Finding a way to address our hunger is one of the main motivators we have as living beings. But hunger isn't all about your stomach; your brain plays a key role in how you get the message that it's time to refuel. Watch this lesson for details on how hunger works from the brain's perspective.
So you probably know what hunger is. That's something that most of us have felt. It doesn't feel that great. But you might not really have thought about it in terms of a psychology context, and how it's related in that sense is that it's a motivator; it's something that makes us do things. And really, if you think about it, it's pretty clear why it's a motivator. If you think about the last time you were hungry: maybe you were sitting in a meeting and your stomach was growling distractingly and you can't really concentrate, your coworkers are talking, it's going in one ear and out the other because you're hungry and all you can think about is the burrito you're going to just destroy when you get out of that meeting. What hunger is making you do is it's making you not pay that much attention and it's also making you have a real drive to satisfy the hunger by eating. Hunger makes you eat. It's a force that makes you do something. And it's up there with sex as one of the things that's really one of our most powerful motivators.
Hunger and sex together, they determine a lot of how we budget our time and how we think about things. Going out to eat, making plans, going to the grocery store, cooking - this all centers around hunger. Hunger has a big impact on our daily life. And the main reason why this is is that hunger feels bad. It's pretty universally regarded as something that is not a good thing. So we try to make it stop by eating, because unlike some kind of vaguer emotional needs, hunger has got a pretty clear solution: you eat and the hunger goes away. But something that's a little more interesting to think about is why we feel hungry when we do.
And you might think of it as a pretty basic thing. You have your stomach and when it's full you don't feel hungry and when it's empty, or when it has very little food left in, then you feel hunger. That's kind of how most people think about it. We just assume that this is true, but it actually has not that much to do - it has something to do with how much food is in your stomach - but it has a lot to do with a lot of other things. Because if you think about it, you've probably been in this state: maybe after that meeting you did run out and you got your burrito and you destroyed it and it was delicious and you got extra chips; you're totally full. You come back and someone has brought donuts. You see those tasty donuts and you find room for at least, maybe, half a donut. There's no possible way that after that monstrous burrito, your really have more caloric need, but you do find room to eat the donuts anyway. So it's clearly not just, 'Do I need food?' and 'Is my stomach full?'
But there are some other physical factors that affect it, and one of them is the part of your brain that's called the hypothalamus. And what the hypothalamus's involvement in hunger basically is, is that it has two main parts: there's one part that controls or influences when you want to start eating, and there's another that influences when you want to stop eating. And they actually find - this is pretty interesting - they actually find that in lab rats, so if this part of the hypothalamus, the 'start eating' part, is damaged, the rat, even if it's presented with something tasty...I don't know what rats find tasty, but let's imagine it's you...you're presented with this delicious burrito, you would just not eat it because your hypothalamus is not engaged in regulating whether you want to start eating or not.
The hypothalamus is the part of the brain that controls hunger.
And the 'stop eating' part of it...again, in the lab rats, if it's damaged, the rats will just eat and eat and eat until they're horribly obese. That's what would happen if the part of your hypothalamus that makes you stop eating were damaged. And it's pretty cool that these are just random parts of your brain that really have a direct effect on whether you eat.
There's also hormones that affect whether you want to eat or not. One of them is insulin, and that's something that might be familiar to you if you think about people who are diabetic. It's the hormone that regulates blood sugar. And so, if you think about it, if you eat something, that's going to affect your blood sugar because the body processes it and dumps sugar into your bloodstream. And so the insulin interacts with that and can tell your brain how you're doing on blood sugar levels. Your brain can keep track of that. And there's other hormones that your stomach secretes. One of those is called ghrelin. And this is, again, just another signal to your brain that, 'I've eaten,' 'I haven't eaten.' Your brain has lots of ways of keeping track. There's a lot more hormones, but you get the general idea is that they communicate to your brain sort of how you're doing on nutrition and when you've eaten last.
So I've gone over some of the physical factors besides 'is there food in your belly?' that affect hunger. But what are also kind of interesting is the psychological factors because there are some that really have nothing to do with anything going on in your body and are just things that are going on in your brain. And one of these that's really interesting is that in studies of patients with memory loss - so maybe people with severe Alzheimer's or with some sort of amnesia - what researchers have found is that if they come in and they say, 'Do you want this delicious lunch?' the patients will be like, 'Oh yeah, it's lunchtime. I want that.' And so they eat it, it's gone. And half an hour later (this seems a little mean to me) the researchers will comeback and they'll say, 'Hey, do you want some lunch?' and the people with memory loss will be like, 'Eh, sure. Alright. It's lunchtime.' And away it goes again into their bellies. And some of them will even eat three lunches. They found that they would eat on average between 2-3 lunches because they just couldn't remember that they had eaten lunch already. And even as they were asked to rate their hunger levels, they would rate their hunger levels as, actually, a little bit lower after they've eaten 2-3 lunches, understandably, but they would still eat because they thought it was lunchtime. And this is a really important regulator in how we approach food, is that it doesn't always have to do with whether we need to eat, but just has to do with whether we feel like it's lunchtime.
And this obviously comes up in the case with the people with memory loss, but even if you think about yourself, if you eat this giant burrito, and the chips and maybe those donuts that were at the office, you come home and it's dinner time and you probably don't really need any more calories for the day. You're probably done with your 2,000 - you might even be over 2,000 by this point. But it's dinner time and you'll probably eat anyway because that's what, culturally, we're programmed to do. So that's one kind of psychological factor: the idea of the involvement of memory and ritual in food.
Another big one is cultural attitudes toward eating and also toward weight because eating and weight pretty much get equated, at least in our culture, or you can't really talk about one without talking about the other. And what we find, at least in America as things have gone on, we find that we've been valuing lower and lower weights (so thinner and thinner people), while actually, the majority of people in the country are getting more and more overweight. And this is something that really produces a lot of interesting eating patterns, and not maybe normal eating patterns. And that's cultural. So people end up binging or they end up developing other eating disorders like anorexia or bulimia. Anorexics, they are people who don't eat enough; they don't not eat enough because they are hideously overweight and they actually need to lose weight, they don't eat enough because they have an eating disorder. It's not really related to physical need.
But what this reminds us of is how many things go into affecting how a motivator like hunger is turned into an action. It usually is turned into eating, sometimes it isn't, or sometimes it's turned into disproportionate eating. And there's also things - if we want to quickly go back to the weight side of the equation - there's one last physical thing that's important for weight, and that's the idea that people don't have always the same caloric needs as each other, and this has to do with your Basal Metabolic Rate. And what this is, is basically how many calories you burn while you're sitting on the couch. So some people can just sit on the couch and they don't burn very many calories, their bodies are really efficient. They can eat a bag of chips and it doesn't really go anywhere. And these kinds of people would have been great back in the day when there were famines. These are the people you would want to be friends with. But some people will do the same exact activity, they'll sit on the couch and they'll eat a bag of chips, and that bag of chips will just be burnt up because their Basal Metabolic Rate is way higher. And this is something that can really have an effect on weight and hunger and how we interact with food.
It's a really interesting puzzle between hunger and eating and weight; these are all things that seem like they should be pretty straightforward, they should have pretty reliable causational things between them, but they actually don't because they're are so many different factors that are involved. And hopefully I've gone over a few of them and you get a little bit of a better sense of how complicated a picture this actually is and how interesting it is. So yeah, that's hunger.