People in certain kinds of occupations like athletes, gymnasts, dancers, and models tend to be excessively concerned about their weight. When they go on diets, they are especially vulnerable to anorexia nervosa because they engage in a high level of physical activity. You have to be careful. Once it gets to a certain level, a vicious circle comes into effect. We started to work on this model about five years ago.
Rats run spontaneously in the wheel, even more when they are hungry.
Rats will also learn to press a lever to gain the opportunity to run in the wheel, and they press more vigorously when they are hungry. These findings indicate that wheel running is rewarding to a rat and that its reward value is increased when the rat is hungry. That wheel running is rewarding implies that it activates a reward system in the brain. Lots of things, such as eating tasty food or having sex, are presumed to do so. Wheel running, at least for rats, is just one of these things.