By Catherine A. Sanderson, Amherst College
Eating is clearly motivated at least in part by basic biological principles: We need to eat in order to survive. So, it makes sense that we pay attention to physiological cues that indicate hunger, which basically tell us ‘It’s time to eat’. But what exactly are these cues? Read on more to find out.
Biological Cues to Hunger
Early researchers believed that stomach contractions or growls—a sign the stomach is empty—trigger hunger. This theory explains why many strategies for helping lose weight are based on ‘tricking the stomach’ into thinking it’s full, such as by drinking lots of water. However, there is indeed some evidence that receptors in the stomach and intestines detect the presence, or lack thereof, of levels of nutrients, which then triggers feelings of hunger.
Interestingly though, research also shows that even people who’ve had their stomachs removed—due to cancer, for example—experience hunger.
Other biological cues to hunger include the body’s biochemistry, levels of glucose as well as particular hormones. For example, when blood glucose levels drop, the liver sends messages to the brain that increase hunger. The pancreas releases insulin, a hormone that helps the cells extract glucose from the blood. Higher levels of insulin predict increased feelings of hunger. Finally, fat cells throughout the body produce the hormone leptin, which gives the hypothalamus information about the body’s fat stores. Low leptin levels tell the body we don’t have enough fat, which in turn triggers feelings of hunger.
This article comes directly from content in the video series Introduction to Psychology. Watch it now, on Wondrium.
Hypothalamus
Research has shown how particular parts of the brain, including the hypothalamus, help regulate biological cues about eating and feelings of hunger. When different parts of the hypothalamus are damaged in experiments using rats, the animals either gain huge amounts of weight or starve to death. So, this tells us that the hypothalamus plays an important role in regulating the motivation to eat.
One explanation for how this process works is that the hypothalamus influences the amount of fat that can be stored in cells, which in turn influences hunger. Another possibility is that the hypothalamus influences levels of glucose or insulin in the blood, which, as previously mentioned, also predict feelings of hunger and fullness.
Clearly, the motivation to eat is determined by numerous interacting processes in the brain and body: our stomach growling, levels of particular hormones in the body, activation of the hypothalamus, and so on. But it’s also quite clear that psychosocial factors play an even stronger role.
Psychosocial Factors
We’ve all eaten when we’re not hungry. And, we’ve all made deliberate choices not to eat something, even when we did feel hungry. These psychosocial motivations to eat are often shaped by various environmental cues.
First, there are external cues—meaning cues from our environment—that often lead us to eat, even when we aren’t hungry. This is like the appearance of a dessert tray that cues people in a restaurant to have some cheesecake. Presenting the dessert tray dramatically increases the likelihood that people will order a dessert. Even seeing pictures of high fat foods—hamburgers, brownies, French fries—stimulates parts of the brain in charge of appetite and triggers cravings for sweet and salty foods.
Another type of external cue is the culture we’re in, which influences when we eat, where we eat, and how much. People in the United States tend to ‘feel hungry’ for dinner around 6 or 7 pm. But people in many European and South American countries tend to eat much later, around 9 or 10 pm. People who eat while sitting in front of a television tend to eat more.
Eating to Regulate Our Moods
Another external cue that influences eating is mood. Researchers at a business school in France conducted a clever study to test this link between feeling sad and eating junk foods. They tracked market data for food consumption in cities with NFL teams and measured how much eating changed after victories versus defeats. Can you predict what they found?
Basically, when our team loses, it’s bad for our waistline. The day after a loss, overall calorie consumption went up about 10% and saturated fat consumption went up by 16%. After a win, people ate fewer calories and consumed healthier foods. The impact of sport outcome was even greater in cities ranked by ESPN and Forbes as having the most dedicated football fans—Philadelphia, Green Bay, Pittsburgh.
These findings fit with what we probably recognize in our own behavior.
Thus, when it comes to understanding how motivation influences our behaviour with regard to eating, the motivation we feel is both biological and psychological.
Common Questions about How Motivation Influences Behavior
Early researchers believed that stomach contractions or growls—a sign the stomach is empty—trigger hunger. This theory explains why many strategies for helping lose weight are based on ‘tricking the stomach’ into thinking it’s full
Research has shown how particular parts of the brain, including the hypothalamus, help regulate biological cues about eating and feelings of hunger.
Seeing pictures of high fat foods—hamburgers, brownies, French fries—stimulates parts of the brain in charge of appetite and triggers cravings for sweet and salty foods.
