The Dr. Hyman Show - Why Fasting Isn’t A Fad: Discover The Surprising Health Benefits | Dr. Mark Hyman

Episode Date: November 8, 2024

Fasting isn’t just about skipping meals—it's a powerful tool to improve your health when done right. In this episode of “The Doctor’s Farmacy,” I tackle the most common myths about fasting a...nd dive into the science behind how it impacts your metabolism, hormones, and overall well-being. You’ll learn how to navigate different fasting methods, from intermittent fasting to time-restricted eating, and discover how they can help you burn fat, preserve muscle, and even boost longevity. View Show Notes From This Episode Get Free Weekly Health Tips from Dr. Hyman Sign Up for Dr. Hyman’s Weekly Longevity Journal This episode is brought to you Mitopure, Rupa University, Big Bold Health, and AG1. Support essential mitochondrial health and save 10% on Mitopure. Visit TimelineNutrition.com/Drhyman and use code DRHYMAN10. Rupa University is hosting FREE classes and bootcamps for healthcare providers who want to learn more about Functional Medicine testing. Sign up at RupaUniversity.com. Big Bold Health is offering my listeners 30% off their first order of HTB Rejuvenate Superfood Head to Bigboldhealth.com and use code DrHyman30. Get your daily serving of vitamins, minerals, adaptogens, and more with AG1. Head to DrinkAG1.com/Hyman and get a year's worth of D3 and 10 Travel Packs for FREE with your first order.

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Starting point is 00:00:00 Coming up on this episode of The Doctor's Pharmacy. You gotta start your first meal with protein. Protein will help you live longer, be healthier. And the key thing is when you break your fast and you eat protein, it turns on your body's capacity to stimulate the growth and the building up of new muscle. Not if you have sugar for breakfast. For me, being healthy means being able to get up
Starting point is 00:00:23 every morning and do exactly what I wanna to do, no matter my age. In fact, I recently hiked 15 miles in the snow in the mountains of Patagonia. I was sore and tired after, but so was my 28-year-old guide who was half my age. And that's why I'm excited to share a supplement that's been a game changer in my fitness journey. Timelines might appear. As you age your mitochondria, the tiny energy factories inside the cells of your muscles and organs become less efficient. And this can cause your energy levels and muscle function to wane, leaving you feeling too tired to do all the things you used to do and all the things you want to do. But MitoPure can help you turn back the clock.
Starting point is 00:00:53 It's clinically proven to rejuvenate and invigorate tired, worn-out mitochondria for improved energy, muscle strength, and endurance. It's backed by more than 15 years of serious science. And I can tell you personally that my workouts have never felt more productive with noticeable gains in muscle and endurance within just a few months of taking it. And right now, Timeline is giving my community an exclusive 10% off your first order of MitoPure.
Starting point is 00:01:13 Just head to timeline.com forward slash Dr. Hyman, that's D-R-H-Y-M-A-N, and start your journey to peak muscle health. It seems that every day, more and more patients come into my office bringing ever-increasing amounts of healthcare information with them. And I love it when this happens because it means people are taking ownership of their health, but it also means I have to stay on the top of my game.
Starting point is 00:01:31 So as a healthcare practitioner, how do you make sure that when a patient walks into your office and says, hey, I really want a Dutch Complete or a GI map, that you have the right answers and tools? The answer is Rupert University. They are the number one educational institute for root cause medicine with over 20,000 practitioners a year learning about functional and specialty lab testing. Not only do they have absolutely free live classes hosted every week, but they bring in industry experts to teach in-depth six-week boot camps on all the most popular functional tests.
Starting point is 00:01:57 If you want to level up your knowledge of functional lab testing, make sure to visit RupertUniversity.com. Before we jump into today's episode, I'd like to note that while I wish I could help everyone by my personal practice, there's simply not enough time for me to do this at this scale. And that's why I've been busy building several passion projects to help you better understand,
Starting point is 00:02:15 well, you. If you're looking for data about your biology, check out Function Health for real-time lab insights. If you're in need of deepening your knowledge around your health journey, check out my membership community, Hyman Hive. And if you're looking for curated and trusted supplements and health products for your routine, visit my website, Supplement Store, for a summary of my favorite and tested products. Welcome back to another episode of the Doctor's Pharmacy and Health Bites, where we take juicy little bites into current health topics. When it comes to fasting, there's a lot of misinformation floating around
Starting point is 00:02:49 and one of the most common myths is that fasting slows down your metabolism. But here's the truth, it all depends on how you fast. It all depends on how you fast. Long-term fasting can have its drawbacks like slowing down your metabolic rate as your body conserves energy or losing muscle. But when it comes to short-term fasting, the opposite is often true. It can actually give your metabolism a boost. In today's episode, we're diving deep into the science behind fasting and metabolism. We're going to break down the differences between long-term and short-term fasting, and we're going to explore how your body responds to each, and we're going to debunk some of the biggest myths out there. So whether you're curious about intermittent fasting or time-restricted eating, or just want to better understand how fasting
Starting point is 00:03:32 impacts your hormones, your energy levels, and overall health, well, this episode is packed with insights to help you make informed choices. So let's cut right to it. The first myth, myth number one, fasting slows your metabolism. Well, many people believe that fasting slows your metabolism, and this might be true in some extreme cases, but the truth is it depends on the type of fasting you're doing. Long-term fasting could have negative implications for your metabolism, but with short-term fasting, the opposite actually seems to be true. It actually seems to speed up your metabolism. So let's break it down. What is long-term fasting? Well, long-term fasts typically range from a full day to several days without food. Long-term fasts have
Starting point is 00:04:09 lots of benefits. It stimulates autophagy or cellular cleanup. It promotes the burning of fat, clean fuel instead of carbs for energy. And it can be super beneficial for weight loss, improving insulin sensitivity and lowering body inflammation. About 48 hours or more into a fast, your metabolism starts to shift. The body may start to conserve energy, which results in a downregulation of metabolism. Now, this is an adaptive response to prolonged calorie restriction. But because your body doesn't know when your next meal is coming, your metabolism slows to conserve energy. Now, why is long-term calorie restriction a problem? Well, over time, long-term calorie restriction without adequate nutrition causes your body to go into what we call starvation mode. And this puts stress
Starting point is 00:04:52 on your body. In most cases, a little stress isn't a bad thing. It can actually be a good thing. But prolonged stress is not necessarily good. Now, there's a concept known as hormesis. This is kind of a good stress. It's basically a stress that doesn't kill you but makes you stronger. And you get that with short-term fasting, with exercise, a sauna, cold plunge, and that turns on all your longevity switches. Now calorie restriction is a form of hormetic stress and it has its benefits. But there's also bad stress which occurs when we undergo this stress for too long, and a slower metabolism could be the result. So what caused your metabolism to slow down
Starting point is 00:05:28 during long-term fasts, during calorie restriction? Well, hormones change. Leptin and ghrelin change. During prolonged fast, your body undergoes changes in the appetite-suppressing hormone called leptin and the appetite-stim stimulating hormone called ghrelin or ghrelin or however you want to say it but basically that's the hormone. Leptin is a hormone that's produced by fat cells and helps regulate metabolism and hunger. Kind of tells you when
Starting point is 00:05:55 you're full. When calorie intake is restricted leptin levels go down and that tells your body that energy stores are low. Now this is a good thing for people who have a common condition called leptin resistance, which is when you basically have too much food and your leptin levels go up and up and you become resistant to the effects of leptin. And when you do fasting, it actually makes your leptin sensitivity better. So you're not resistant to its effects, which makes you feel full. And then that stimulates the body's ability to regulate your appetite more naturally. It also improves insulin sensitivity and leads to weight loss. Now, in the long term, in non-obese individuals, when you fast too long, it can result in a slow down of your metabolic rate. And that means you're going to try to conserve energy because
Starting point is 00:06:40 your body thinks you're starving. Well, ghrelin, which is the hunger hormone, will initially increase during fasting, making you feel hungry. Its job is to stimulate appetite and food-seeking behavior, which is a good thing. When you're hungry, you're going to go looking for food. Now, during longer fasts, more than a few days, then ghrelin levels start to decrease. And studies examining three-day fasts have found that 24-hour mean grain levels actually declined over the fasting period. In other words, you know, a lot of people who are fasting report a decreased hunger as you continue to fast. So you might be hungry the first few days, and then after a while, you're not hungry.
Starting point is 00:07:19 Now, when you're less hungry, you eat less, and the body then adapts by slowing down your metabolism. Now, another thing happens when you fast too long. Your thyroid doesn't work out so good. A slower metabolism is in large part related to your thyroid hormone level. See, thyroid is the master control center of your metabolism. When you undergo long-term fasts or calorie restriction for longer periods of time, it actually lowers your thyroid hormone production and therefore your resting metabolic rate, meaning you burn less calories just sitting around. T3 is the active thyroid hormone and it plays a really important role in regulating your metabolism.
Starting point is 00:07:56 During longer fasts, the body aims to conserve energy and the way it does that, it reduces the production of the active thyroid hormone called T3. So you don't burn as many calories. That slows your metabolism. Your body can conserve energy and become more efficient at using those fewer calories. Now, this is good when we didn't have a lot of food around and we conserved energy. And it was sort of built in to protect us from food scarcity. But we don't have that anymore.
Starting point is 00:08:21 Now, as your metabolism starts to slow down, the body becomes resistant to weight loss. And then it makes it harder to continue losing weight without further reducing calories. You get kind of a plateau. Now, of course, if you're not eating at all, your body's going to continue to waste and you'll starve and die. But if you calorie restrict, initially you'll lose weight, but then you hit a plateau. Now, it's a survival mechanism. It's going to help your body conserve energy in times of scarcity. Now, short-term fasting is good because it doesn't result in a slowed metabolism. It does the opposite. It actually boosts your metabolism. So what's short-term fasting? Well, there are many different types of short-term fasting. A few of the main ones include what
Starting point is 00:09:00 we call intermittent fasting. Now, that's an umbrella term for various fasting schedules where you alternate between periods of eating and fasting. There's a lot of different methods out there. There's something called the 16-8 method, which is 16 hours of fasting and eight hours of eating. So let's say you eat between, let's say, eight in the morning and four in the afternoon, right? And then you're done.
Starting point is 00:09:19 And then you take the next 16 hours off and you go to bed and you sleep and you wake up and you eat. There's something called the 5-2 method, which is eating normally for five days and dramatically reducing your calories for two days. Or there's alternate day fasting, or you can do even shorter fasts like 12 to 14 hours. Now, intermittent fasting focuses on more extended fasting periods, which may include skipping meals or limiting calorie intake for whole days. But I think the better way to think about this is what I call time-restricted eating. And it's a specific form of intermittent fasting that emphasizes eating all your daily meals within a consistent window
Starting point is 00:09:55 of time, like eight hours, 10 hours, and fasting for the rest of the day, like 14 to 16 hours. Unlike other forms of intermittent fasting, time-restricted eating focuses more on aligning eating with the body's natural circadian rhythms and ensures all meals are consumed within a set time frame each day. You can do 12-12 fasting, 12-hour feeding window, where all your calories are consumed, followed by the 12-hour fasting period where food intake is restricted. So basically you would be fasting after dinner from 8 p.m. to 8 a.m. the next morning. I mean, everybody could probably do a 14-hour fast. Basically you eat dinner and finish at, let's say, 6 o'clock.
Starting point is 00:10:33 That means you can eat breakfast at 8 o'clock the next morning. The calorie restriction is not a requirement. It can be a side effect of condensing your daily food intake to a shorter time window because you just don't have enough time to eat that many calories. And that's why time-restricted eating is so popular. It helps you eat fewer calories, which then leads to weight loss without having to change your diet. But optimizing your diet quality leads to even more benefits. We're going to discuss that later.
Starting point is 00:10:54 But there are some studies that show that regardless of what you eat, it works, but it works better if you eat more healthy food. Now, short-term fasting can actually reset and even boost your metabolism when you do it correctly. It does this by supporting fat burning and by supporting metabolic health. And it modulates several fat burning hormones, especially insulin. Now, high insulin levels block fat loss and it makes it harder to lose weight. And intermittent fasting can change that.
Starting point is 00:11:22 Now, insulin is the fat storage hormone. And when you have a high insulin level, you can't lose weight. And intermittent fasting can change that. Insulin is the fat storage hormone. And when you have a high insulin level, you can't lose weight and the fat gets locked in the fat cells. So you can't even burn them. Research shows that intermittent fasting can help lower your fasting insulin, which is especially meaningful for those with prediabetes or type 2 diabetes or those with underlying metabolic dysfunction. And that, my friends, applies to 93.2% of Americans. That means somewhere in that spectrum of mild insulin resistance to prediabetes to type 2 diabetes, 93.2% of Americans fall in that group, which is terrible. And most of us would benefit from listening carefully to this podcast and actually applying the principles here. And a big study, what we call a meta-analysis, which is a study
Starting point is 00:12:09 of other studies, found that intermittent fasting reduced insulin levels by an average of 13 milliunits per liter in patients with metabolic syndrome. And that is a lot. Okay, that's a lot. A review of the literature found that intermittent fasting and alternate day fasting could reduce fasting insulin levels in pre-diabetics by up to 31% after eight weeks. That's a good thing because high insulin levels lead to heart attacks, strokes, cancer, dementia, obviously diabetes eventually. Now, some studies have even shown that patients were able to reverse their need for insulin therapy just by therapeutic intermittent fasting when they're supervised by their doctor.
Starting point is 00:12:42 I've seen this over and over. When people eat healthfully, when they cut out sugar and carbs, when they narrow their eating window to 12 minimum, but ideally 14 to 16 hours, it has dramatic effects. The other thing that happens when you do intermittent fasting is you increase the level of something called norepinephrine, kind of like adrenaline, right? This is your stress hormone. It's involved in the fight or flight response. And when you intermittent fast, it increases adrenaline, which is a good stressor because it tells your body to mobilize stored fat to burn for energy, which is a good thing. It also stimulates human growth hormone, which is really important. It helps with fat loss and it helps you preserve muscle mass. Now, this brings me to another common myth about fasting. As you've heard me talk about,
Starting point is 00:13:28 I co-founded a company called Function Health, which gives you access to over 110 biomarkers for $4.99 membership a year. Now, when you want to see the impact of your fasting regimen on your hormones and biomarkers, you should for sure check out Function Health before and after you do your intermittent fasting regimens. And we're going to put the link in the show notes. But if you go to functionhealth.com forward slash mark, you can jump the wait list, which is about 300,000 people right now. So little tip for me. Okay, let's get into the second myth. Myth number two, fasting causes muscle loss. Your muscle is three times, maybe even more, metabolic active than fat and requires
Starting point is 00:14:06 a lot of energy to maintain it. Muscle contributes to about 20% of your total daily energy expenditure. For every extra one pound of muscle on your body, you burn six to 10 extra calories per day. So that's why strength training is so great. It actually makes you burn more while you're just sitting around doing nothing. If you heard me talk recently, you probably know how much I love Himalayan tartary buckwheat, a gluten-free seed loaded with longevity-promoting nutrients. My good friends at Big Bolt Health have been carefully growing and researching this ancient plant for years. After tons of positive feedback from me and thousands of customers, they produced the world's first 100% organic Himalayan tartary buckwheat sprouted powder. It's easy to digest, richer in vitamins and minerals, and contains up to 10 times more plant nutrients like rutin and quercetin. I love this as a topper in my yogurt, a sprinkle on savory meals, or as an easy add to my smoothies and protein shakes.
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Starting point is 00:15:40 I also trust AG1 because it's made with bioavailable ingredients, meaning my body can actually use the nutrients. And it's non-GMO with no added sugar. So this holiday season, try AG1 for yourself or even gift it to someone special. It's the perfect time to focus on supporting your body with an easy and surprisingly delicious daily health drink. And that's why I've been partnering with AG1 for so long. Every week of November, AG1 will be running a special Black Friday offer with a free gift for your first subscription. In addition, the welcome kit with vitamin D3 and K2. So make sure to check out drinkag1.com slash hymen to see what gift you can get this week. That's drinkag1.com slash hymen to start your holiday season off on a healthier note while supplies last. Now during prolonged fasting or
Starting point is 00:16:18 calorie restriction, the body actually breaks down muscle, which is not good, especially if you're not resistance training or if you're not eating enough protein. Now, this loss of muscle is not a good thing because then you get a slower metabolism since fewer calories are burned. And that's why I don't regularly do prolonged fasts. When I do this, I'm relatively thin, healthy, fit, don't have insulin resistance. I have to be careful because I will lose significant amounts of weight and muscle if I do too long fast. But I can do 12 to 14, sometimes 16 hours without a problem.
Starting point is 00:16:48 When you're fasting, you don't want to lose muscle. You want to build muscle and maintain your muscle, not lose it. Why? Because muscle is the organ of longevity. It's linked to a longer health span and your lifespan. When you have a lot of muscle, it's linked to a longer health span, meaning you're healthy longer and to a longer lifespan. And it does that through a lot of different mechanisms. It lowers the risk of something called sarcopenia, which means less muscle. And that's really this
Starting point is 00:17:13 hidden disease of aging that affects so many people. Basically turning your muscle from a filet mignon in your 30s to a Wagyu ribeye in your 60s or 70s, that's bad news. Even if you don't gain weight, you can lose muscle, stay the same weight, and you become basically skinny fat. Also, when you look at people who don't build muscle and strength training, they get osteoporosis, and you can get chronic diseases like obesity, Alzheimer's, type 2 diabetes. Now, when you have enough muscle, it helps protect against chronic disease by improving your metabolic health. It improves insulin sensitivity and muscle acts like a sponge. It soaks up sugar and excess fuel from your bloodstream. Now, having muscle also benefits your brain, which is kind of your
Starting point is 00:17:56 biggest muscle, not actually a muscle, but it's the thing that you use to run your life basically. And if it's not working well, it's a problem. And so having healthy muscle also leads to improved cognition, to mood, to mental health, and lots more. And that's why we got to combine resistance training with any time-restricted eating or intermittent fasting regimen to preserve muscle and get the maximum benefits. When you just do it without the strength training, I don't think it's a good idea. Body composition is really important. And this is really how much fat and how much muscle do you have, right? Very simple thing, but it's often not looked at.
Starting point is 00:18:30 It's one of the most important diagnostic tests we can do. Now, when intermittent fasting is combined with resistance training, meaning strength training, your lean muscle mass is also preserved, which is a good thing. Now, some studies suggest that resistance training while intermittent fasting improves body composition by increasing muscle mass and decreasing body fat. That's a good thing. And so this is really where we want to go. We don't want to fast and lose muscle because that's a bad thing. Now there's a randomized control trial of 41 overweight obese adults. They found that combining intermittent fasting with
Starting point is 00:19:02 calorie restriction and regular protein intake, about 25 to 50 grams per meal over eight weeks, led to greater reductions in total body fat, in visceral fat, in other words, the inflammatory belly fat, and total body weight compared to just calorie restriction alone. So the message here is if you're going to do calorie restriction or time-restricted eating or intermittent fasting, strength training is non-negotiable. Intermittent fasting in this study combined with time protein intake and calorie restriction positively shifted the gut microbiome to bacteria that help burn fat and improve your metabolic health more than just calorie restriction alone.
Starting point is 00:19:44 Yep, your gut bacteria actually affect your weight. It's quite remarkable. But you got to make sure you're getting enough protein. That's really key. And the ideal amount, if you're active, is about a gram per pound of ideal body weight. So if you're 120 pounds, that's about 120 grams a day. It can be 0.7 to 1, but somewhere in that range. And this really helps you fight muscle loss that happens during prolonged fast. Now, here's a tip. Break your fast with a meal that contains protein to halt the muscle protein breakdown from your overnight fast. And then you stimulate muscle protein synthesis.
Starting point is 00:20:18 So this is really important. I want you to hear this. When you fast, even if it's just overnight, right, from 12 hours, from let's say eight at night till eight in the morning, you got to start your first meal with protein. If you do what we do in America, which is eat sugar for breakfast, cereal, muffins, bagels, croissants, sweetened sugars, sweetened teas, sweetened coffees, I mean everything that we typically eat in America, it's going to kill you, I promise you, faster than if you eat protein. Protein will help you live longer, be healthier. And the key thing is when you break your fast and you eat protein,
Starting point is 00:20:57 it turns on your body's capacity to stimulate the growth and the building up of new muscle, not if you have sugar for breakfast. Fasting only becomes a problem for muscle mass if you're not substituting calories and carbs with protein and also adding resistance training. Okay, what's the third myth around fasting? Fasting increases the risk of heart disease. Well, there's been a lot of buzz around articles attempting to debunk the benefits of fasting. Some even link it to an increased risk of heart disease? Well, there's been a lot of buzz around articles attempting to debunk the benefits of fasting, some even linked it to an increased risk of heart disease, which doesn't sound so great. Now, one study in particular caused confusion by suggesting that time-restricted eating, specifically an eight-hour window, which is a 16-hour fast, right, was linked to a 91%
Starting point is 00:21:41 higher risk of cardiovascular death, according to the American Heart Association. So that sounds terrible. Now, for those with existing heart disease, the study claimed that eating in a window of 8 to 10 hours per day was associated with a 66% higher risk of death from a heart attack or stroke. But let's kind of wait there for a minute and break this down. Let's look at the limitations of the study, which were quite significant. First, the data came from about 20,000 US participants from what we call the NHANES study, which is the National Government Study, the National Health and
Starting point is 00:22:14 Nutrition Examination Survey. Dietary information was based on two self-reported questionnaires and relied on participants' memory, which is not really good. The data on dietary food frequency questionnaires shows that they're pretty unreliable. And there's a lot of bias, right? People often misremember what they ate. They underestimate what they ate. They overestimate the good stuff. They underestimate the bad stuff. Let's face it, we're all human and we don't like to tell the truth. So it's really not an accurate way to evaluate someone's diet. And there's just a lot of data on this. And I've written a lot about this, but it's something we need to really be aware of. These food frequency questionnaires can be helpful for looking at maybe patterns or associations, but they don't prove anything. Second, the study didn't account for what we call confounding factors that have influenced participants'
Starting point is 00:22:58 health or the decision to engage in time-restricted eating. In other words, maybe the people who tried to do this were already really sick. And so that's why they did it to improve their health, but they were already really sick and already had a high risk of heart attacks. And maybe it wasn't the time-restricted eating at all. The other thing was that overall diet quality wasn't really paid attention to. So, I mean, for example, some of the participants might do their fast, but then when they eat, they just eat the standard American diet or have fast food or French fries or sugar or crap, right? So is it fasting that caused the problem or is it the rest of their diet? And third, the researchers focused only on meal timing and cause of death. They didn't provide other health data such as things about
Starting point is 00:23:38 your critical health factors that determine your risk, like how many calories are consumed during the feeding window? What was the quality of the calories? Was it whole foods or was it the standard American ultra-processed diet, which is what we mostly eat in America? 60% of our diet is ultra-processed food. Of course, there's lifestyle factors that they didn't account for.
Starting point is 00:23:55 Stress, smoking, alcohol. Maybe the time of day they're eating is also important. Fasting during the day and binging at night is more problematic than eating during the day and fasting at night. In other words, what if you didn't eat all day and then you had a giant meal at dinner and then kept eating until you go to bed? That's going to have a very different effect on your metabolism. So this is the premise of time-restricted eating or eating within your circadian rhythm. While the headlines might sound scary, it's important to understand,
Starting point is 00:24:19 like any study, what the limitations are before you come to any conclusions. So is fasting dangerous for some people? Yes. True. Who are those people? Well, if you're pregnant, not a good idea. If you're breastfeeding, if you're trying to get pregnant, if you have thyroid issues, if you're type 1 diabetic, or you're underweight or malnourished, all those things, or you're frail, or you're elderly, or chronically ill, maybe not such a good idea. Now, fasting can trigger hormonal changes that cause your body to be stressed, not something you want while you're pregnant or trying to get pregnant. Women who are trying to get pregnant with PCOS, which is polycystic ovarian syndrome, or reproductive issues could benefit from time-restricted eating, or at least eating within a 12-hour window. I think that's
Starting point is 00:25:00 just basic. The standard should be everybody should take a 12-hour break from eating every day, right? Finish dinner at eight, don't eat till eight in the morning. Finish at seven, eat breakfast at seven in the morning. That's not so hard. That's why I call it breakfast, break fast, because we should be breaking the fast, not just eating until we go to bed and then eating first thing in the morning. Now, intermittent fasting can also help reset the body's internal clock. So what does that mean? Well this is your circadian rhythm. When you fast it's really important to fast with your circadian rhythm not against it. So what do I mean by that? Well human beings are biologically programmed to digest and absorb food best earlier in the day.
Starting point is 00:25:42 This is known as circadian eating. Dr. Sachin Panda is a lead scientist in circadian rhythm research. That means doing daytime things when the sun comes up, like eating, moving, and working, and nighttime things when the sun goes down, like winding down and sleeping. Duh, right? Dr. Panda discovered that thousands of genes turn on and off at specific times of the day, which affects lots of different bodily functions. Your circadian rhythm affects your body's ability to digest your food. Now, insulin sensitivity, which is really important, is highest in the morning and it decreases during the day. Our digestive system produces less saliva, stomach acid, and digestive
Starting point is 00:26:23 enzymes at night, which is why late night eating is a bad idea. And yet it's what we do mostly in America. What happens when you eat late? Well, it causes blood sugar swings throughout the night, makes weight loss harder, it messes up your REM sleep, which is your dream sleep, and increases the risk of type 2 diabetes. It also puts energy towards digestion, takes energy away from rest and repair. Because at night your body's supposed to rest and repair and heal, but when it's digesting, it can't do that. And time-restricted eating might also help extend your lifespan. A study on firefighters showed that 14-10 time-restricted eating, meaning 14-hour fast, 10-hour eating window, for six weeks improved oxidative stress and reduced something called advanced glycation
Starting point is 00:27:06 end products, which is a marker of aging, inflammation, and cardiovascular disease. Now eating an earlier dinner or fasting for at least three hours before bed can improve sleep, it can support weight loss, it can improve your immune function and your metabolic flexibility, and prevent chronic disease. So lots of benefits. So are the benefits of fasting due to not eating, to calorie restriction, or eating within your circadian rhythm? Well, it's probably a combo effect. So as we've explored today, fasting doesn't have to be a metabolism-slowing monster. It's often made out to be. When approached correctly, especially with short-term fasting methods like intermittent fasting, time-restricted eating, you can actually boost your metabolism. It can help you burn more
Starting point is 00:27:48 fat and it can improve your overall health. It's all about finding the right balance for your body and your lifestyle. So whether you're looking to improve your metabolic health, manage your weight, or simply give your body a reset, fasting can be a powerful tool when used wisely. The key takeaway, don't fall for the myths and understand the science behind fasting. Listen to your body. Your body is the smartest doctor in the room. I always say that. Don't listen to doctors. Don't listen to the science. See how you feel and how you respond and then learn from what your body is telling you. Also remember fasting is just one piece of a puzzle.
Starting point is 00:28:25 Combining with a nutrient-dense diet, with regular exercise, with stress management, it's going to give you the best results. Thanks again for joining me today on The Doctor's Pharmacy and Health Bites. Don't forget to rate, review, and follow The Doctor's Pharmacy wherever you get your podcasts. Stay healthy, stay informed, and I'll catch you next Friday for another episode of Health Bites. Thanks for listening today. If you love this podcast, please share it with your friends and family. Leave a comment on your own best practices on how you upgrade your health and subscribe wherever you get your podcasts. And follow me on all social media channels at Dr. Mark Hyman. And we'll see you next time on The Doctor's Pharmacy. For more information on today's episode,
Starting point is 00:29:02 please check out my new video and audio podcast, Health Hacks. It airs every Tuesday and includes a more detailed breakdown of these Friday Health Bites episodes. I'm always getting questions about my favorite books, podcasts, gadgets, supplements, recipes, and lots more. And now you can have access to all of this information by signing up for my free Mark's Picks newsletter at drhyman.com forward slash Mark's Picks. I promise I'll only email you once a week on Fridays and I'll never share your email address or send you anything else besides my recommendations. These are the things that have helped me on my health journey
Starting point is 00:29:33 and I hope they'll help you too. Again, that's drhyman.com forward slash MarksPix. Thank you again and we'll see you next time on The Doctor's Pharmacy. This podcast is separate from my clinical practice at the Health and Wellness Center and my work at Cleveland Clinic and Function Health, where I'm the chief medical officer. This podcast represents my opinions and my guests' opinions, and neither myself nor the podcast endorses the views or statements of my guests. This podcast is for educational purposes only. This podcast is not a substitute for professional care by a doctor or other qualified medical professional. This podcast is provided on the understanding that it does not constitute medical or other professional advice or services. If you're looking for your help in your journey, seek out a qualified medical practitioner. You can
Starting point is 00:30:13 come see us at the Ultra Wellness Center in Lenox, Massachusetts. Just go to ultrawellnesscenter.com. If you're looking for a functional medicine practitioner near you, you can visit ifm.org and search find a practitioner database. It's important that you have someone in your corner who is trained, who's a licensed healthcare practitioner, and can help you make changes, especially when it comes to your health. Keeping this podcast free is part of my mission to bring practical ways of improving health to the general public. In keeping with that theme, I'd like to express gratitude to the sponsors that made today's podcast possible.

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