When you exercise, you activate the sympathetic nervous system. Now, the sympathetic nervous system is the part of your nervous system that is the fight or flight response. In the process, the sympathetic nervous system will activate and will send nervous impulses to the liver. The liver will then release all of the stored up glucose that it has in the form of glycogen.

[00:03:00] Glycogen is what you make In response to eating a meal, especially a high carbohydrate meal, glucose for a rainy day. This is why marathoners carb load before a race. Because they’re trying to build up their liver glycogen stores. So that they can release them during the race.

[00:03:27] When you start exercising, your liver will take that glycogen and turn it into glucose and release it into the bloodstream. That will lead to a rise in your serum glucose. That will lead to a glucose spike. And then that glucose is now available for muscles, for the brain, for the kidneys, to be able to metabolize energy while you are exercising.

[00:03:56] And it will stay up until either the liver runs out of glycogen, which takes about three hours. or until you stop exercising. In either case, your glucose will then fall precipitously. So if you stop exercising, you will clear that glucose spike very rapidly. If you are on the football gridiron and exercising like crazy, your glucose will start falling precipitously and you will all of a sudden become very tired because you have run out of glucose.

[00:04:36] of readily available glucose. This is one reason why the sports drink companies put fructose into the sports drinks, because that’s another way to generate glucose when you’re exercising. And it’s true if you are a you know, gridiron athlete, an elite athlete, that fructose in that sports drink will ultimately get converted back into glucose and will help replete the glycogen that your liver has lost.

[00:05:12] No one else needs the fructose for anything else. But the bottom line is you will clear the glucose spike rapidly because you have stopped exercising.

[00:05:27] What happens to your glucose when you enter a sauna? The heat is a stress. The stress activates the sympathetic nervous system. The sympathetic nervous system goes to your liver and causes glycogen to be released. And so it will generate a glucose spike all by itself with having eaten nothing. Just from the epinephrine being released, it will cause a glucose rise.

[00:05:58] That glucose will clear quickly, because your insulin will come up to meet it, and it will go away. It will have caused no damage, and will be gone very quickly. But that’s also one of the reasons why after you’ve been in the sauna, you want to go take a nap afterwards. It’s because you have actually depleted some of your glucose stores, and you need time to replete them.

[00:06:23] So, enjoy your nap.

[00:06:26] We’ve gotten sick in the last 50 years because of the changes in our environment. And our environment has changed in multitudinous ways. Our diet’s changed. Our sleep cycle’s changed. Our capacity and opportunities for exercise have changed. Our stress has changed. Our exposure to toxins has changed.

[00:06:53] Bottom line, we’re sick. In order to achieve optimal metabolic health, we have to work in every single one of those venues. How do we do that? Well, we can’t. We can’t fix them all. But there are certain ones that we can, okay? And the one that’s immediately available, and the one you can fix today, is your diet, and the data show that if you fix your diet, your improvement in cardiovascular mortality risk is dropped by 35 to 40%.

[00:07:35] Compare that to if all of a sudden you started exercising. Now that’s also good. The data show that if you start exercising, you’re Improvement in cardiometabolic mortality risk reduces by a total of 25%, which is better, 35 to 40 percent or 25%? Both good! Do both! If you had to do one thing, make a diet.

[00:08:06] Because number one, you have complete control. And number two, you can make your own food. And number three, it works best.

[00:08:18] Cortisol is the stress hormone. It is made by the adrenal gland and it circulates in the bloodstream. And what it does is raises the serum glucose in order to provide more energy for the brain so that the brain can still run, even when there’s no glucose available, and also it will start actually taking away from muscle.

[00:08:48] It will actually cause the dissolution of muscle in order to keep the brain fed. So chronic stress is the opposite of acute stress in terms of the physiology and in terms of the glucose requirement. The goal of chronic stress is to feed the brain because The brain is the highest glucose demander. It requires the most glucose all the time because it doesn’t have a place to store glucose.

[00:09:23] So cortisol lifts energy from the rest of the body and make sure that the brain gets it. Well, that has negative effects on the brain and it also has negative effects on that glucose excursion because glucocorticoids, Actually interfere with mitochondria and interfere with the ability to produce ATP in many of those organs.

[00:09:52] And so cortisol dissociates the energy availability from the energy utilization. It actually inhibits mitochondrial function. And so the higher the cortisol, the bigger the glucose rise. But the less well you’re going to clear it. Because glucose interferes with mitochondria, you see the effect as insulin resistance.

[00:10:19] In fact, the more stressed you are, the higher your fasting insulin, because the less well your mitochondria are working. And the only way to fix that is fix the stress. That’s pretty hard to do.

[00:10:36] It’s not a shocker that adults and children today are getting less sleep than they did before. In fact, 35 percent of adults get less than seven hours of sleep per night, and 23 percent of adults are chronic insomniacs. And the question is, what does that do to your metabolic health? And the answer is, It does two things, both bad.

[00:11:05] The first is it’s a stress. It raises your cortisol. And we’ve already talked about cortisol being a mitochondrial dissociator. It basically creates heat instead of creating ATP. That’s bad for your metabolic health because now your cells are basically running on empty. No wonder you feel lousy. Second, sleep deprivation increases It’s a hormone that is responsible for hunger, which comes from the stomach called ghrelin.

[00:11:39] Ghrelin is released in response to sleep deprivation, circulates in the bloodstream, goes to your brain and says, I’m hungry, feed me. And so you end up eating more, which will only raise your glucose excursions and your insulin response and generate increased fat and of course, chronic metabolic disease.

[00:12:02] So chronic sleep deprivation. affects cortisol, driving metabolic dysfunction, and ghrelin, driving increased eating. Everyone thinks, oh, I’m eating more because I’m up longer. No, you’re eating more because your ghrelin is dysfunctional. How do you fix sleep deprivation? Well, one way is cut the caffeine, because caffeine is exactly what’s wrong with sleep.

[00:12:33] But that’s not the only thing. The other thing to do is take the screens out of your bedroom. Studies show that children who sleep with their phones charging in their bedroom get 28 minutes less sleep per night than children whose screens are charging outside their bedroom. The blue light, by itself, alters your sleep.

[00:12:55] The, uh, diurnal rhythms of the brain, ultimately leading to metabolic dysfunction. So, sleep deprivation, stress reduction, all part and parcel of the same metabolic toxic mix. So, does sleep affect your CGM? And the answer is, at levels we’ve shown that the more sleep people get, the more time in range and the lower the glucose excursions that we see.

[00:13:27] More sleep, more better, from a glucose standpoint.