Essentials: How to Control Hunger, Eating & Satiety

**Andrew Huberman** (0:00)
Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health and performance.
I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. This podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. Today, we're going to talk about how hormones impact feeding and hunger, as well as satiety, the feeling that you don't want to eat or that you've eaten enough. Now, it's important to understand that hormones don't work alone in this context. Today, I'm going to describe some hormones that have powerful effects on whether or not you want to eat more or less or stop eating altogether. But they don't do that on their own. They do that in cooperation with the nervous system. The first thing that you need to know about the nervous system side, the neural control over feeding and hunger, is that there's an area of your brain called the hypothalamus. Now, the hypothalamus contains lots of different kinds of neurons doing lots of different kinds of things. There's a particular area of the hypothalamus called the ventromedial hypothalamus. And it's one that researchers have been interested for a long time now in terms of its relationship to hunger and feeding. And the reason is it creates these paradoxical effects. What do I mean by that? What they found was that sometimes lesioning or disrupting the neurons in the ventromedial hypothalamus would make animals or people hyperphagic. They would want to eat like crazy. And other lesions in other individuals or animals would make them anorexic. It would make them not want to eat at all. It would make food aversive. So that means that the ventromedial hypothalamus is definitely an interesting control station for hunger and feeding and satiety, but it doesn't really tell you what's going on at a deeper level. In fact, it's a little bit confusing or paradoxical. It turns out that there are multiple populations of neurons in there. Some are promoting feeding and some are promoting not feeding or not eating. Now, the other neural component of all this that you need to know about actually has to do with your mouth. So there's an area of your cortex. So that's a little bit further up in your brain called the insular cortex. And it processes a lot of different kinds of information, mostly information about what's going on inside you, so-called interoception. The insular cortex has neurons that get input from your mouth, from the touch receptors in your mouth. An insular cortex has powerful control over whether or not you are enjoying what you're eating, whether or not you want to avoid what you're eating, whether or not you've had enough, or whether or not you want to continue eating more. And that has to do, believe it or not, with the touch or sensation of eating. But the key point right now is to know you got these two brain areas, the ventromedial hypothalamus, that's involved in hunger and lack of hunger. And you have this insular cortex that gets input from your mouth and cares about chewing and the consistency of foods and all sorts of interesting things that are just very tactile. And I think most people think about the touch receptors on, excuse me, the taste receptors on the tongue, but we often don't think about the touch or tactile essence of food. Now, let's get back to the ventromedial hypothalamus. Sometimes it makes animals or people want to eat more, sometimes less. So what's going on there? There's a classic experiment that was done in which researchers took two rats and so-called parabiased them to each other. What that meant is that they did a little surgery and they linked their blood supply so that they were forever physically linked to one another and could exchange factors in the blood, but their brains were separate, their mouths were separate, and they essentially did everything separately except that they were linked to one another. So they had to walk together and go to the same places in order to do it.
This parabiosis experiment revealed something really important. When they lesioned the ventromedial hypothalamus in one of the rats that was connected to the other rat, that rat got very, very fat. It's just really obese. The other one, however, got very thin. It actually lost weight. So what does this tell us? This tells us that there's something in the blood that's being exchanged between the two animals because it was their blood supply that was linked. And that tells us that there's hormone or endocrine signals that are involved in the desire to eat and hunger and appetite. And so next we're going to talk about what those endocrine signals are. And then I'm going to immediately point to some entry points that you can use. And you can use these even if you're not parabiased to anything. And that can allow you to time your meal frequency and predict when you're going to be hungry or not. So let's talk about the endocrine factors that regulate feeding hunger and satiety. I'd like to take a quick break and thank one of our sponsors, David. David makes a protein bar unlike any other. It has 28 grams of protein, only 150 calories and zero grams of sugar. That's right, 28 grams of protein and 75% of its calories come from protein. These bars from David also taste amazing. My favorite flavor is chocolate chip cookie dough. But then again, I also like the chocolate fudge flavored one. And I also like the cake flavored one. Basically, I like all the flavors. They're incredibly delicious. For me personally, I strive to eat mostly whole foods. However, when I'm in a rush or I'm away from home or I'm just looking for a quick afternoon snack, I often find that I'm looking for a high quality protein source. With David, I'm able to get 28 grams of protein with the calories of a snack, which makes it very easy to hit my protein goals of one gram of protein per pound of body weight each day. And it allows me to do that without taking in excess calories. I typically eat a David bar in the early afternoon or even mid afternoon if I want to bridge that gap between lunch and dinner. I like that it's a little bit sweet, so it tastes like a tasty snack, but it's also given me that 28 grams of very high quality protein with just 150 calories. If you would like to try David, you can go to davidprotein.com/huberman.