This Is Why You're Still Tired, Even When You Eat Healthy | Dr. William Li

1. 0:00 – 0:37

   Eating in vs. eating out: tuning in to how food makes you feel

   1. RCDr. Rangan Chatterjee0:00

      I love eating out as much as the next person, Dr. Li, but I will say that I've become a lot fussier these days, and I actually prefer eating in. I much prefer eating in because when you really tune into what good quality food tastes like, often when you're out, not always, there are some great restaurants out there and great cafes for sure, I just don't feel that good afterwards a lot of the time when I go out. It could be the oils they're using to fry or whatever it might be. So again, I'm not saying that applies to anyone else, but for me, I much prefer to eat in these days when I can.

2. 0:37 – 3:09

   Self-compassion around diet: guidelines, not a “religion”

   1. WLDr. William Li0:37

      I, I totally agree. And, and by the way, I think the, the, the companion piece that I add, 'cause I'm like you, I, you know, I sort of, I, I, I try to find what makes me feel good, uh, and, and stick to that. But I also think that, you know, having some self-compassion is an important-

   2. RCDr. Rangan Chatterjee0:58

      Yeah

   3. WLDr. William Li0:59

      ... component to that as well. So if you've decided that you're gonna just try to be as healthy as you can, um, don't feel like it's a strict religion or a s- you're not in a military camp where you can-

   4. RCDr. Rangan Chatterjee1:11

      Yeah

   5. WLDr. William Li1:11

      ... only do one thing. We're all human. We have to enjoy ourselves. We have to have enough compassion to realize that it's okay every ni- every now and then-

   6. RCDr. Rangan Chatterjee1:22

      Yeah

   7. WLDr. William Li1:22

      ... to, you know, kind of wander off the path. As long as you get back on the path, you're gonna be just fine. And I try to kind of lower people's stress level-

   8. RCDr. Rangan Chatterjee1:30

      Yeah

   9. WLDr. William Li1:30

      ... in trying to live a healthy life by also saying, "You know, look, these are guidelines. Y- you know that they're good for you. You, you should feel, you should feel better when you're doing them. Um, it's up to you to actually take that path." And, and rather than make people feel fear, guilt, shame when it comes to food, I try to give people permission to live a little, you know?

   10. RCDr. Rangan Chatterjee1:51

       Yeah.

   11. WLDr. William Li1:51

       Every now and then, you're gonna do something you're gonna really enjoy. Listen, if you spend more time doing things that are good for you, your body's gonna be strong enough to be able to rebound from something occasionally you do that's not so good for you. It's like driving on a road, right? I mean, look, you know the rules, following the rules of the road are actually gonna help keep you a safe driver so that you're gonna be accident-free. But look, who doesn't speed every now and then? And you know speeding can kill you, right? So, but every now and then, you need to get some place quickly.

   12. RCDr. Rangan Chatterjee2:20

       Yeah.

   13. WLDr. William Li2:20

       You're gonna go a little bit faster than the speed limit. It's okay.

   14. RCDr. Rangan Chatterjee2:23

       Yeah.

   15. WLDr. William Li2:23

       It's okay. And so I, I kind of try to give people permission to, um, and I encourage them to be self-compassionate and give them permission to feel the liberty to choose-

   16. RCDr. Rangan Chatterjee2:34

       Yeah

   17. WLDr. William Li2:34

       ... with the en- with the encouragement to make more good choices more often.

   18. RCDr. Rangan Chatterjee2:39

       Yeah, I completely agree. It's a great point, and j- just to be super clear, I've only got to that point about eating in compared to eating out, I would say in the last couple of years. You know, I've been on this journey to improve my health with my lifestyle for, you know, 10-plus years now. So you start off where you can, and bit by bit, that builds, and you go off track, and you go, "Ah, you know what? I actually feel better when I'm like this." And you know, last week, I was away for work between Monday, uh, afternoon and Friday evening, so all my

3. 3:09 – 6:08

   Why blood vessels matter: the body’s 60,000-mile delivery network

   1. RCDr. Rangan Chatterjee3:09

      meals were out. And I was completely fine, and I was able to function and d- and do what I had to do. But since I got back at the weekends, I'm like, "No, no, no, I just wanna eat in." I cook my own food now. So I think that's a really, really important point. You mentioned, uh, blood vessels before in relationship to olive oil. Now, we've spoken a lot about stem cells.

   2. WLDr. William Li3:30

      Hmm.

   3. RCDr. Rangan Chatterjee3:30

      If we could just shift the focus to blood vessels, olive oil is a food that can help us with our stem cells and help us with our blood vessels.

   4. WLDr. William Li3:41

      Hmm.

   5. RCDr. Rangan Chatterjee3:41

      Let's just set the scene again like we did with stem cells. Why is the health of our blood vessels so important? What do we get wrong when we think about blood vessels? And then how can we choose specific foods that, that are gonna enhance the health of those blood vessels?

   6. WLDr. William Li4:00

      Okay. So I mentioned earlier 60,000 miles worth of blood vessels-

   7. RCDr. Rangan Chatterjee4:05

      Yeah

   8. WLDr. William Li4:05

      ... are packed into our adult bodies. That is so extensive that if we were to pull out all the blood vessels and line them up end to end in your body, you'd actually form a line, a thread, that would wrap around the Earth twice. All right? And these literally are the highways and byways of everything, oc- oxygen we breathe, the nutrients that we eat, they deliver to every single organ in your body. Really, really critical. And in fact, no matter what you, e- else you think about, uh, in terms of your health, if your blood vessels are healthy, you are at a really great starting point to optimize the rest of your health. But if your blood vessels are unhealthy, you're gonna be far behind. In fact, it'll be impossible to optimize your health in any other part of your body. And this is true when you're a child. This is true when you're a young adult. This is especially true as we get older, like 40 and above. We need to start paying super attention to how well our blood vessels are functioning. Now, the good news, and what people don't get right sometimes, is that- Are you tired of waking up exhausted even when you've technically had enough sleep? Do you feel like you're constantly doing everything right, yet you still feel stuck? You're not broken. You're just running the wrong habits. I've taken everything I've learnt from helping thousands of patients and boiled it down into five tiny daily habits that can transform your life in just 30 days. No overwhelm, no pressure, just small shifts that reset your energy, mood, and mind. If you're ready to stop surviving and start feeling like yourself again, download my free guides now. Just click on the first link in the description box below or scan the QR code on screen. You've got absolutely nothing to lose except the version of you that's been running on empty for far too longWe

4. 6:08 – 7:34

   Blood vessels aren’t passive plumbing: the dynamic endothelium

   1. WLDr. William Li6:08

      think about our blood vessels as passive and like plumbing, and then they get clogged, they get narrowed with lipids or plaque or atherosclerosis, you know, and this is what ultimately leads to a heart attack or a stroke or for, you know, leg dysfunctions when you've got clogged arteries in your legs. "My arteries are hard." You hear this all the time. Well, our blood vessels are anything but static. It's not just piping under your sink that if you keep pouring grease down the sink, it's gonna clog up, uh, your, your, your sink, and then you gotta call the plumber in to, to o- open it up with a wire. Nope. It's not like that at all. Our blood vessels are incredibly dynamic, and that-- what that means is our body manages to maintain our blood vessels to try to keep them optimized all the time. Now, something that keeps our blood vessels healthy and dynamic is the inner lining of the blood vessels. Our blood vessels have a sleeve in it. It's like a layer of, um, plastic wrap-

   2. RCDr. Rangan Chatterjee7:08

      Mm

   3. WLDr. William Li7:08

      ... that is extraordinarily slippery. We call it the endothelial layer. Um, if you think about like a, a garden hose, and you were to cut the garden hose in half and look down the middle of the hose, you're looking down into the hole, and, and if you were to actually take, um, plastic wrap, the kind that you would have in your kitchen, and coat the inside of the garden hose with the, with the plastic wrap, so that when water is running through-

   4. RCDr. Rangan Chatterjee7:32

      Hmm

   5. WLDr. William Li7:32

      ... that the water is slip- slipping through-

   6. RCDr. Rangan Chatterjee7:34

      Yeah

5. 7:34 – 9:42

   Ice rink & Zamboni analogy: how diet damages (or preserves) vessel lining

   1. WLDr. William Li7:34

      ... sliding through the plastic wrap. Now, imagine in your blood vessels that same kind of wrap made out of living tissue called, called vascular cells, blood vessel cells. It's extraordinarily slippery. So, so slippery that I give the analogy of, like, an ice skating rink. If you've ever been a kid-

   2. RCDr. Rangan Chatterjee7:51

      Mm

   3. WLDr. William Li7:51

      ... gone ice skating, I don't know, most-- many adults don't ice skate anymore, but if you're a kid, you might have had that experience. You know that when you get out on that ice, on the ice in a-- on the skating rink, it's really, really slippery. It's hard to actually keep your balance. All right? Um, and that's what the blood vessels need to be so that all the blood cells that-

   4. RCDr. Rangan Chatterjee8:09

      Mm-hmm

   5. WLDr. William Li8:09

      ... are winging through our body, they don't stick to the walls at all. They just keep on going, keep on going. You know, like it's, there's like traffic direction. Um, this is, this way to your liver.

   6. RCDr. Rangan Chatterjee8:19

      Mm.

   7. WLDr. William Li8:19

      This way to your eyes. This way to your brain. Okay. Now, you also know that, um, uh, if you're on a... And, and by the way, if you've ever been ice skating, you know that after the ice is cleaned, there's a machine that will polish the ice between sessions in the ice skating rink. It's called a Zamboni, uh, a machine. They drive over it. It heats the ice. There's a little, uh, brush underneath it that kind of polishes the ice. When the ice is new and newly polished, you could take a sweater, 'cause it's a little cold in the ice skating rink, and you can throw it on the ice, and the thing will glide. Your sweater will glide, it's so slippery, all the way across the rink to the other end. Now, after you have a hundred people skating on the ice for a session or after a hockey game, you know, where, where peop- the players are really scuffing up the ice big time, all right? When you come off the ice, if you were to throw that sweater on it again, it won't slide.

   8. RCDr. Rangan Chatterjee9:10

      Mm-hmm.

   9. WLDr. William Li9:10

      It'll just stick right to the ice. It'll just stay right there. So the s- so we, we, just like, uh, the ice skating rink, you want your blood vessels to be really, really polished and smooth flowing. And if you don't treat your blood vessels properly, and there's lots of things that can damage our blood vessels, high amounts of salt, high amounts of sugar, high amounts of, of unhealthy saturated fats scrape up the lining of our blood vessels. That's like, uh, you know, that's the difference between being able to have the sweater glide all the way to the end of the rink-

   10. RCDr. Rangan Chatterjee9:42

       Mm

6. 9:42 – 13:50

   Repair and renewal: stem cells, vessel maintenance, and angiogenesis

   1. WLDr. William Li9:42

      ... versus having the sweater stick to the ice. Now, when you have blood cells sticking to the ice, that's not good when, when, when that ice is your inside your circulation, because that stickiness can actually start to build up layers and layers and layers, and that's really how blood vessels get narrow. So one of the things your body tries to do is to use those stem cells we talked about earlier and to try to repair those areas of the ice where there, like a piece might have come off, and smooth it out again.

   2. RCDr. Rangan Chatterjee10:12

      One of the most important pillars for our health is, of course, nutrition. But I think because of our busy, stressed out lives, so many people are struggling despite their best intentions. So many patients over the years have told me that they know what they should be doing, but they're struggling to actually do it, and that's why I'm a fan of AG1. AG1 is a daily health drink that contains over seventy vitamins, minerals, and other ingredients that are designed to make nutrition really easy. It's been in my own life for over six years now. It's simple, it's tasty, it's convenient, and it forms a part of my morning routine. People will routinely tell me that taking AG1 regularly has improved their focus, their cognition, their energy. Some people even tell me that they drink less coffee when they're taking AG1. And there's research out there showing us that taking AG1 regularly can improve specific markers of your gut health, which is really good for your immune health. So if you're looking to upgrade your own nutrition in a simple, tasty, and convenient way, try AG1. To get a free bottle of vitamin D and five free travel packs, go to drinkag1.com/livemore.

   3. WLDr. William Li11:31

      So we can actually restore that healthy layer. It's very quite, it's very, um, amazingly dynamic. And when we need more blood vessels, our bodies can naturally grow them, uh, where they need to be grown, and then stop it when there's adequate blood vessels. And if there's too many blood vessels growing, our, our, our b- body can also trim the extra blood vessels so we don't have too many. It's like a landscaper that's looking at a golf course and s- and keeping maintaining a perfect golf course. "Hey, there's a couple of patches that need some more, uh, uh, grass." They'll actually put the seed in there-

   4. RCDr. Rangan Chatterjee12:06

      Yeah

   5. WLDr. William Li12:07

      ... uh, and grow it right up, so it looks perfect, and if there's... And, and if the grass grows too high, it'll just mow the lawn, so you wind up having just the right amount at all times. Not too few, not too many, just the perfect amount. That's how, um, our blood vessels are maintained. That process is called angiogenesis. That's how blood vessels grow and stay healthy.

   6. RCDr. Rangan Chatterjee12:27

      Yeah, it's such a beautiful image to think about the inside of these miles and miles of blood vessels inside our body as either being, you know, smooth and the blood can travel with no friction and no problem at all, or there could be bumps and lumps there, and it can be more difficult. And, you know, we don't naturally, I think many of us think about food and blood vessels, but we do think about our brain health, our cognition, our mood, our skin health, our immune system, without realizing that, wait a minute, what underpins all of them? Well, if you don't have healthy blood vessels, you're not gonna be delivering oxygen to all of those critical things. So healthy blood vessels mean a healthy heart, a healthy brain. I, I think it's, um, it's such a core tenet of optimal health to have healthy blood vessels. Of course, many people talk about exercise and actually moving your body is gonna help, um, maintain those blood vessels or, or certainly it's one factor. But I've heard you say in one interview that one of your pet hates is when you hear about exercise being the only thing that's good for your heart's health because, of course, the food you consume is also very important with these blood vessels as well. So perhaps you can give some examples of what kinds of foods directly impact the health of our blood vessels.

7. 13:50 – 15:25

   Food and vascular health: olive oil, olives, and leafy greens

   1. WLDr. William Li13:50

      Well, one thing we talked about already is olive oils, uh, uh, olive oil, but I also wanna actually back that up and just say, look, and what about olives? You can just eat the whole olive, and now you get the fiber from the olive-

   2. RCDr. Rangan Chatterjee14:01

      Mm-hmm

   3. WLDr. William Li14:01

      ... and you'll actually get the other polyph- more polyphenols from the flesh of the olive. Uh, other things that... Other foods that are, um, clearly very health- heart-healthy are the leafy green foods that have dietary fiber and all these other polyphenols, so the Brassica family. Now, I like to cook, so, you know, when you get me talking about foods, I, I'll usually start talking about the foods. And most people think about broccoli, okay? Um, uh, I will tell you broccoli, like other Brassica veg- family of vegetables, have isothiocyanates. These are the class of molecules that create sulforaphanes, and sulforaphanes, um, are great for our metabolism. They help to lower, um, uh, our, uh, burn down our harmful body fat. They lower inflammation-

   4. RCDr. Rangan Chatterjee14:43

      Mm-hmm

   5. WLDr. William Li14:43

      ... which is really, really critical. And many of the Brassica family of vegetables, you're talking about broccoli, you're talking about kale, you're talking about Brussels sprouts, you're talking about bok choy, you're talking about Swiss chard. You know, I mean, these are, uh, vegetables that are growing in the summer gardens and, you know, take a little extra olive oil, saute some garlic on it, and just, just throw the vegetables in there, um, hit them with a little bit of, uh, spice, and you've got very quickly a delicious, uh, uh, warm, cooked vegetable dish, uh, that, that's tasty. Squeeze a little lemon. You want a little red pepper flakes.

   6. RCDr. Rangan Chatterjee15:16

      What is that doing for our blood vessels? If we... I mean, that sounds delicious. My stomach's-

   7. WLDr. William Li15:20

      Yeah

   8. RCDr. Rangan Chatterjee15:20

      ... watering already at the thought of that. But what, what does that actually do to the, to our blood vessels?

8. 15:25 – 17:43

   How leafy greens protect vessels: oxidative stress, inflammation, and fiber-driven benefits

   1. WLDr. William Li15:25

      What's happening is that they're-- When you're eating it, when you're eating that delicious food, the, the polyphenols and the sulforaphanes get absorbed into our bloodstream, all right? Uh, from your stomach. Uh, and those, uh, those, the, they, they serve a number of functions that help protect our heart. Number one, they lower oxidative stress. Uh, while there's-- whi- while these molecules are coursing through your blood vessels, 'cause they've been absorbed, uh, after you've eaten them from your stomach, they're protecting the walls of your blood vessel from damage. So if there's oxidative stress, they actually protect your cells, the lining, the, the, the smooth lining of your blood vessels. Number two, they actually lower inflammation as well. So, uh, the, the, the, the sulforaphanes in, uh, leafy greens lowers inflammation. Inflammation itself can damage the ice. They can scrape up the lining of the blood vessels. Lowers inflammation. Uh, uh, the other thing about these leafy greens is they have dietary fiber, which don't get absorbed into your bloodstream, but that tumbles all the way down through your gut, down to your gut microbiome.

   2. RCDr. Rangan Chatterjee16:26

      Mm-hmm.

   3. WLDr. William Li16:26

      We haven't had a chance to talk about that yet. But gut health, turns out feeding dietary fiber from our food to our healthy gut bacteria leads our own bacteria, healthy gut bacteria, to produce, um, substances, short-chain fatty acids-

   4. RCDr. Rangan Chatterjee16:43

      Mm-hmm

   5. WLDr. William Li16:43

      ... that then lower inflammation further. Inflammation is super damaging to our blood vessel health, right? So if you have-- If you're inflamed, and you've got inflammatory markers, I mean, we can measure, uh, in the lab, if you take a vial of blood, you measure your C-reactive protein as a marker for inflammation. Listen, that's, that inflammation, if your CRP, if your levels of inflammatory markers are high, you got inflammation everywhere in your body-

   6. RCDr. Rangan Chatterjee17:09

      Mm-hmm

   7. WLDr. William Li17:09

      ... including in the lining of your blood vessels. That's sixty thousand miles worth of inflammation. That's actually a really bad thing to be carrying around. So this is how leafy greens with their polyphenols and their dietary fiber can all conspire in a beneficial way or collaborate in a beneficial way to be heart healthy-

   8. RCDr. Rangan Chatterjee17:28

      Mm-hmm

   9. WLDr. William Li17:28

      ... starting with improving the healthier blood vessels.

   10. RCDr. Rangan Chatterjee17:31

       Yeah. Super interesting. Any, any other foods that we forget about when thinking about our blood vessels that you would like to highlight and encourage us to bring into our diets?

9. 17:43 – 20:32

   Tea and coffee as vascular-supporting beverages (plus synergistic daily patterns)

   1. WLDr. William Li17:43

      Yeah. Well, you know, it turns out that two beverages, tea and coffee, have polyphenols that are heart healthy and beneficial. All right? Uh, tea has catechins, and the specific catechin that has been best studied is called EGCG, epigallocatechin-three-gallate. Uh, and again, I encourage people not to get, uh, hung up on the technical stuff unless you're a science geek, but, um, just know that we, we know these things. Uh, in coffee, there's many different polyphenols. One of the best studies called chlorogenic acid.

   2. RCDr. Rangan Chatterjee18:16

      Mm.

   3. WLDr. William Li18:17

      Um, and both of these are heart-healthy and blood-- vascular-healthy, blood vessel-healthy, uh, for similar reasons. They protect your blood vessels against oxidative stress. They, um, lower inflammation.

   4. RCDr. Rangan Chatterjee18:28

      Yeah.

   5. WLDr. William Li18:28

      They're good for gut health. They improve your metabolism by helping your body burn down harmful excess body fat, which then contributes to inflammation. So, um, uh, so it-- they're, they're powerful levers-

   6. RCDr. Rangan Chatterjee18:41

      Yeah

   7. WLDr. William Li18:41

      ... that can actually help us, uh, in-- And if you-- By the way, if you combine thisOver the course of the day with eating some leafy greens, and, uh, and, and then you have some of these blood vessel regenerative foods like the barley with the beta-glucan or the mushrooms, um, that, that we talked about earlier, or a little bit of dark chocolate, high quality dark chocolate. You see, it's the net consumption-

   8. RCDr. Rangan Chatterjee19:03

      Yeah

   9. WLDr. William Li19:03

      ... of the things that we're eating all day long that expose our blood vessel, that extraordinary network, to help u- us maintain the roads in our body-

   10. RCDr. Rangan Chatterjee19:14

       Yeah

   11. WLDr. William Li19:15

       ... and that's our circulation.

   12. RCDr. Rangan Chatterjee19:16

       You mentioned some of the benefits of green tea there. I know you often speak about these drinks that, you know, all the longevity populations consume tea, coffee, and water. You also made a video recently on your YouTube channel about drinks that we can consume that help us with our metabolism and help us perhaps remove visceral fats from, you know, organs like the liver. It's quite an interesting concept, that, for people because I think if most people think about their weight and excess fats that may have built up on their body, I think there's a widespread view out there that the main thing that matters is being in some form of calorie deficit. So essentially, you are consuming less than you're burning off. So over time, you start to lose some of that excess fat. Now, I know your, your last book covered this in a lot of detail, but just help us understand how important what I just said is versus particular drinks like green tea or coffee that can really help boost our metabolism. Can you help us sort of find a way through that in case anyone's getting confused there?

10. 20:32 – 21:08

    Beyond calories: the ‘hidden trigger’ for fat burning

    1. WLDr. William Li20:32

       Yeah. There's a lot of ways to help our body optimize its metabolism. We, we talked about one earlier, which is don't overconsume calories, and whatever you do consume, uh, make it high quality. So that kind of z- that snapshot can captures a lot [chuckles] of what we talked about earlier. But, you know, there is a hidden mechanism, a hidden trigger in our body that can help burn down extra harmful body fat that, um, allows us to eat foods in order to burn fat. Now, that sounds like a contradiction in terms, right? If you wanna lose fat, you wanna not eat, right?

    2. RCDr. Rangan Chatterjee21:08

       Mm-hmm.

11. 21:08 – 24:37

    Cold exposure and brown fat: why cold plunges can boost metabolism

    1. WLDr. William Li21:08

       Nope. Actually, there are some foods, and this is a big surprise, and I wrote about this in my book, Eat to Beat Your Diet. There are some foods that actually trigger fat burning. Now, now to, to-- before I tell you the foods, I gotta tell you how this works. You know, um, [lip smack] uh, the popular, uh, fad that people have been doing these days, like cold plunges, right? And cold plunges being, uh, a healthy for your metabolism and other things. Well, actually, it does work, and I'll tell you why it works. When you expose your body to cold, it-- the temperature drop actually triggers, uh, a special kind of body fat that's not harmful, but really beneficial, and it's called brown fat. And brown fat is not a fat that most people are familiar with. Most people are familiar with, um, white fat. We call it white fat. They're two different color... Th-this is what these-- this is what this tissue looks like under the microscope, okay? White fat looks white under the microscope if you're in a lab, and brown fat looks brown-

    2. RCDr. Rangan Chatterjee22:07

       Mm

    3. WLDr. William Li22:08

       ... uh, under the microscope. White fat is the, uh, h- is sort of the fat that we normally think about. It's lumpy, bumpy, wiggly, jiggly. It can be under the skin, subcutaneous white fat. It's under our arms, under our chin. It's the muffin top that people don't like or the thigh fat or butt fat. Okay. But white fat is also, uh, not only under the skin, but it's packed inside the tube of our body. Our body's a tube. So i- if you look inside the tube of our body, um, where our organs are, our gut, our viscera. If fat growing there, called visceral fat, can be extraordinarily dangerous-

    4. RCDr. Rangan Chatterjee22:44

       Mm

    5. WLDr. William Li22:44

       ... because as it expands, it sort of expands like a glove wrapping around your organs, and it can be highly inflammatory.

    6. RCDr. Rangan Chatterjee22:50

       Mm.

    7. WLDr. William Li22:51

       And that it-- when-- and so our body's kind of evolved a natural way to tame that kind of extra visceral fat, and it's through brown fat. There's other kind of fat. Now, brown fat is not lumpy, bumpy, wiggly, jiggly. Brown fat is thin as a sheet, and it's not n- it's not close to the skin. In fact, it's close to the bone.

    8. RCDr. Rangan Chatterjee23:12

       Mm.

    9. WLDr. William Li23:12

       It's like, it's like attached to the muscle deep underneath your skin, and we got a little bit on the side of our neck, we have a little bit under our breastbone, we got a little bit between our shoulder blades, and it's scattered in our belly a little bit, all right? And what brown fat does, it just kinda hangs out quietly in the background. But if there's really cold temperatures, okay, cold temperatures will trigger it to fire up and generate heat, right? Um, uh, and, and, uh, when it generates heat, this, this evolved in animals, uh, who are-- that are hibernating, right? You get that woodchuck-

    10. RCDr. Rangan Chatterjee23:47

        Mm

    11. WLDr. William Li23:48

        ... gets, uh, nice and fat in the fall and into the winter, and then it waddles into the cave, and then it's not coming out. It, it's gotta stay warm in the winter. Why doesn't it freeze to death? Well, because the brown fat of those hibernating animals, when the w-weather gets really cold, triggers thermogenesis, thermal heat, genesis, generating heat, and that brown fat actually fires up and keeps the animal warm all winter long, provides it energy. Where does it get the energy from? The brown fat in hibernating animals has to, uh, sustain the heat-making fuel. Okay, the fuel. We'll talk about fuel again. It draws it down from the white fat. So that's why animals start the winter hibernating as big, round, you know, fat balls, and by the time spring comes around, they've consumed most of the energy, they've lost most of that fat-

    12. RCDr. Rangan Chatterjee24:37

        Mm

12. 24:37 – 26:18

    Evidence and seasonality: PET scans revealing brown fat activity

    1. WLDr. William Li24:37

       ... by generating heat. Well, guess what? Humans also have that same mechanism. In fact, it wasn't until 1930s, uh, before-- until we realized that humans also have brown fat.And it's in the locations I mentioned, around your neck and behind the breastbone and so on and so forth. Cold weather will actually fire it up. And we discovered this, by the way, it was published in the New England Journal of Medicine, um, in an analysis of PET scans. Now, PET scans pick up metabolism.

    2. RCDr. Rangan Chatterjee25:05

       Mm-hmm.

    3. WLDr. William Li25:05

       When you're generating heat, when brown fat's generating heat, it'll actually light up because of the higher metabolism. It was picked up in PET scans, um, uh, in New England, which is an area in the United States that gets cold winters. Um, and, uh, people were just-- were looking for, um, uh, uh, uh, tumors, and they found in- instead of a tumor, they found, um, something lighting up in the body that turned out to be brown fat. Uh, it wasn't a tumor, it was brown fat. People hadn't noticed it before. No one had noticed it before. But then when they actually looked at when PET scans showed the brown fat firing up, it was only during scans taken in people who were getting the scans in the winter-

    4. RCDr. Rangan Chatterjee25:47

       Mm

    5. WLDr. William Li25:47

       ... not in the summer. And so seasonally, our brown fat lights up, which makes sense, just like those hibernating animals. So cold plunges actually are beneficial for your metabolism by firing up your brown fat to burn down your harmful white fat. So brown fat is good fat, burns down extra white fat, which is bad fat and visceral fat, and lowers inflammation. Now, temperature does it. That's pretty cool. There are some drugs that will do it. I don't recommend it because they, they all have side effects. But guess what?

13. 26:18 – 28:35

    Foods and drinks that activate brown fat: green tea and coffee (plus a memory trick)

    1. WLDr. William Li26:18

       It turns out that there are certain foods that you can eat that turn on brown fat and, uh, and, and cer- certain beverages. And two of them we talked about, green tea and, uh, uh, and coffee, uh, both contain the polyphenols that light up your brown fat to burn down harmful excess white fat. So the two beverages, and there's a whole other foo- bunch of foods as well, can actually help to stimulate your metabolism by lighting up your brown fat. One last thing I'll tell you that, that is-- that people will like, uh, I can't remember, which is the brown fat, which is the white fat. I'll tell you what, how you can remember brown fat. You know, people are talking about mitochondria now these days in the, in the health and wellness world. Well, mitochondria are the little tiny battery- batteries in our cells that give us energy. Um, I remember when I was in medical school, I'm sure, uh, you had a similar experience memorizing all the different parts of the cell.

    2. RCDr. Rangan Chatterjee27:13

       Yeah.

    3. WLDr. William Li27:13

       Man, there are so many different parts of the cell. How, how on earth are you gonna memorize them? So I always remember mitochondria as mighty chondria, these little tiny little things that are small but mighty, and they generate energy.

    4. RCDr. Rangan Chatterjee27:24

       Yeah.

    5. WLDr. William Li27:24

       And so brown fat has a lot of mitochondria, okay? The cell-- fat cells, and that's why they're able to generate the heat. They're like loaded with batteries, okay? And they, the batteries generate heat. They draw down the fuel from the white fat. Well, mitochondria have a lot of iron in them. Iron, the same kind of iron that you'd have in nails, like, you know, like for construction. Now, what happens when you take a bunch of silver nails and you stick them outside in your front deck for, uh, uh, a, a few days or a week? They're gonna turn brown-

    6. RCDr. Rangan Chatterjee27:55

       Mm

    7. WLDr. William Li27:55

       ... 'cause they oxidize, right? Rusty nails. And that's what actually happens in our brown fat, is that the iron attached to other mitochondria, and there's a lot of mitochondria, which means there's a lot of iron, all right? Gets oxidized, and it gets rusty, and that's why brown fat is brown and white fat doesn't have that. So that's the reason that there's white fat and brown fat.

    8. RCDr. Rangan Chatterjee28:15

       [outro music] If you enjoyed that short clip, I think you are really going to enjoy the full conversation, which you can check out here. [outro music]

Episode duration: 28:36