What is hunger? Homeostatic vs. hedonic

Before we begin, it’s important to understand exactly what hunger is — what’s going on inside your brain and body that makes you say, “I’m hungry”?

As it turns out, feeling hungry can mean at least two things, and they are pretty different, said Michael Lowe, a professor of psychology at Drexel University in Philadelphia.

Of course, there’s the traditional concept of hunger: when you haven’t eaten in several hours, your stomach is starting to grumble and you’re feeling those usual bodily sensations associated with hunger, Lowe said. This feeling of hunger stems from your body’s need for calories; the need for energy prompts the signal that it’s time to eat, he said.

Researchers refer to this type of hunger as “homeostatic hunger,” Lowe told Live Science.

Homeostatic hunger is driven by a complex series of signals throughout the body and brain that tell us we need food for fuel, said Dr. Amy Rothberg, director of the Weight Management Clinic and an assistant professor of internal medicine in the University of Michigan Health System’s Division of Metabolism, Endocrinology and Diabetes.

Hormones in the body signal when energy stores are running low. When this occurs, levels of ghrelin (sometimes referred to as the “hunger hormone”) start to rise, but then become suppressed as soon as a person starts eating, Rothberg said. In addition, as food travels through the body, a series of satiety responses (which signal fullness) are fired off, starting in the mouth and continuing down through the stomach and the small intestine, she said. These signals tell the brain, “Hey, we’re getting food down here!”

And up in the brain, another series of signals is at work, Rothberg said. These are the sets of opposing signals: the hunger-stimulating (“orexigenic”) peptides, and the hunger-suppressing (“anorexigenic”) peptides, she said. These peptides are hormones that are responsible for telling the brain that a person needs to eat or that a person feels full.

Unsurprisingly, the best way to get rid of homeostatic hunger is to eat.  “And your best bet to maintain that full feeling for a healthy amount of time is to eat nutritious foods that, well, fill you up, Rothberg told Live Science. [Diet and Weight Loss: The Best Ways to Eat]

A diet that contains fiber and lean protein is very filling, Rothberg said. And protein is the most filling of the macronutrients, she said. Indeed, a recent meta-analysis study in the Journal of the Academy of Nutrition and Dietetics concluded that eating larger amounts of protein does increase feelings of fullness compared to eating smaller amounts of protein. [Which Types of Foods Are the Most Filling?]

But it’s also important to be careful about certain foods. “Zero-calorie sweeteners, for example, can confuse fullness signals and trick your brain into thinking you haven’t eaten much when you actually have, thus leading you to eat more, Rothberg said. (There is much debate among health experts about the effects of these sweeteners in the body. For example, although they may help people control their blood sugar levels, evidence is mixed on whether they help people lower their calorie intake or lose weight. In our interview with her, Rothberg was referring specifically to how zero-calorie sweeteners may impact feelings of hunger and fullness.)

Another food group to be careful about is ultra processed, which are loaded with fat and sugar. People don’t just eat for calories, they eat for pleasure, but foods like these can drive the brain to want more of them, essentially overpowering the normal fullness signals firing in the brain, Rothberg said.(Ultraprocessed foods are those that, in addition to sugar, salt, oils and fats, include additives like emulsifiers, flavors and colors — think potato chips or frozen pizza.)

Of course, if people only ate because their bodies needed calories, things would be simple. But that’s not the case.

People “don’t eat necessarily because of the signals that govern our energy stores,” Rothberg said. Rather, sometimes, you just want food.

This type of hunger is called “hedonic hunger.” But hedonic hunger — wanting to eat, dwelling on food or maybe craving something — isn’t nearly as well understood as homeostatic hunger, Lowe said. The term “hedonic hunger” was coined in 2007 in a review led by Lowe and published in the journal Physiology & Behavior.

The most widely accepted theory about hedonic hunger is that the human predisposition to highly palatable foods, which humans developed long ago, has run amok in the modern environment, with the wide availability of really delicious foods, Lowe said. People want to eat even when they don’t need to, he said. And the more often people eat highly palatable foods, the more their brains learn to expect and want them, he said. You can call that hunger, but the reason for that “hungry” feeling appears to have much more to do with seeking pleasure than with needing calories, he said.

But it’s important for people to realize that pleasure plays a role in all types of eating, Lowe said. Pleasure is relevant to both homeostatic and hedonic eating, whereas the need for calories only comes into play during homeostatic eating, he said. For example, when someone is homeostatically hungry, that person is motivated by both the calories and the pleasure that eating brings, he said. Someone who is hedonically hungry, on the other hand, is motivated only by pleasure, he said.

The two types of hunger are not completely distinct but rather represent two ends of a continuum, Lowe said. Certainly, there are cases of hunger that fall at each end of the spectrum: A person who hasn’t eaten in 12 or more hours is experiencing homeostatic hunger, whereas a person who wants dessert after finishing a filling meal is experiencing hedonic hunger. But there isn’t a specific point where someone could say their hunger has switched from being motivated by calories to being motivated purely by pleasure, he said.

Even if a person can recognize whether their hunger is more of a hedonic hunger than a homeostatic hunger, hedonic hunger can still be a little harder to fight.

The best practice for fighting hedonic hunger is to keep those highly palatable, tempting foods out of the house, Lowe said. But if you don’t want to clear your pantry, another tip is to try to curb the desire by eating something “less damaging” — for instance, a piece of fruit instead of a piece of candy — and then seeing if you still want something sweet, he said.

Finally, keeping treats in portion-controlled servings also may help, Lowe said. For example, instead of keeping a half gallon of ice cream in the freezer, buy chocolate ice pops or ice cream sandwiches, and eat just one, he said.

 

References

The Science of Hunger: How to Control It and Fight Cravings. livescience.com. https://www.livescience.com/54248-controlling-your-hunger.html

Hedonic hunger: a new dimension of appetite? – PubMed. (2007, July 24). PubMed. https://doi.org/10.1016/j.physbeh.2007.04.006