Essentials: How to Control Hunger, Eating & Satiety

0:00:03 Welcome to Huberman Lab Essentials, where we revisit past
0:00:06 episodes for the most potent and actionable science based
0:00:09 tools for mental health, physical health, and
0:00:13 performance. I’m Andrew Huberman, and I’m a professor of
0:00:17 neurobiology and ophthalmology at Stanford School of Medicine.
0:00:20 This podcast is separate from my teaching and research roles at
0:00:24 Stanford. It is, however, part of my desire and effort to bring
0:00:26 zero cost to consumer information about science and
0:00:29 science related tools to the general public. Today, we’re
0:00:32 going to talk about how hormones impact feeding and
0:00:36 hunger, as well as satiety, the feeling that you don’t want to
0:00:39 eat or that you’ve eaten enough. Now, it’s important to
0:00:42 understand that hormones don’t work alone in this context. Today,
0:00:45 I’m going to describe some hormones that have powerful
0:00:48 effects on whether or not you want to eat more or less or
0:00:52 stop eating altogether. But they don’t do that on their own,
0:00:55 they do that in cooperation with the nervous system. The first
0:00:58 thing that you need to know about the nervous system side, the
0:01:02 neural control over feeding and hunger, is that there’s an area
0:01:05 of your brain called the hypothalamus. Now, the hypothalamus
0:01:07 contains lots of different kinds of neurons doing lots of
0:01:10 different kinds of things. There’s a particular area of the
0:01:14 hypothalamus called the ventromedial hypothalamus. And
0:01:17 it’s one that researchers have been interested for a long time
0:01:20 now, in terms of its relationship to hunger and
0:01:25 feeding. And the reason is, it creates these paradoxical
0:01:27 effects. What do I mean by that? What they found was that
0:01:30 sometimes lesioning or disrupting the neurons in the
0:01:33 ventromedial hypothalamus would make animals or people
0:01:38 hyperphagic, they would want to eat like crazy. And other
0:01:41 lesions in other individuals or animals would make them
0:01:44 anorexic, would make them not want to eat at all, it would
0:01:47 make food aversive. So that means that the ventromedial
0:01:50 hypothalamus is definitely an interesting control station for
0:01:53 hunger and feeding and satiety, but it doesn’t really tell you
0:01:56 what’s going on at a deeper level. In fact, it’s a little bit
0:01:59 confusing or paradoxical. Turns out that there are multiple
0:02:02 populations of neurons in there, some are promoting feeding,
0:02:07 and some are promoting not feeding or not eating. Now, the
0:02:09 other neural component of all this that you need to know
0:02:12 about, actually has to do with your mouth. So there’s an area
0:02:14 of your cortex. So that’s a little bit further up in your
0:02:19 brain, called the insular cortex. And it processes a lot of
0:02:21 different kinds of information, mostly information about what’s
0:02:25 going on inside you so called interoception. The insular
0:02:29 cortex has neurons that get input from your mouth from the
0:02:33 touch receptors in your mouth. An insular cortex has powerful
0:02:36 control over whether or not you are enjoying what you’re eating,
0:02:39 whether or not you want to avoid what you’re eating, whether or
0:02:42 not you’ve had enough or whether or not you want to continue
0:02:45 eating more. And that has to do, believe it or not, with the
0:02:49 touch or sensation of eating. But the key point right now is to
0:02:51 know that you got these two brain areas, the ventromedial
0:02:56 hypothalamus that’s involved in hunger and lack of hunger. And
0:02:58 you have this insular cortex that gets input from your mouth and
0:03:02 cares about chewing and the consistency of foods, and all
0:03:04 sorts of interesting things that are just very tactile. And I
0:03:07 think most people think about the touch receptors on, excuse
0:03:09 me, the taste receptors on the tongue, but we often don’t think
0:03:14 about the touch or tactile essence of food. Now, let’s get
0:03:17 back to the ventromedial hypothalamus. Sometimes it makes
0:03:20 animals or people want to eat more, sometimes less. So what’s
0:03:23 going on there? There’s a classic experiment that was done in
0:03:28 which researchers took two rats and so called parabiost them to
0:03:30 each other. What that meant is that they did a little surgery
0:03:33 and they linked their blood supply so that they were forever
0:03:36 physically linked to one another and could exchange factors in
0:03:39 the blood. But their brains were separate, their mouths were
0:03:42 separate, and they essentially did everything separately,
0:03:43 except that they were linked to one another. So they had to walk
0:03:48 together and go to the same places in order to do it. This
0:03:52 parabiosis experiment revealed something really important. When
0:03:55 they lesioned the ventromedial hypothalamus in one of the rats
0:03:59 that was connected to the other rat, that rat got very, very fat
0:04:04 is just really obese. The other one, however, got very thin. It
0:04:07 actually lost weight. So what does this tell us? This tells us
0:04:10 that there’s something in the blood that’s being exchanged
0:04:13 between the two animals, because it was their blood supply that
0:04:17 was linked. And that tells us that there’s hormone or endocrine
0:04:21 signals that are involved in the desire to eat and hunger and
0:04:24 appetite. And so next, we’re going to talk about what those
0:04:27 endocrine signals are. And then I’m going to immediately point
0:04:31 to some entry points that you can use. And you can use these
0:04:35 even if you’re not parabiosed to anything. And that can allow you
0:04:39 to time your meal frequency and predict when you’re going to be
0:04:43 hungry or not. So let’s talk about the endocrine factors that
0:04:46 regulate feeding hunger and satiety. I’d like to take a quick
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0:06:02 link is David protein.com/huberman. One of the really
0:06:06 exciting things to emerge in the science of feeding and appetite
0:06:10 in the last 20 years is the discovery of another brain area,
0:06:13 not just the ventromedial hypothalamus, but it’s an area
0:06:16 of the brain called the arcuate nucleus. And the arcuate
0:06:21 nucleus has some really fascinating sets of neurons that
0:06:25 release even more incredible molecules and chemicals into the
0:06:29 blood. And these chemicals act as accelerators on feeding and
0:06:33 appetite or breaks. So first of all, there are a set of neurons
0:06:38 in this arcuate nucleus. It’s the pro-opio melanocortin system.
0:06:43 Now the POMC neurons make something called alpha MSH,
0:06:49 melanocyte stimulating hormone alpha melanocyte stimulating
0:06:55 hormone. MSH reduces appetite. And it’s a powerful molecule.
0:06:59 All right, so just put that on the shelf. MSH reduces appetite.
0:07:03 Now there’s another population of neurons in the arcuate nucleus
0:07:08 called the AGRP neurons. The AGRP neurons stimulate eating. The
0:07:13 activity in these AGRP neurons goes way up when animals or
0:07:17 people haven’t eaten for a while. And the activity of MSH, the
0:07:21 release of MSH goes up when we’ve eaten. Next, let’s talk
0:07:25 about a hormone peptide that activates hunger. And this is a
0:07:29 really interesting one, because it relates to when you get
0:07:33 hungry. In addition to the fact that you get hungry at all. And
0:07:39 it’s called ghrelin. It’s spelled G-H-R-E-L-I-N ghrelin is
0:07:45 released actually from the GI tract. And its main role is to
0:07:49 increase your desire to eat. And it does that through a variety
0:07:53 of mechanisms. Part of that is to stimulate some of the brain
0:07:57 areas, the actual neurons that make you want to eat. In
0:08:00 addition, it creates food anticipatory signals within your
0:08:02 nervous system. So you start thinking about the things that
0:08:07 you happen to like to eat at that particular time of day. This
0:08:11 is fascinating. Ghrelin is sort of like a clock, a hormonal
0:08:14 clock that makes you want to eat at particular times. Now the
0:08:19 signal for ghrelin is reduced glucose levels in the blood. If
0:08:23 it drops too low, ghrelin is secreted from your gut. It
0:08:27 activates neurons in your brain at various locations. We all
0:08:30 know about the famous Pavlovian experiments of Pavlog’s dogs,
0:08:32 you know, they start salivating to the bell after the bell was
0:08:34 presented with food, you remove the food and then just the bell
0:08:39 can stimulate the salivation, we become Pavlovian at times. But
0:08:41 rarely has it ever discussed what the neural pathways for that
0:08:45 are. And it turns out that these hormones that are secreted from
0:08:49 the gut can stimulate the neurons to create a sensation and a
0:08:54 desire for certain foods at certain times of day. You’ve done
0:08:59 this experiment. If you are somebody who eats breakfast at
0:09:02 more or less the same time each day, let’s say 8am, your
0:09:06 ghrelin secretion will start to match when you typically eat.
0:09:10 And it’s able to override the low levels of glucose in your
0:09:15 bloodstream, because the ghrelin system also gets input from a
0:09:19 clock in your liver that is linked to the clock in your
0:09:22 hypothalamus in your brain. And what this means is if you eat
0:09:25 at regular meal times, you will start to get hungry a few
0:09:27 minutes before those meals times. If you’ve ever wondered
0:09:31 why your stomach kind of starts to growl, because it’s a
0:09:34 particular time of day, you’re like, Oh, I must want to eat.
0:09:38 Well, that’s ghrelin. So ghrelin is secreted as a kind of food
0:09:42 anticipatory signal to get you motivated to go eat at regular
0:09:46 times. But what that means is that if you suddenly go from
0:09:50 eating on a very regular schedule to skipping a meal, or
0:09:53 pushing your meal timing out or shifting at all, you’re going
0:09:56 to have ghrelin in your system. And that ghrelin is going to
0:09:58 stimulate the desire to eat by acting at the level of your
0:10:02 brain. So ghrelin stimulates the agrp neurons, which makes you
0:10:06 want to eat. Regularity of eating equals regularity of
0:10:09 ghrelin secretion equals regularity of activity of these
0:10:12 agrp neurons, meaning you will be hungry at very regular
0:10:16 intervals. So if MSH inhibits feeding makes us want to eat
0:10:21 less, and ghrelin makes us want to eat more. There’s another
0:10:27 hormone called CCK, cholecystokinin, that is potent in
0:10:34 reducing our levels of hunger. Now CCK is in the GI tract, it’s
0:10:38 released from the GI tract, and its release is governed by two
0:10:41 things. One is a subset of very specialized neurons that
0:10:46 detect what’s in the gut, the specific contents of the gut. And
0:10:50 by certain elements of the mucosa of the mucous lining of the
0:10:55 gut and the gut microbiome. So what’s really interesting is that
0:11:03 CCK is stimulated by fatty acids, amino acids, and particular
0:11:07 amino acids that we’ll talk about, as well as by sugar. So
0:11:11 which fatty acids in the gut stimulate the release of CCK,
0:11:17 omega three fatty acids, and conjugated linoleic acid, CLA,
0:11:21 either from food or from supplements, stimulate the
0:11:24 release of CCK, which then reduces or at least blunts
0:11:28 appetite. The other thing that stimulates CCK that I mentioned
0:11:32 are amino acids. So when we eat, we have the ability to
0:11:35 break down different macronutrients, you know,
0:11:41 carbohydrates, fats, or proteins into sugars and glucose
0:11:44 that then we can convert to ATP and all that stuff from the
0:11:46 Krebs cycle from high school, we’re not going to go into that
0:11:49 today. That’s for a future episode. Amino acids, both can be
0:11:53 used as energy through a process called gluconeogenesis of
0:11:57 converting proteins into energy, or those amino acids can be
0:12:00 broken down and then rebuilt into things like repairing
0:12:03 muscle tissue, as well as other forms of cellular repair,
0:12:05 they’re involved in all sorts of things related to protein
0:12:10 synthesis. What does this mean? If we eat the proper amino
0:12:14 acids at the proper levels, if we ingest omega threes and CLA is
0:12:17 conjugated linoleic acids at the proper levels or get them from
0:12:21 supplements, there is a blunting of appetite. Appetite is kept
0:12:24 clamped and we don’t become hyperphagic, we don’t overeat, we
0:12:29 tend to eat within healthy or normal ranges. So this is very
0:12:33 important, because most people don’t understand that when we’re
0:12:38 eating, we are basically fat foraging and amino acid foraging.
0:12:43 In other words, even if it’s not conscious, we are eating until
0:12:46 we trigger the activation of CCK. Now there are other reasons
0:12:49 why we shut down eating to the volume of food in our gut can be
0:12:53 large, and we can feel very distended. That’s the physical
0:12:59 reason, obviously. But at a subconscious level, the gut is
0:13:03 informing the brain via CCK and other mechanisms when we’ve
0:13:07 ingested enough of what we need. So as you can see feeding is an
0:13:09 interplay between brain and body. And it’s some of the
0:13:12 micronutrients and even the breakdown of particular
0:13:15 nutrients that’s putting the accelerator or the break on the
0:13:19 feeding process. You are essentially trying to eat to
0:13:22 get these nutrients and then a signal can be deployed up to your
0:13:25 brain that you’re not really interested in eating that much
0:13:27 more. I’d like to take a quick break and acknowledge our
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0:14:29 drinkag1.com/huberman to claim that special offer. There’s one
0:14:34 particular aspect of food that can powerfully impact CCK. And I
0:14:38 think most people, I’m guessing 99.9% of people out there are not
0:14:42 aware of this. And it has to do with highly processed foods.
0:14:45 There’s a lot of reasons why one would want to avoid highly
0:14:48 processed foods. In fact, if you’re interested in that topic
0:14:51 and the history of whole foods transitioning to highly
0:14:54 processed foods in this country, I highly recommend you listen to
0:14:58 a YouTube video by Dr. Robert Lustig. He’s University of
0:15:01 California, San Francisco. It gives a beautiful description of
0:15:04 the history of this and why the food industry started packing
0:15:08 in additional sugars and salts and turning foods into commodities
0:15:11 is really fascinating. It has no conspiracy theory. It’s just
0:15:14 all scientific facts. It’s really a wonderful lecture as
0:15:18 millions of views should be very easy to find. There’s another
0:15:21 reason to avoid highly processed foods, however, and that has to
0:15:25 do with what’s called emulsifiers. Now, many of you are
0:15:28 familiar with emulsifiers, even though you don’t know it, when
0:15:33 you put detergent in the laundry, that is in contains
0:15:36 emulsifiers. The goal of that detergent is to bring together
0:15:39 fatty molecules with water molecules and be able to
0:15:42 dissociate them and break them up to get the stains out of
0:15:47 clothes and things of that sort. There are a lot of emulsifiers
0:15:52 put into processed foods. And those emulsifiers allow certain
0:15:54 chemical reactions to occur that extends the shelf life of
0:15:58 those foods. Why are emulsifiers bad? Okay, there are a lot of
0:16:00 reasons why they’re bad. But the reason why they’re bad for the
0:16:03 mechanisms that we’ve been talking about today is that when
0:16:07 you ingest those foods, you’re bringing those emulsifiers into
0:16:12 your gut. And those emulsifiers strip away the mucosal lining of
0:16:16 the gut. And they actually cause the neurons that innervate the
0:16:19 gut that extend those little processes we call axons into the
0:16:24 gut to retract deeper into the gut. And as a consequence, you’re
0:16:28 ingesting a bunch of food. And the signals like cck never get
0:16:31 deployed. The signals that actually shut down hunger are
0:16:33 never actually triggered. And so as a consequence, you want to
0:16:37 eat far more of these highly processed foods. In addition, if
0:16:41 you then go from eating a highly processed food to two non
0:16:45 highly processed foods, you’re not able to measure the amounts
0:16:48 of amino acid sugars and fatty acids in those foods as
0:16:52 accurately you’ve actually done structural damage at a micro
0:16:55 level, but structural level damage, excuse me, to the mucosal
0:16:58 lining of the gut. Now this can all be repaired if you stay away
0:17:01 from highly processed foods for some period of time. But the
0:17:05 negative effects of these emulsifiers are quite real. So to
0:17:09 make it really clean and simple, emulsifiers from highly
0:17:13 processed foods are limiting your gut’s ability to detect what’s
0:17:16 in the foods you eat and therefore to deploy the satiety
0:17:19 signals, the signals that shut down hunger. In addition to that,
0:17:22 there’s a parallel mechanism at play that I talked about in a
0:17:24 previous episode, but I’ll remind you again that you have
0:17:29 neurons in your gut that are sensing sugar and are sending a
0:17:34 subconscious signal up to the brain via the vagus nerve. And
0:17:37 those neurons trigger the release of dopamine, which makes
0:17:39 you crave more of that food. So now you’ve got parallel
0:17:43 signals, making you want to eat more sugar, making you
0:17:46 unaware of how much sugar you’ve eaten, and that are
0:17:49 disrupting the inputs to the nervous system that signal to
0:17:52 the rest of your brain and body that you’ve obtained enough
0:17:56 fatty acids and you’ve obtained enough amino acids. So these
0:17:59 highly processed foods are really terrible. And you know, I’m
0:18:02 not out here to say, you know, never enjoy a processed food of
0:18:05 any kind, I’d be a hypocrite because I do eat processed foods
0:18:08 from time to time, although the ones that I tend to eat, I try
0:18:10 and make of the healthier variety. But eating whole foods has
0:18:14 tremendous value and eating highly processed food has
0:18:18 tremendous negative impact on the gut and on the gut brain
0:18:22 axis. The bottom line is that highly processed foods are just
0:18:24 bad for you. They increase weight gain, they disrupt the
0:18:28 lining of your gut in a way that disrupts things like cck and
0:18:31 proper satiety signals. So there’s just so many reasons why
0:18:35 these highly processed foods are terrible. And they can explain a
0:18:38 lot of the ill health effects that we’ve seen in the last 50
0:18:40 years, not just in the United States, but all over the world,
0:18:45 the enormous increase in diabetes juvenile diabetes. It’s just
0:18:50 remarkable how far down the path of bad we’ve gone. And it’s
0:18:53 clear it’s almost a smoking gun what the cause of this is. If
0:18:55 you’d like to learn more about that please please refer to the
0:19:00 Lustig lecture. He also spells out why non processed foods is
0:19:04 far more economical in terms of just at the level of the
0:19:06 household or individual as well as at the societal level.
0:19:09 Really interesting stuff. I highly recommend you check it out.
0:19:12 So now let’s move on to some other hormones that regulate
0:19:16 hunger and satiety, in particular insulin. Now you’ve
0:19:19 probably heard of insulin before insulin is the thing that’s
0:19:22 lacking in type one diabetics. That’s why they have to inject
0:19:25 insulin whenever they eat. The reason they have to do that is
0:19:27 because when they eat, their foods are broken down into
0:19:31 glucose. And in order to shuttle glucose to the appropriate
0:19:34 tissues in the body, and also to keep glucose levels in check,
0:19:38 you need insulin. So the simplest way to think about
0:19:42 insulin and glucose is that when you eat, that food is broken
0:19:47 down into sugars. That’s true, whether or not it’s fats or
0:19:51 it’s sugars or eventually if it’s proteins, they are oxidized
0:19:55 into fuels, as we say, your blood sugar needs to be kept in a
0:19:59 particular range. hypoglycemic means too low hyperglycemic
0:20:04 means too high. And what they called you glycemic EU glycemic
0:20:11 is the healthy range. Now, what those healthy ranges are. In
0:20:16 general, the healthy range, the euclycemic range is about 70 to
0:20:20 100 nanograms per deciliter. Why is it important that glucose be
0:20:24 kept at a particular level? Once you understand that, keeping
0:20:28 glucose in check starts to have a rationale behind it. And the
0:20:31 ways to do that start to make a lot more sense. So the the
0:20:37 reason is, if glucose levels get too high, because of the way
0:20:41 that our cells in particular neurons interact with glucose,
0:20:45 high levels of glucose can damage neurons, it can actually
0:20:48 kill them, you can start getting what are called peripheral,
0:20:52 excuse me, neuropathies, one of the symptoms of some forms of
0:20:56 diabetes is that people start losing the sensation of touch in
0:20:59 their fingers or their hands or their feet, and they can start
0:21:04 going blind. There’s diabetic retinopathies. So it’s very
0:21:08 important that insulin manage your glucose levels. Now, there’s
0:21:13 also type two diabetes, where there’s insulin secreted from
0:21:17 the pancreas, but people are insulin insensitive, there’s a
0:21:22 disruption in the receptors, and insulin insensitivity isn’t
0:21:25 quite the same as having no insulin at all, but it parallels
0:21:28 some of the same mechanisms. Now type one diabetes is often
0:21:32 picked up because someone has a sudden weight loss, because
0:21:34 they’re not processing blood sugar the same way they were
0:21:38 before type two diabetes is often although not always
0:21:42 associated with being overweight and with obesity. Both of them
0:21:46 are challenging conditions type two diabetes almost always can
0:21:52 be managed by managing one’s weight. And of course, there are
0:21:54 prescription drugs and supplements that can help
0:21:58 manage those we’re going to talk about all of that. But for
0:22:00 most people that don’t have diabetes, the important thing is
0:22:05 to manage glucose to keep it in that euglycemic range. And
0:22:07 there are a number of different ways to do that. Some of them
0:22:12 are behavioral, some of them are diet based, and some of them are
0:22:14 based on supplements or prescription drugs. So let’s
0:22:17 talk about those now. I’d like to take a quick break and
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0:23:45 particular, if you eat carbohydrates, blood glucose
0:23:48 goes up. If you eat fats, blood glucose goes up to a far less
0:23:53 degree. And if you eat proteins, depending on the protein, it
0:23:56 will eventually be broken down for fuel or assembled into
0:23:59 amino acid chains for protein synthesis and repair of other
0:24:04 tissues and bodily functions. But glucose goes up and then is
0:24:09 kept in range. When you are hungry, you secrete a different
0:24:12 hormone and that’s called glucagon. And glucagon’s main
0:24:19 role is to pull stores of energy out of the liver and the
0:24:22 muscles. And once those are depleted, you’ll eventually
0:24:27 tap into body fat. So the two kind of push and pull systems
0:24:29 that we’re going to think about now to keep this simple is that
0:24:34 you have the insulin system managing glucose. And you’ve
0:24:38 got the glucagon system pulling energy out of your liver and
0:24:43 muscles for immediate fuel. And eventually, you’ll pull fuel
0:24:46 out of body fat. If you’ve been active for a very long time,
0:24:49 and all your glycogen stores are depleted or close to
0:24:53 depleted. So what does this all mean? Let’s say you had a meal
0:24:59 and that meal consisted of rice, a carbohydrate, some meat or
0:25:03 fish, let’s say a piece of salmon, and some vegetable, some
0:25:05 fibers, vegetable like asparagus or cabbage or
0:25:10 something like that. If you were to eat all of that at once, you
0:25:12 know, you take a bite of one, a bite of the other, you mix it
0:25:16 up, then you will experience an increase in insulin and increase
0:25:20 in blood glucose. That’s moderately fast. It’s going to
0:25:24 increase pretty quickly. What’s remarkable is that the order
0:25:27 that you consume each macronutrient has a pretty
0:25:32 profound influence on the rate of insulin and glucose
0:25:35 secretion into the blood and how quickly those levels rise. If
0:25:38 you were to eat the fibrous thing first, so a lot of chewing,
0:25:40 but not a big rise in blood glucose, that will actually
0:25:45 blunt the release of glucose until you eat the fish and the
0:25:49 rice. But believe it or not, it will actually blunt the glucose
0:25:52 increase that the rice would cause. Now, I’m not talking
0:25:55 about neurotically eating each macronutrient separately in
0:25:57 sequence. I’m just trying to give you a picture of what’s
0:26:01 happening ordinarily. So what does this all mean? It means
0:26:04 that if you want a steep increase in glucose, you are very,
0:26:07 very hungry, then you should eat the the carbohydrate, laden
0:26:10 food first, or you should eat a bunch of macronutrients
0:26:13 combined. So that would be like the hamburger or the sandwich,
0:26:16 the bread, the whatever’s in that sandwich all together.
0:26:20 Usually that’s protein and, you know, vegetables as well. If
0:26:24 you want to have a kind of more modest increase in glucose, or
0:26:27 you want to blunt the increase in glucose, then have the, at
0:26:32 least some of the fibrous thing first, and then the protein and
0:26:34 then the carbohydrate, you will notice that your blood glucose
0:26:39 will rise more steadily, and that you’ll achieve satiety
0:26:41 earlier in the meal. Basically, what you’re trying to avoid are
0:26:44 steep increases in blood sugar. And the order that you eat
0:26:47 foods has an enormous impact on that. The other thing that has
0:26:52 an enormous impact on how long and shallow or how steep that
0:26:57 curve of glucose is depends on whether or not you recently were
0:27:02 moving are moving or start moving after you eat. So it turns
0:27:06 out that your blood glucose levels can be modulated very, very
0:27:10 powerfully by movement. If you did any kind of intense exercise,
0:27:14 or even just walking or jogging or cycling anything before you
0:27:17 eat, your blood glucose levels will be dampened somewhat. And
0:27:22 even just moving after a meal, even just a calm, easy walk can
0:27:25 really adjust the ways in which blood sugar regulated for the
0:27:28 better. The other thing I’d like to address for a moment is this
0:27:32 notion of stable blood sugar versus labile blood sugar or
0:27:36 unstable blood sugar. Some people just have stable blood sugar.
0:27:40 They can go long periods of time without eating and feel fine.
0:27:44 Other people get really shaky, really jittery. And or when they
0:27:48 do eat, they feel really keyed up. Sometimes they’ll even sweat.
0:27:50 But whether or not your blood sugar is all over the place or
0:27:54 whether or not stable can be impacted by a number of things.
0:27:59 One of those things is exercise. So these days, there’s a lot of
0:28:01 interest in what they call zone two cardio, which is that kind
0:28:04 of steady state cardio where you can just nasal breathe, even at
0:28:08 pretty high output, where you could maybe have a conversation
0:28:13 zone to cardio that lasts anywhere from 30 minutes to an
0:28:17 hour or sometimes more for your endurance athletes can create
0:28:23 positive effects on blood sugar regulation such that you people
0:28:26 can sit down and enjoy whatever it is the hot fudge Sunday or
0:28:29 whatever the high sugar content food is. And blood glucose
0:28:34 management is so good. Your insulin sensitivity is so high,
0:28:37 which is a good thing that you can manage that blood glucose to
0:28:41 the point where it doesn’t really make you shaky, it doesn’t
0:28:46 disrupt you. Basically, doing zone two cardio for 30 to 60
0:28:49 minutes, three to four times a week makes your blood sugar
0:28:52 really stable. And that’s an attractive thing for a variety
0:28:55 of reasons. On the flip side, high intensity interval training
0:28:59 or resistance training, aka weight training, are very good at
0:29:03 stimulating the various molecules that promote repackaging of
0:29:07 glycogen. So sprints, heavy weightlifting, circuit type
0:29:10 weightlifting provided there’s some reasonable degree of
0:29:13 resistance. Those are going to trigger all sorts of mechanisms
0:29:17 that are going to encourage the body to shuttle glucose back
0:29:21 into glycogen convert into glycogen into muscle tissue,
0:29:24 restock the liver, etc. And I should mention that one of the
0:29:28 advantages of high intensity interval training, or weight
0:29:33 lifting of various kinds, is that it also it causes long
0:29:37 standing increases in basal metabolic rate. Now I’d like to
0:29:40 turn to prescription drugs that regulate the hormone systems,
0:29:45 controlling feeding and satiety. There’s a prescription drug
0:29:49 metformin, which was developed as a treatment for diabetes, and
0:29:53 it works potently to reduce blood glucose. It has dramatic
0:30:00 effects in lowering blood glucose. Metformin involves changes
0:30:04 to mitochondrial action in the liver. That’s its main way of
0:30:08 depleting or reducing blood glucose. And it does so through
0:30:13 the so called AMPK pathway. And it increases insulin
0:30:17 sensitivity overall. Metformin is a powerful drug. In fact, I’m
0:30:22 surprised that so many people have sought it out, given that
0:30:25 most of the people that I’m aware of that sought it out are not
0:30:28 diabetic. I do want to mention, because I’m sure some of you out
0:30:30 there are curious about the ketogenic diet, I’m going to do
0:30:35 an entire episode about ketosis and the brain and the body. But
0:30:40 the ketogenic diet has been shown in 22 studies to have a
0:30:42 notable decrease on blood glucose. And that is not
0:30:46 surprising because you’re the essence of the of the ketogenic
0:30:50 diet is that you’re consuming very little or zero of the foods
0:30:55 that promote big spikes in insulin and glucose. If you
0:30:58 consume enough protein, some of that protein can be converted
0:31:01 into glucose, of course, through gluconeogenesis. But the
0:31:06 ketogenic diet has very strong support as for its role in
0:31:10 regulating blood sugar, which is glucose. But the specific
0:31:14 effects of the ketogenic diet and one particular effect that I
0:31:18 will address later, but I’ll mention now, which is the ability
0:31:23 of the ketogenic diet to adjust thyroid hormone levels in ways
0:31:26 that make it such that if you return to eating carbohydrates
0:31:30 after being in ketosis for too long, you don’t manage thyroid
0:31:33 and carbohydrates as well, that has been shown as well. So we’re
0:31:36 going to dive deep into ketosis in a future episode. So for you,
0:31:39 ketoneastas out there, don’t worry. I certainly have nothing
0:31:42 against ketogenic diet. I actually don’t have anything for
0:31:45 or against any particular nutrition plan. I know it works
0:31:48 for me, at least at this stage in my life, and I’ll update it if
0:31:51 I need to, I’m simply trying to get you as much information as I
0:31:55 possibly can so that you can navigate through that landscape in
0:31:59 a way that’s in keeping with your particular goals. I’d like to
0:32:02 take a quick break and thank one of our sponsors, Element.
0:32:05 Element is an electrolyte drink that has everything you need
0:32:08 and nothing you don’t. That means the electrolytes, sodium
0:32:12 magnesium and potassium in the correct ratios, but no sugar. We
0:32:14 should all know that proper hydration is critical for
0:32:17 optimal brain and body function. In fact, even a slight degree
0:32:20 of dehydration can diminish your cognitive and physical
0:32:23 performance to a considerable degree. It’s also important
0:32:25 that you’re not just hydrated, but that you get adequate
0:32:28 amounts of electrolytes in the right ratios. Drinking a packet
0:32:31 of element dissolved in water makes it very easy to ensure
0:32:33 that you’re getting adequate amounts of hydration and
0:32:36 electrolytes. To make sure that I’m getting proper amounts of
0:32:39 both, I dissolve one packet of element in about 16 to 32
0:32:42 ounces of water when I wake up in the morning, and I drink
0:32:45 that basically first thing in the morning. I’ll also drink a
0:32:47 packet of element dissolved in water, drink any kind of physical
0:32:50 exercise that I’m doing, especially on hot days when I’m
0:32:53 sweating a lot and losing water and electrolytes. There are a
0:32:56 bunch of different great tasting flavors of element. I like the
0:32:59 watermelon, I like the raspberry, I like the citrus. Basically, I
0:33:01 like all of them. If you’d like to try Element, you can go to
0:33:05 drinkelement.com/huberman to claim an Element sample pack with
0:33:08 the purchase of any Element drink mix. Again, that’s Drink
0:33:13 Element spelled LMNT. So it’s drinkelement.com/huberman to
0:33:17 claim a free sample pack. So now you understand a lot about
0:33:20 blood sugar and how it’s managed and the ways that you can
0:33:23 manage it better depending on your particular needs. This is
0:33:27 also a good opportunity for us to look back at some of the
0:33:31 medical literature, because it really points to just how far
0:33:34 we’ve come in terms of understanding these important
0:33:38 mechanisms. And it points us in the direction of some actionable
0:33:43 protocols. So diabetes, which is these huge increases in blood
0:33:48 glucose, because there’s no insulin, was known about as
0:33:53 early as 1500 BC, which is just incredible. And the way
0:33:58 physicians then understood that certain people had high blood
0:34:01 glucose without actually knowing what blood glucose was, is
0:34:04 that they would take the urine of particular patients, and they’d
0:34:10 find that ants preferably move toward and consume the urine of
0:34:14 certain patients and not others. And they understood that
0:34:17 there was something in that urine that was correlated with a
0:34:20 sudden weight loss. And some of the other probably very
0:34:24 unfortunate health symptoms that these people were experiencing.
0:34:28 So they knew that there was something in blood and urine. Now
0:34:34 this business of measuring blood sugar from the urine has been
0:34:37 something that lasted way beyond these early stages of, you
0:34:44 know, 1500 BC, turns out that as late as 1674, physicians at
0:34:48 Oxford University were figuring out who had pathologically
0:34:53 high levels of blood glucose by analyzing their urine. And
0:34:56 again, they were measuring the sweetness of their urine. But
0:34:59 and this is medical fact, they would do this by taking urine
0:35:04 samples from different patients and tasting them. And they
0:35:10 developed an intuitive sense of what excessively sweet urine was
0:35:13 relative to the other urines that they had tasted. So for those
0:35:15 of you that are in the medical profession or those of you that
0:35:18 are seeking out the medical profession, do understand this is
0:35:22 not done anymore. And you can also just reflect on how far we’ve
0:35:26 come in terms of the medical profession itself in our ability
0:35:29 to measure things from the blood and measure things from urine
0:35:35 without having to ask ants, which urine is sweeter or ask
0:35:38 oneself which urine is sweeter. So indeed, we are making
0:35:42 progress as a species. Before we close out today, I want to talk
0:35:45 about one more tool that many of you will probably find useful.
0:35:50 I certainly have. I’m a big consumer of caffeine, although I
0:35:53 don’t consume a ton of it. I consume it very consistently. So
0:35:59 I’m big on consuming mate, which is a strong caffeinated tea. And
0:36:03 I generally do that early in the day. Although I do delay about
0:36:05 two hours after I wake up for reasons I’ve talked about in
0:36:08 previous episode to maintain that nice arc of alertness and
0:36:13 focus. Mate also called Yerba mate is an interesting compound
0:36:17 because unlike coffee, it has been shown to increase something
0:36:22 called glucagon like peptide GLP one and increase leptin
0:36:25 levels. Now, we didn’t talk a lot about glucagon today.
0:36:28 Glucagon is really elevated in the fasting state. I mentioned
0:36:32 that it’s sort of the opposite of insulin in kind of rough
0:36:38 terms. That’s one way to think about it. But GLP one or glucagon
0:36:43 like peptide one is increased by ingesting mate and it acts as
0:36:47 a pretty nice appetite suppress. Now, I’m not trying to
0:36:51 suppress my appetite. I like to eat as I mentioned before, but
0:36:56 it works really well to stimulate the brain and to give you a
0:36:59 level of alertness and to do a lot of the things that coffee
0:37:04 does. It also contains electrolytes. So we meaning our
0:37:09 neurons and our brain run on a variety of factors, electrical
0:37:11 activity and chemical transmission, etc. But they
0:37:14 require adequate levels of sodium potassium and magnesium.
0:37:19 If you were to learn the biology or the physiology of the
0:37:22 action potential, the firing of a neuron, something we teach
0:37:24 every first year neuroscience student, and I’d be happy to
0:37:29 teach you if you’re interested, you’ll hear about sodium rushing
0:37:33 into cells and potassium entering and leaving cells in
0:37:36 order to allow neurons to communicate. Electrolytes are
0:37:39 critically important for the function of the nervous system.
0:37:44 And many things that act as diuretics that promote excretion
0:37:49 of water, like caffeine, can also take electrolytes out
0:37:52 along within particular sodium. And sometimes the lightheadedness
0:37:55 or the brain fog that people experience isn’t just because
0:37:57 electrolytes are low, but because they’re kind of out of
0:38:01 balance. So I like mate because it has electrolytes, it has
0:38:05 caffeine, it stimulates the release of this glucagon like
0:38:08 peptide GLP one and it’s been a big help to me in extending that
0:38:12 early morning fasting window out to about noon or so when I eat
0:38:15 my first meal. It also just tastes really good. And the fact
0:38:20 that glucagon like peptide one is enriched or is released more
0:38:25 when you drink mate and the fact that GLP one can regulate blood
0:38:30 sugar in ways that keep your blood sugar in that we called
0:38:35 you got glycemic not too high, not too low mode is one reason why
0:38:40 ingesting mate is attractive to me. So your but mate GLP one can
0:38:44 manage in healthy ways, leptin levels, glucose levels and
0:38:47 glucagon levels in ways that if it serves you that you might
0:38:50 want to try. So once again, we covered an enormous amount of
0:38:56 material focused on how hormones regulate feeding hunger. And
0:39:00 when one feels they don’t need to eat so called satiety that
0:39:04 you’ve had enough. We’ve just focused today mainly on things
0:39:08 like ghrelin on things like melanocyte simulating hormone
0:39:12 incredible, powerful hormone that can suppress appetite on
0:39:16 things like cholecystokinin that comes from the gut and can
0:39:20 suppress appetite on things like food emulsifiers on the fact
0:39:24 that when you’re eating you are amino acid seeking even though
0:39:27 you might not realize it that you are also seeking out
0:39:29 particular fatty acids are tried to give you a number of
0:39:33 actionable tools. Again, always do what’s best for your health
0:39:36 and do that in company with a health care professional. I’m
0:39:38 not a physician. I don’t prescribe anything. I’m a
0:39:42 professor. I profess a lot of things. If you know anyone that’s
0:39:45 interested in this topic or you think that someone could benefit
0:39:48 from it, please suggest the podcast to them as well. And
0:39:50 most of all, thank you for your interest in science.
0:39:53 (upbeat music)
0:39:55 (guitar music)