How to Control Hunger, Eating & Satiety

00:00:00.000 | - Welcome to Huberman Lab Essentials,

00:00:02.320 | where we revisit past episodes

00:00:04.380 | for the most potent and actionable science-based tools

00:00:07.560 | for mental health, physical health, and performance.

00:00:10.340 | I'm Andrew Huberman,

00:00:12.920 | and I'm a professor of neurobiology and ophthalmology

00:00:16.020 | at Stanford School of Medicine.

00:00:18.040 | This podcast is separate

00:00:19.240 | from my teaching and research roles at Stanford.

00:00:21.660 | It is, however, part of my desire and effort

00:00:23.700 | to bring zero cost to consumer information

00:00:25.760 | about science and science-related tools

00:00:28.040 | to the general public.

00:00:29.360 | Today, we're going to talk about how hormones

00:00:31.240 | impact feeding and hunger, as well as satiety,

00:00:35.040 | the feeling that you don't want to eat

00:00:36.560 | or that you've eaten enough.

00:00:38.720 | Now, it's important to understand

00:00:40.000 | that hormones don't work alone in this context.

00:00:42.660 | Today, I'm going to describe some hormones

00:00:44.480 | that have powerful effects

00:00:46.080 | on whether or not you want to eat more or less

00:00:48.380 | or stop eating altogether.

00:00:50.720 | But they don't do that on their own.

00:00:52.760 | They do that in cooperation with the nervous system.

00:00:55.460 | The first thing that you need to know

00:00:57.000 | about the nervous system side,

00:00:58.680 | the neural control over feeding and hunger,

00:01:01.060 | is that there's an area of your brain

00:01:02.520 | called the hypothalamus.

00:01:04.000 | Now, the hypothalamus contains lots of different kinds

00:01:06.720 | of neurons doing lots of different kinds of things.

00:01:09.000 | There's a particular area of the hypothalamus

00:01:11.440 | called the ventromedial hypothalamus.

00:01:14.360 | And it's one that researchers have been interested

00:01:16.800 | for a long time now

00:01:18.520 | in terms of its relationship to hunger and feeding.

00:01:21.200 | And the reason is it creates these paradoxical effects.

00:01:25.800 | What do I mean by that?

00:01:26.720 | What they found was that sometimes lesioning

00:01:29.320 | or disrupting the neurons in the ventromedial hypothalamus

00:01:32.200 | would make animals or people hyperphagic.

00:01:34.540 | They would want to eat like crazy.

00:01:36.840 | And other lesions in other individuals or animals

00:01:41.040 | would make them anorexic.

00:01:42.320 | It would make them not want to eat at all.

00:01:44.120 | It would make food aversive.

00:01:45.760 | So that means that the ventromedial hypothalamus

00:01:48.240 | is definitely an interesting control station

00:01:50.300 | for hunger and feeding and satiety,

00:01:52.200 | but it doesn't really tell you what's going on

00:01:54.240 | at a deeper level.

00:01:55.320 | In fact, it's a little bit confusing

00:01:56.640 | or paradoxical.

00:01:58.160 | It turns out that there are multiple populations

00:02:00.100 | of neurons in there.

00:02:00.940 | Some are promoting feeding

00:02:02.520 | and some are promoting not feeding or not eating.

00:02:06.320 | Now, the other neural component of all this

00:02:08.800 | that you need to know about

00:02:10.400 | actually has to do with your mouth.

00:02:12.240 | So there's an area of your cortex.

00:02:13.560 | So that's a little bit further up in your brain

00:02:16.160 | called the insular cortex.

00:02:17.840 | And it processes a lot of different kinds of information,

00:02:20.240 | mostly information about what's going on inside you,

00:02:22.660 | so-called interoception.

00:02:24.680 | The insular cortex has neurons

00:02:27.040 | that get input from your mouth,

00:02:29.540 | from the touch receptors in your mouth.

00:02:31.840 | An insular cortex has powerful control

00:02:34.120 | over whether or not you are enjoying what you're eating,

00:02:36.780 | whether or not you want to avoid what you're eating,

00:02:39.120 | whether or not you've had enough

00:02:40.480 | or whether or not you want to continue eating more.

00:02:43.280 | And that has to do, believe it or not,

00:02:45.140 | with the touch or sensation of eating.

00:02:47.760 | But the key point right now

00:02:49.080 | is to know that you've got these two brain areas,

00:02:50.480 | the ventromedial hypothalamus,

00:02:52.120 | that's involved in hunger and lack of hunger.

00:02:55.600 | And you have this insular cortex

00:02:57.320 | that gets input from your mouth

00:02:58.680 | and cares about chewing and the consistency of foods

00:03:01.920 | and all sorts of interesting things

00:03:03.320 | that are just very tactile.

00:03:04.760 | And I think most people think about the touch receptors on,

00:03:06.840 | excuse me, the taste receptors on the tongue,

00:03:08.960 | but we often don't think about

00:03:10.560 | the touch or tactile essence of food.

00:03:13.880 | Now, let's get back to the ventromedial hypothalamus.

00:03:16.600 | Sometimes it makes animals or people want to eat more,

00:03:19.360 | sometimes less.

00:03:20.200 | So what's going on there?

00:03:21.400 | There's a classic experiment that was done

00:03:23.700 | in which researchers took two rats

00:03:26.260 | and so-called parabiose to them to each other.

00:03:28.820 | What that meant is that they did a little surgery

00:03:30.640 | and they linked their blood supply

00:03:32.440 | so that they were forever physically linked to one another

00:03:35.200 | and could exchange factors in the blood,

00:03:37.680 | but their brains were separate, their mouths were separate,

00:03:39.740 | and they essentially did everything separately

00:03:42.020 | except that they were linked to one another.

00:03:43.340 | So they had to walk together

00:03:44.180 | and go to the same places in order to do it.

00:03:46.380 | This parabiosis experiment

00:03:49.740 | revealed something really important.

00:03:51.780 | When they lesioned the ventromedial hypothalamus

00:03:53.920 | in one of the rats that was connected to the other rat,

00:03:57.240 | that rat got very, very fat.

00:03:59.980 | It's just really obese.

00:04:01.660 | The other one, however, got very thin.

00:04:04.700 | It actually lost weight.

00:04:06.260 | So what does this tell us?

00:04:07.260 | This tells us that there's something in the blood

00:04:09.740 | that's being exchanged between the two animals

00:04:12.260 | because it was their blood supply that was linked.

00:04:14.900 | And that tells us that there's hormone or endocrine signals

00:04:18.620 | that are involved in the desire to eat

00:04:20.820 | and hunger and appetite.

00:04:22.540 | And so next, we're going to talk about

00:04:23.780 | what those endocrine signals are.

00:04:25.820 | And then I'm going to immediately point

00:04:27.760 | to some entry points that you can use,

00:04:29.860 | and you can use these

00:04:31.400 | even if you're not parabiosed to anything,

00:04:33.980 | and that can allow you to time your meal frequency

00:04:38.020 | and predict when you're going to be hungry or not.

00:04:40.860 | So let's talk about the endocrine factors

00:04:43.020 | that regulate feeding, hunger, and satiety.

00:04:45.580 | One of the really exciting things to emerge

00:04:47.900 | in the science of feeding and appetite in the last 20 years

00:04:52.340 | is the discovery of another brain area,

00:04:54.340 | not just the ventromedial hypothalamus,

00:04:56.300 | but it's an area of the brain called the arcuate nucleus.

00:04:59.540 | And the arcuate nucleus

00:05:01.620 | has some really fascinating sets of neurons

00:05:04.580 | that release even more incredible molecules

00:05:08.100 | and chemicals into the blood.

00:05:10.160 | And these chemicals act as accelerators

00:05:12.400 | on feeding and appetite or breaks.

00:05:14.860 | So first of all, there are a set of neurons

00:05:16.960 | in this arcuate nucleus.

00:05:18.300 | It's the pro-opio-melanocortin system.

00:05:21.980 | Now, the POMC neurons make something called alpha-MSH,

00:05:26.980 | melanocyte-stimulating hormone,

00:05:30.820 | alpha-melanocyte-stimulating hormone.

00:05:33.700 | MSH reduces appetite, and it's a powerful molecule.

00:05:38.700 | All right, so just put that on the shelf.

00:05:40.740 | MSH reduces appetite.

00:05:43.240 | Now, there's another population of neurons

00:05:45.180 | in the arcuate nucleus called the AGRP neurons.

00:05:48.160 | The AGRP neurons stimulate eating.

00:05:51.880 | The activity in these AGRP neurons goes way up

00:05:55.440 | when animals or people haven't eaten for a while.

00:05:58.360 | And the activity of MSH, the release of MSH,

00:06:02.380 | goes up when we've eaten.

00:06:04.280 | Next, let's talk about a hormone peptide

00:06:06.520 | that activates hunger.

00:06:08.600 | And this is a really interesting one

00:06:10.740 | because it relates to when you get hungry

00:06:13.660 | in addition to the fact that you get hungry at all.

00:06:16.560 | And it's called ghrelin.

00:06:17.840 | It's spelled G-H-R-E-L-I-N.

00:06:22.360 | Ghrelin is released actually from the GI tract.

00:06:26.360 | And its main role is to increase your desire to eat.

00:06:31.360 | And it does that through a variety of mechanisms.

00:06:34.760 | Part of that is to stimulate some of the brain areas,

00:06:37.580 | the actual neurons that make you want to eat.

00:06:40.800 | In addition, it creates food anticipatory signals

00:06:43.780 | within your nervous system.

00:06:44.740 | So you start thinking about the things

00:06:46.220 | that you happen to like to eat

00:06:48.140 | at that particular time of day.

00:06:50.540 | This is fascinating.

00:06:51.580 | Ghrelin is sort of like a clock, a hormonal clock,

00:06:55.800 | that makes you want to eat at particular times.

00:06:58.140 | Now, the signal for ghrelin

00:06:59.500 | is reduced glucose levels in the blood.

00:07:02.480 | If it drops too low, ghrelin is secreted from your gut.

00:07:06.740 | It activates neurons in your brain at various locations.

00:07:10.260 | We all know about the famous Pavlovian experiments

00:07:13.160 | of Pavlov's dogs.

00:07:14.120 | You know, they start salivating to the bell

00:07:15.620 | after the bell was presented with food.

00:07:16.880 | You remove the food

00:07:17.720 | and then just the bell can stimulate the salivation.

00:07:20.260 | We become Pavlovian at times.

00:07:22.080 | But rarely is it ever discussed

00:07:23.940 | what the neural pathways for that are.

00:07:26.080 | And it turns out that these hormones

00:07:27.880 | that are secreted from the gut

00:07:29.360 | can stimulate the neurons to create a sensation

00:07:32.760 | and a desire for certain foods at certain times of day.

00:07:35.980 | You've done this experiment.

00:07:39.180 | If you are somebody who eats breakfast

00:07:42.440 | at more or less the same time each day,

00:07:44.480 | let's say 8 a.m., your ghrelin secretion

00:07:47.360 | will start to match when you typically eat.

00:07:50.720 | And it's able to override the low levels of glucose

00:07:53.560 | in your bloodstream because the ghrelin system

00:07:56.520 | also gets input from a clock in your liver

00:08:01.400 | that is linked to the clock

00:08:03.080 | in your hypothalamus in your brain.

00:08:04.960 | And what this means is if you eat at regular mealtimes,

00:08:07.400 | you will start to get hungry a few minutes

00:08:08.960 | before those mealtimes.

00:08:10.040 | If you've ever wondered

00:08:10.920 | why your stomach kind of starts to growl

00:08:13.900 | because it's a particular time of day,

00:08:16.000 | you're like, "Oh, I must want to eat."

00:08:17.620 | Well, that's ghrelin.

00:08:19.240 | So ghrelin is secreted as a kind of food anticipatory signal

00:08:23.720 | to get you motivated to go eat at regular times.

00:08:26.880 | But what that means is that if you suddenly go from eating

00:08:30.680 | on a very regular schedule to skipping a meal

00:08:33.280 | or pushing your meal timing out or shifting at all,

00:08:36.900 | you're going to have ghrelin in your system.

00:08:38.400 | And that ghrelin is going to stimulate the desire to eat

00:08:40.980 | by acting at the level of your brain.

00:08:42.780 | So ghrelin stimulates the AGRP neurons,

00:08:45.400 | which makes you want to eat.

00:08:47.160 | Regularity of eating equals regularity of ghrelin secretion

00:08:50.620 | equals regularity of activity of these AGRP neurons,

00:08:53.680 | meaning you will be hungry at very regular intervals.

00:08:56.520 | So if MSH inhibits feeding, makes us want to eat less,

00:09:00.760 | and ghrelin makes us want to eat more,

00:09:04.440 | there's another hormone called CCK, cholecystokinin,

00:09:08.980 | that is potent in reducing our levels of hunger.

00:09:13.720 | Now, CCK is in the GI tract.

00:09:17.380 | It's released from the GI tract.

00:09:19.220 | And its release is governed by two things.

00:09:21.980 | One is a subset of very specialized neurons

00:09:25.260 | that detect what's in the gut,

00:09:26.960 | the specific contents of the gut.

00:09:29.580 | And by certain elements of the mucosa,

00:09:32.860 | the mucous lining of the gut and the gut microbiome.

00:09:36.540 | So what's really interesting is that CCK

00:09:40.580 | is stimulated by fatty acids, amino acids,

00:09:45.580 | and particular amino acids that we'll talk about,

00:09:48.980 | as well as by sugar.

00:09:50.900 | So which fatty acids in the gut

00:09:53.500 | stimulate the release of CCK?

00:09:55.700 | Omega-3 fatty acids and conjugated linoleic acid, CLA,

00:10:01.300 | either from food or from supplements,

00:10:03.740 | stimulate the release of CCK,

00:10:05.860 | which then reduces or at least blunts appetite.

00:10:09.260 | The other thing that stimulates CCK that I mentioned

00:10:12.060 | are amino acids.

00:10:13.540 | So when we eat,

00:10:14.820 | we have the ability to break down different macronutrients,

00:10:19.220 | you know, carbohydrates, fats, or proteins

00:10:23.060 | into sugars and glucose that then we can convert to ATP

00:10:26.740 | and all that stuff from the Krebs cycle from high school.

00:10:28.780 | We're not going to go into that today.

00:10:29.860 | That's for a future episode.

00:10:31.140 | Amino acids both can be used as energy

00:10:34.780 | through a process called gluconeogenesis

00:10:37.220 | of converting proteins into energy,

00:10:39.420 | or those amino acids can be broken down

00:10:41.900 | and then rebuilt into things like repairing muscle tissue,

00:10:44.860 | as well as other forms of cellular repair.

00:10:47.120 | They're involved in all sorts of things

00:10:48.180 | related to protein synthesis.

00:10:50.340 | What does this mean?

00:10:51.940 | If we eat the proper amino acids at the proper levels,

00:10:55.780 | if we ingest omega-3s and CLAs,

00:10:58.060 | conjugated linoleic acids, at the proper levels,

00:11:00.340 | or get them from supplements,

00:11:02.220 | there's a blunting of appetite.

00:11:04.100 | Appetite is kept clamped and we don't become hyperphagic.

00:11:07.180 | We don't overeat.

00:11:08.260 | We tend to eat within healthy or normal ranges.

00:11:11.280 | So this is very important

00:11:13.340 | because most people don't understand that when we're eating,

00:11:18.220 | we are basically fat foraging and amino acid foraging.

00:11:23.180 | In other words, even if it's not conscious,

00:11:26.080 | we are eating until we trigger the activation of CCK.

00:11:29.340 | Now, there are other reasons why we shut down eating too.

00:11:31.420 | The volume of food in our gut can be large

00:11:34.060 | and we can feel very distended.

00:11:35.980 | That's the physical reason, obviously.

00:11:38.960 | But at a subconscious level,

00:11:42.540 | the gut is informing the brain via CCK and other mechanisms

00:11:46.640 | when we've ingested enough of what we need.

00:11:49.020 | So as you can see,

00:11:49.880 | feeding is an interplay between brain and body,

00:11:52.540 | and it's some of the micronutrients

00:11:54.220 | and even the breakdown of particular nutrients

00:11:56.280 | that's putting the accelerator

00:11:58.220 | or the brake on the feeding process.

00:12:00.180 | You are essentially trying to eat to get these nutrients,

00:12:03.900 | and then a signal can be deployed up to your brain

00:12:06.220 | that you're not really interested in eating that much more.

00:12:09.320 | There's one particular aspect of food

00:12:12.220 | that can powerfully impact CCK,

00:12:14.380 | and I think most people,

00:12:15.960 | I'm guessing 99.9% of people out there

00:12:18.100 | are not aware of this.

00:12:19.940 | And it has to do with highly processed foods.

00:12:22.580 | There's a lot of reasons why one would want to avoid

00:12:24.740 | highly processed foods.

00:12:26.600 | In fact, if you're interested in that topic

00:12:28.200 | and the history of whole foods

00:12:30.480 | transitioning to highly processed foods in this country,

00:12:32.540 | I highly recommend you listen to a YouTube video

00:12:35.400 | by Dr. Robert Lustig.

00:12:37.080 | He's at University of California, San Francisco.

00:12:39.160 | It gives a beautiful description of the history of this

00:12:42.320 | and why the food industry started packing in

00:12:44.920 | additional sugars and salts

00:12:46.560 | and turning foods into commodities.

00:12:48.480 | It's really fascinating.

00:12:50.200 | It has no conspiracy theory.

00:12:51.560 | It's just all scientific facts.

00:12:53.320 | It's really a wonderful lecture.

00:12:54.680 | It has millions of views, should be very easy to find.

00:12:57.400 | There's another reason to avoid

00:12:59.160 | highly processed foods, however.

00:13:01.240 | And that has to do with what's called emulsifiers.

00:13:05.040 | Now, many of you are familiar with emulsifiers,

00:13:06.960 | even though you don't know it.

00:13:08.240 | When you put detergent in the laundry,

00:13:11.200 | that contains emulsifiers.

00:13:13.840 | The goal of that detergent is to bring together

00:13:16.640 | fatty molecules with water molecules

00:13:19.240 | and be able to dissociate them and break them up

00:13:21.440 | to get the stains out of clothes and things of that sort.

00:13:24.280 | There are a lot of emulsifiers put into processed foods.

00:13:29.560 | And those emulsifiers allow certain chemical reactions

00:13:32.760 | to occur that extends the shelf life of those foods.

00:13:35.240 | Why are emulsifiers bad?

00:13:37.120 | Okay, there are a lot of reasons why they're bad,

00:13:38.680 | but the reason why they're bad for the mechanisms

00:13:41.000 | that we've been talking about today

00:13:42.660 | is that when you ingest those foods,

00:13:45.040 | you're bringing those emulsifiers into your gut.

00:13:47.720 | And those emulsifiers strip away

00:13:50.760 | the mucosal lining of the gut.

00:13:52.880 | And they actually cause the neurons that innervate the gut,

00:13:56.200 | that extend those little processes we call axons

00:13:58.560 | into the gut to retract deeper into the gut.

00:14:02.280 | And as a consequence, you're ingesting a bunch of food

00:14:05.440 | and the signals like CCK never get deployed.

00:14:08.560 | The signals that actually shut down hunger

00:14:10.880 | are never actually triggered.

00:14:12.300 | And so as a consequence, you want to eat far more

00:14:14.620 | of these highly processed foods.

00:14:16.360 | In addition, if you then go from eating

00:14:18.720 | a highly processed food to non-highly processed foods,

00:14:22.080 | you're not able to measure the amounts of amino acids,

00:14:25.880 | sugars, and fatty acids in those foods as accurately.

00:14:29.120 | You've actually done structural damage at a micro level,

00:14:32.440 | but structural level damage, excuse me,

00:14:34.840 | to the mucosal lining of the gut.

00:14:36.480 | Now this can all be repaired if you stay away

00:14:38.520 | from highly processed foods for some period of time.

00:14:40.920 | But the negative effects of these emulsifiers

00:14:43.160 | are quite real.

00:14:44.400 | So to make it really clean and simple,

00:14:47.040 | emulsifiers from highly processed foods

00:14:50.360 | are limiting your gut's ability to detect

00:14:52.920 | what's in the foods you eat,

00:14:54.100 | and therefore to deploy the satiety signals,

00:14:56.480 | the signals that shut down hunger.

00:14:58.360 | In addition to that, there's a parallel mechanism at play

00:15:01.360 | that I talked about in a previous episode,

00:15:03.200 | but I'll remind you again that you have neurons in your gut

00:15:06.060 | that are sensing sugar and are sending a subconscious signal

00:15:10.640 | up to the brain via the vagus nerve.

00:15:14.040 | And those neurons trigger the release of dopamine,

00:15:16.960 | which makes you crave more of that food.

00:15:18.780 | So now you've got parallel signals

00:15:21.000 | making you want to eat more sugar,

00:15:22.920 | making you unaware of how much sugar you've eaten,

00:15:25.080 | and that are disrupting the inputs to the nervous system

00:15:29.240 | that signal to the rest of your brain and body

00:15:31.040 | that you've obtained enough fatty acids

00:15:33.080 | and you've obtained enough amino acids.

00:15:35.600 | So these highly processed foods are really terrible.

00:15:38.680 | And I'm not out here to say,

00:15:40.800 | never enjoy a processed food of any kind.

00:15:43.200 | I'd be a hypocrite 'cause I do eat processed foods

00:15:45.500 | from time to time.

00:15:46.340 | Although the ones that I tend to eat,

00:15:47.800 | I try and make of the healthier variety,

00:15:49.440 | but eating whole foods has tremendous value

00:15:52.520 | and eating highly processed food

00:15:54.360 | has tremendous negative impact on the gut

00:15:57.520 | and on the gut brain axis.

00:15:59.320 | The bottom line is that highly processed foods

00:16:01.800 | are just bad for you.

00:16:02.680 | They increase weight gain.

00:16:04.040 | They disrupt the lining of your gut

00:16:05.800 | in a way that disrupts things like CCK

00:16:08.120 | and proper satiety signals.

00:16:09.700 | So there's just so many reasons

00:16:11.120 | why these highly processed foods are terrible.

00:16:14.140 | And they can explain a lot of the ill health effects

00:16:16.400 | that we've seen in the last 50 years,

00:16:18.440 | not just in the United States, but all over the world.

00:16:20.360 | The enormous increase in diabetes, juvenile diabetes.

00:16:23.720 | It's just remarkable how far down the path of bad we've gone

00:16:29.680 | and it's clear, it's almost a smoking gun

00:16:31.980 | what the cause of this is.

00:16:33.140 | If you'd like to learn more about that,

00:16:34.920 | please refer to the Lustig lecture.

00:16:36.760 | He also spells out why non-processed foods

00:16:40.240 | is far more economical

00:16:41.880 | in terms of just at the level of the household

00:16:44.440 | or individual, as well as at the societal level.

00:16:47.000 | Really interesting stuff.

00:16:48.000 | I highly recommend you check it out.

00:16:49.400 | So now let's move on to some other hormones

00:16:51.320 | that regulate hunger and satiety.

00:16:53.900 | In particular, insulin.

00:16:56.080 | Now you've probably heard of insulin before.

00:16:58.040 | Insulin is the thing that's lacking in type one diabetics.

00:17:01.420 | That's why they have to inject insulin whenever they eat.

00:17:03.600 | The reason they have to do that

00:17:04.880 | is because when they eat,

00:17:06.200 | their foods are broken down into glucose.

00:17:08.840 | And in order to shuttle glucose

00:17:10.460 | to the appropriate tissues in the body

00:17:12.520 | and also to keep glucose levels in check, you need insulin.

00:17:16.260 | So the simplest way to think about insulin and glucose

00:17:19.800 | is that when you eat, that food is broken down into sugars.

00:17:24.040 | That's true whether or not it's fats or it's sugars

00:17:28.240 | or eventually if it's proteins,

00:17:30.760 | they're oxidized into fuels as we say.

00:17:33.440 | Your blood sugar needs to be kept in a particular range.

00:17:36.320 | Hypoglycemic means too low.

00:17:38.160 | Hyperglycemic means too high.

00:17:40.480 | And what they called euglycemic, E-U glycemic

00:17:45.480 | is the healthy range.

00:17:47.800 | Now, what those healthy ranges are,

00:17:50.160 | in general, the healthy range, the euglycemic range

00:17:54.080 | is about 70 to 100 nanograms per deciliter.

00:17:58.360 | Why is it important that glucose

00:18:00.080 | be kept at a particular level?

00:18:01.640 | Once you understand that,

00:18:04.100 | keeping glucose in check starts to have a rationale

00:18:07.020 | behind it and the ways to do that

00:18:09.420 | start to make a lot more sense.

00:18:10.940 | So the reason is if glucose levels get too high

00:18:15.940 | because of the way that our cells in particular neurons

00:18:19.540 | interact with glucose,

00:18:21.280 | high levels of glucose can damage neurons.

00:18:25.260 | It can actually kill them.

00:18:26.140 | You can start getting what are called peripheral,

00:18:28.500 | excuse me, neuropathies.

00:18:30.260 | One of the symptoms of some forms of diabetes

00:18:32.700 | is that people start losing the sensation of touch

00:18:36.220 | in their fingers or their hands or their feet,

00:18:38.700 | and they can start going blind.

00:18:40.180 | There's diabetic retinopathies.

00:18:43.260 | So it's very important

00:18:45.180 | that insulin manage your glucose levels.

00:18:48.220 | Now, there's also type two diabetes

00:18:50.300 | where there's insulin secreted from the pancreas,

00:18:54.520 | but people are insulin insensitive.

00:18:57.120 | There's a disruption in the receptors

00:18:59.300 | and insulin insensitivity isn't quite the same

00:19:02.700 | as having no insulin at all,

00:19:04.380 | but it parallels some of the same mechanisms.

00:19:06.540 | Now, type one diabetes is often picked up

00:19:08.660 | because someone has a sudden weight loss

00:19:12.120 | because they're not processing blood sugar

00:19:13.980 | the same way they were before.

00:19:15.220 | Type two diabetes is often, although not always,

00:19:18.140 | associated with being overweight and with obesity.

00:19:21.580 | Both of them are challenging conditions.

00:19:24.420 | Type two diabetes almost always can be managed

00:19:27.060 | by managing one's weight.

00:19:29.200 | And of course, there are prescription drugs

00:19:33.660 | and supplements that can help manage those.

00:19:35.460 | We're going to talk about all of that.

00:19:37.240 | But for most people that don't have diabetes,

00:19:39.820 | the important thing is to manage glucose,

00:19:41.700 | to keep it in that euglycemic range.

00:19:44.820 | And there are a number of different ways to do that.

00:19:47.060 | Some of them are behavioral, some of them are diet-based,

00:19:50.500 | and some of them are based on supplements

00:19:53.380 | or prescription drugs.

00:19:54.300 | So let's talk about those now.

00:19:55.800 | So if you eat, and in particular, if you eat carbohydrates,

00:19:59.580 | blood glucose goes up.

00:20:00.980 | If you eat fats, blood glucose goes up to a far less degree.

00:20:04.380 | And if you eat proteins, depending on the protein,

00:20:07.580 | it'll eventually be broken down for fuel

00:20:09.760 | or assembled into amino acid chains for protein synthesis

00:20:13.060 | and repair of other tissues and bodily functions.

00:20:16.260 | But glucose goes up and then is kept in range.

00:20:20.940 | When you are hungry, you secrete a different hormone,

00:20:24.340 | and that's called glucagon.

00:20:26.080 | And glucagon's main role is to pull stores of energy

00:20:31.080 | out of the liver and the muscles.

00:20:34.480 | And once those are depleted,

00:20:36.480 | you'll eventually tap into body fat.

00:20:38.640 | So the two kind of push and pull systems

00:20:41.860 | that we're going to think about now to keep this simple

00:20:44.040 | is that you have the insulin system managing glucose,

00:20:47.880 | and you've got the glucagon system pulling energy

00:20:51.040 | out of your liver and muscles for immediate fuel.

00:20:54.720 | And eventually you'll pull fuel out of body fat

00:20:58.980 | if you've been active for a very long time

00:21:00.740 | and all your glycogen stores are depleted

00:21:03.000 | or close to depleted.

00:21:04.880 | So what does this all mean?

00:21:06.520 | Let's say you had a meal and that meal consisted of rice,

00:21:10.760 | a carbohydrate, some meat or fish,

00:21:14.520 | let's say a piece of salmon, and some vegetable,

00:21:17.420 | some fibrous vegetable like asparagus or cabbage

00:21:19.640 | or something like that.

00:21:20.840 | If you were to eat all of that at once,

00:21:24.520 | you take a bite of one, a bite of the other,

00:21:26.320 | you mix it up, then you will experience an increase

00:21:29.480 | in insulin and increase in blood glucose

00:21:32.000 | that's moderately fast.

00:21:34.960 | It's going to increase pretty quickly.

00:21:37.320 | What's remarkable is that the order

00:21:38.880 | that you consume each macronutrient

00:21:41.280 | has a pretty profound influence on the rate of insulin

00:21:45.460 | and glucose secretion into the blood

00:21:48.080 | and how quickly those levels rise.

00:21:49.820 | If you were to eat the fibrous thing first,

00:21:51.800 | so a lot of chewing, but not a big rise in blood glucose,

00:21:54.400 | that will actually blunt the release of glucose

00:21:58.360 | until you eat the fish and the rice.

00:22:01.000 | But believe it or not,

00:22:02.040 | it will actually blunt the glucose increase

00:22:04.960 | that the rice would cause.

00:22:06.680 | Now, I'm not talking about neurotically

00:22:08.200 | eating each macronutrient separately in sequence.

00:22:10.380 | I'm just trying to give you a picture

00:22:11.600 | of what's happening ordinarily.

00:22:13.660 | So what does this all mean?

00:22:15.440 | It means that if you want a steep increase in glucose,

00:22:18.560 | you are very, very hungry,

00:22:19.680 | then you should eat the carbohydrate-laden food first,

00:22:23.240 | or you should eat a bunch of macronutrients combined.

00:22:25.840 | So that would be like the hamburger or the sandwich,

00:22:27.840 | the bread, whatever's in that sandwich all together.

00:22:31.640 | Usually that's protein and vegetables as well.

00:22:35.240 | If you want to have a kind of more modest

00:22:37.820 | increase in glucose,

00:22:38.800 | or you want to blunt the increase in glucose,

00:22:40.720 | then have at least some of the fibrous thing first,

00:22:44.980 | and then the protein, and then the carbohydrate.

00:22:47.680 | You will notice that your blood glucose

00:22:49.280 | will rise more steadily,

00:22:52.100 | and that you'll achieve satiety earlier in the meal.

00:22:55.080 | Basically what you're trying to avoid

00:22:56.280 | are steep increases in blood sugar.

00:22:57.760 | And the order that you eat foods

00:22:59.120 | has an enormous impact on that.

00:23:01.300 | The other thing that has an enormous impact

00:23:02.960 | on how long and shallow or how steep

00:23:06.520 | that curve of glucose is,

00:23:09.600 | depends on whether or not you recently were moving,

00:23:12.920 | are moving, or start moving after you eat.

00:23:15.700 | So it turns out that your blood glucose levels

00:23:19.040 | can be modulated very, very powerfully by movement.

00:23:22.500 | If you did any kind of intense exercise,

00:23:25.160 | or even just walking, or jogging, or cycling,

00:23:28.280 | anything before you eat,

00:23:29.300 | your blood glucose levels will be dampened somewhat.

00:23:31.620 | And even just moving after a meal,

00:23:33.900 | even just a calm, easy walk,

00:23:36.400 | can really adjust the ways

00:23:37.800 | in which blood sugar regulated for the better.

00:23:40.400 | The other thing I'd like to address for a moment

00:23:42.620 | is this notion of stable blood sugar

00:23:45.280 | versus labile blood sugar, or unstable blood sugar.

00:23:48.760 | Some people just have stable blood sugar.

00:23:51.640 | They can go long periods of time

00:23:53.240 | without eating and feel fine.

00:23:54.680 | Other people get really shaky, really jittery,

00:23:57.560 | and/or when they do eat, they feel really keyed up.

00:24:01.240 | Sometimes they'll even sweat.

00:24:02.860 | But whether or not your blood sugar is all over the place,

00:24:05.220 | or whether or not it's stable,

00:24:07.120 | can be impacted by a number of things.

00:24:09.820 | One of those things is exercise.

00:24:11.960 | So these days, there's a lot of interest

00:24:14.020 | in what they call zone two cardio,

00:24:15.460 | which is that kind of steady state cardio

00:24:17.180 | where you can just nasal breathe,

00:24:18.680 | even at pretty high output,

00:24:20.660 | where you could maybe have a conversation.

00:24:22.820 | Zone two cardio that lasts anywhere from 30 minutes

00:24:27.420 | to an hour, or sometimes more for you endurance athletes,

00:24:30.380 | can create positive effects on blood sugar regulation

00:24:34.460 | such that you, people can sit down

00:24:38.300 | and enjoy whatever it is, the hot fudge sundae,

00:24:40.780 | or whatever the high sugar content food is.

00:24:43.060 | And blood glucose management is so good,

00:24:46.020 | your insulin sensitivity is so high, which is a good thing,

00:24:49.720 | that you can manage that blood glucose

00:24:52.060 | to the point where it doesn't really make you shaky,

00:24:55.100 | it doesn't disrupt you.

00:24:56.900 | Basically, doing zone two cardio for 30 to 60 minutes,

00:25:01.420 | three to four times a week,

00:25:02.580 | makes your blood sugar really stable.

00:25:04.700 | And that's an attractive thing for a variety of reasons.

00:25:07.440 | On the flip side, high intensity interval training,

00:25:10.500 | or resistance training, aka weight training,

00:25:13.020 | are very good at stimulating the various molecules

00:25:16.380 | that promote repackaging of glycogen.

00:25:18.900 | So sprints, heavy weight lifting,

00:25:21.480 | circuit type weight lifting,

00:25:22.740 | provided there's some reasonable degree of resistance,

00:25:25.500 | those are going to trigger all sorts of mechanisms

00:25:27.900 | that are going to encourage the body

00:25:30.620 | to shuttle glucose back into glycogen,

00:25:33.880 | convert into glycogen into muscle tissue,

00:25:35.580 | restock the liver, et cetera.

00:25:37.260 | And I should mention that one of the advantages

00:25:39.200 | of high intensity interval training

00:25:41.940 | or weightlifting of various kinds

00:25:45.460 | is that it also causes long standing increases

00:25:49.680 | in basal metabolic rate.

00:25:51.180 | Now I'd like to turn to prescription drugs

00:25:53.520 | that regulate the hormone systems

00:25:55.960 | controlling feeding and satiety.

00:25:58.420 | There's a prescription drug, Metformin,

00:26:01.020 | which was developed as a treatment for diabetes.

00:26:03.500 | And it works potently to reduce blood glucose.

00:26:07.240 | It has dramatic effects in lowering blood glucose.

00:26:11.340 | Metformin involves changes

00:26:14.740 | to mitochondrial action in the liver.

00:26:17.320 | That's its main way of depleting or reducing blood glucose.

00:26:22.220 | And it does so through the so-called AMPK pathway,

00:26:25.900 | and it increases insulin sensitivity overall.

00:26:29.620 | Metformin is a powerful drug.

00:26:31.500 | In fact, I'm surprised that so many people

00:26:34.260 | have sought it out given that most of the people

00:26:38.220 | that I'm aware of that sought it out are not diabetic.

00:26:40.640 | I do want to mention,

00:26:42.100 | because I'm sure some of you out there

00:26:43.380 | are curious about the ketogenic diet.

00:26:44.860 | I'm going to do an entire episode

00:26:46.540 | about ketosis and the brain and the body,

00:26:49.220 | but the ketogenic diet has been shown in 22 studies

00:26:54.220 | to have a notable decrease on blood glucose.

00:26:56.340 | And that is not surprising

00:26:57.660 | because the essence of the ketogenic diet

00:27:01.240 | is that you're consuming very little or zero

00:27:04.700 | of the foods that promote big spikes in insulin and glucose.

00:27:08.720 | If you consume enough protein,

00:27:10.920 | some of that protein can be converted into glucose,

00:27:13.700 | of course, through gluconeogenesis.

00:27:15.660 | But the ketogenic diet has very strong support

00:27:18.860 | for its role in regulating blood sugar, which is glucose.

00:27:23.780 | But the specific effects of the ketogenic diet,

00:27:26.980 | and one particular effect that I'll address later,

00:27:29.900 | but I'll mention now,

00:27:31.360 | which is the ability of the ketogenic diet

00:27:34.100 | to adjust thyroid hormone levels

00:27:37.520 | in ways that make it such

00:27:39.060 | that if you return to eating carbohydrates

00:27:41.100 | after being in ketosis for too long,

00:27:43.300 | you don't manage thyroid and carbohydrates as well.

00:27:46.400 | That has been shown as well.

00:27:47.980 | So we're going to dive deep into ketosis in a future episode.

00:27:50.780 | So for you ketonistas out there, don't worry.

00:27:53.340 | I certainly have nothing against ketogenic diet.

00:27:55.700 | I actually don't have anything for or against

00:27:57.860 | any particular nutrition plan.

00:27:59.300 | I know what works for me, at least at this stage of my life,

00:28:01.940 | and I'll update it if I need to.

00:28:03.500 | I'm simply trying to get you as much information

00:28:05.440 | as I possibly can so that you can navigate

00:28:08.260 | through that landscape in a way

00:28:09.860 | that's in keeping with your particular goals.

00:28:13.020 | So now you understand a lot about blood sugar

00:28:15.380 | and how it's managed and the ways that you can manage it

00:28:18.020 | better depending on your particular needs.

00:28:20.900 | This is also a good opportunity for us to look back

00:28:24.360 | at some of the medical literature,

00:28:26.500 | because it really points to just how far we've come

00:28:29.820 | in terms of understanding these important mechanisms.

00:28:32.500 | And it points us in the direction

00:28:34.460 | of some actionable protocols.

00:28:36.940 | So diabetes, which is these huge increases in blood glucose,

00:28:41.940 | because there's no insulin,

00:28:44.520 | was known about as early as 1500 BC,

00:28:47.900 | which is just incredible.

00:28:49.740 | And the way physicians then understood

00:28:54.260 | that certain people had high blood glucose

00:28:56.440 | without actually knowing what blood glucose was,

00:28:58.900 | is that they would take the urine of particular patients,

00:29:01.900 | and they'd find that ants preferably moved toward

00:29:06.260 | and consumed the urine of certain patients and not others.

00:29:10.820 | And they understood that there was something in that urine

00:29:13.820 | that was correlated with a sudden weight loss

00:29:15.940 | and some of the other probably very unfortunate

00:29:18.300 | health symptoms that these people were experiencing.

00:29:21.700 | So they knew that there was something in blood and urine.

00:29:25.320 | Now, this business of measuring blood sugar from the urine

00:29:30.320 | has been something that lasted way beyond

00:29:33.980 | these early stages of, you know, 1500 BC.

00:29:37.200 | Turns out that as late as 1674,

00:29:40.860 | physicians at Oxford University were figuring out

00:29:44.100 | who had pathologically high levels of blood glucose

00:29:47.980 | by analyzing their urine.

00:29:50.420 | And again, they were measuring the sweetness

00:29:52.180 | of their urine, but, and this is medical fact,

00:29:55.180 | they would do this by taking urine samples

00:29:57.060 | from different patients and tasting them.

00:30:00.880 | And they developed an intuitive sense

00:30:04.060 | of what excessively sweet urine was relative

00:30:08.580 | to the other urines that they had tasted.

00:30:10.300 | So for those of you that are in the medical profession

00:30:12.220 | or those of you that are seeking out the medical profession,

00:30:14.940 | do understand this is not done anymore.

00:30:17.640 | And you can also just reflect on how far we've come

00:30:20.920 | in terms of the medical profession itself,

00:30:23.320 | in our ability to measure things from the blood

00:30:25.380 | and measure things from urine without having to ask ants

00:30:29.520 | which urine is sweeter or ask oneself which urine is sweeter.

00:30:34.520 | So indeed we are making progress as a species.

00:30:37.700 | Before we close out today,

00:30:38.920 | I want to talk about one more tool

00:30:40.660 | that many of you will probably find useful.

00:30:43.660 | I certainly have.

00:30:45.180 | I'm a big consumer of caffeine,

00:30:47.400 | although I don't consume a ton of it,

00:30:49.460 | I consume it very consistently.

00:30:50.980 | So I'm big on consuming mate,

00:30:53.700 | which is a strong caffeinated tea.

00:30:56.580 | And I generally do that early in the day.

00:30:59.400 | Although I do delay about two hours after I wake up

00:31:01.700 | for reasons I've talked about in previous episode

00:31:03.700 | to maintain that nice arc of alertness and focus.

00:31:06.620 | Mate, also called yerba mate,

00:31:09.380 | is an interesting compound because unlike coffee,

00:31:13.700 | it has been shown to increase something

00:31:15.060 | called glucagon-like peptide, GLP-1,

00:31:19.120 | and increase leptin levels.

00:31:20.860 | Now, we didn't talk a lot about glucagon today.

00:31:22.860 | Glucagon is really elevated in the fasting state.

00:31:25.820 | I mentioned that it's sort of the opposite of insulin

00:31:28.820 | in kind of rough terms.

00:31:30.700 | That's one way to think about it.

00:31:33.180 | But GLP-1 or glucagon-like peptide one

00:31:37.540 | is increased by ingesting mate

00:31:39.980 | and it acts as a pretty nice appetite suppressant.

00:31:44.060 | Now, I'm not trying to suppress my appetite.

00:31:46.360 | I like to eat, as I mentioned before,

00:31:48.500 | but it works really well to stimulate the brain

00:31:52.180 | and to give you a level of alertness

00:31:55.360 | and to do a lot of the things that coffee does.

00:31:57.420 | It also contains electrolytes.

00:31:59.220 | So we, meaning our neurons and our brain,

00:32:03.660 | run on a variety of factors,

00:32:06.240 | electrical activity and chemical transmission, et cetera,

00:32:08.540 | but they require adequate levels

00:32:10.620 | of sodium, potassium, and magnesium.

00:32:13.060 | Actually, if you were to learn the biology

00:32:16.060 | or the physiology of the action potential,

00:32:17.840 | the firing of a neuron,

00:32:19.180 | something we teach every first-year neuroscience student,

00:32:21.440 | and I'd be happy to teach you if you're interested,

00:32:24.620 | you'll hear about sodium rushing into cells

00:32:27.460 | and potassium entering and leaving cells

00:32:30.620 | in order to allow neurons to communicate.

00:32:32.980 | Electrolytes are critically important

00:32:35.580 | for the function of the nervous system.

00:32:37.740 | And many things that act as diuretics

00:32:40.700 | that promote excretion of water, like caffeine,

00:32:44.480 | can also take electrolytes out

00:32:46.820 | along with in particular sodium.

00:32:48.640 | And sometimes the lightheadedness or the brain fog

00:32:51.040 | that people experience isn't just

00:32:52.640 | because electrolytes are low,

00:32:53.800 | but because they're kind of out of balance.

00:32:56.120 | So I like mate because it has electrolytes, it has caffeine.

00:33:00.320 | It stimulates the release

00:33:01.700 | of this glucagon-like peptide, GLP-1,

00:33:03.720 | and it's been a big help to me

00:33:05.240 | in extending that early morning fasting window

00:33:07.920 | out to about noon or so when I eat my first meal.

00:33:10.840 | It also just tastes really good.

00:33:12.260 | And the fact that glucagon-like peptide one

00:33:15.900 | is enriched or is released more when you drink mate,

00:33:19.980 | and the fact that GLP-1 can regulate blood sugar

00:33:23.480 | in ways that keep your blood sugar

00:33:25.740 | in that we called euglycemic,

00:33:28.640 | not too high, not too low mode,

00:33:30.660 | is one reason why ingesting mate is attractive to me.

00:33:34.800 | So Yerba Mate, GLP-1 can manage in healthy ways,

00:33:39.360 | leptin levels, glucose levels, and glucagon levels

00:33:42.440 | in ways that if it serves you, you might want to try.

00:33:45.800 | So once again, we covered an enormous amount of material

00:33:49.320 | focused on how hormones regulate feeding, hunger,

00:33:53.400 | and when one feels they don't need to eat,

00:33:56.360 | so-called satiety, that you've had enough.

00:33:58.800 | We've just focused today mainly on things like ghrelin,

00:34:02.800 | on things like melanocyte-simulating hormone,

00:34:05.880 | incredible, powerful hormone that can suppress appetite,

00:34:09.560 | on things like cholecystokinin that comes from the gut

00:34:13.160 | and can suppress appetite, on things like food emulsifiers,

00:34:17.120 | on the fact that when you're eating,

00:34:19.120 | you are amino acid seeking,

00:34:21.320 | even though you might not realize it,

00:34:23.000 | that you are also seeking out particular fatty acids.

00:34:26.160 | So I've tried to give you a number of actionable tools.

00:34:28.740 | Again, always do what's best for your health

00:34:30.800 | and do that in company with a healthcare professional.

00:34:33.800 | I'm not a physician, I don't prescribe anything.

00:34:36.080 | I'm a professor, I profess a lot of things.

00:34:38.680 | If you know anyone that's interested in this topic

00:34:41.080 | or you think that someone could benefit from it,

00:34:43.160 | please suggest the podcast to them as well,

00:34:45.320 | and most of all, thank you for your interest in science.

00:34:48.120 | [upbeat music]

00:34:50.700 | (upbeat music)

How to Control Hunger, Eating & Satiety | Huberman Lab Essentials

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