Virginia Grant and Bow Revusky of the Psychology department look on as graduate student Jennifer Smith gives one of the rats a chance to run on the wheel in the laboratory. A pair of psychologists at Memorial are using rats and running wheels to study the relationship between intense physical activity and the development of anorexia nervosa. Activity anorexia is experimentally induced by allowing rats to eat for 60 minutes each day and leaving them to spend the rest of the day in a running wheel. The rats do not have to run in the wheel but some spend almost all day running.
Rats tend to increase their running over days and their eating is inadequate.
It is not just that they don't eat enough to compensate for their exercise. They actually eat less than other rats that have the same feeding schedule but are not allowed to run in the wheel. The rats that are allowed to run in the wheel lose a lot of weight. 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.