Activity anorexia is a biologically based self-starvation syndrome that is triggered by diet and exercise routines. The syndrome occurs in several species of animals including rats and humans. For humans who live in affluent parts of the world, type of diet and exercise patterns are largely determined by sociocultural factors. For other animals, diet is a function of food availability, and exercise is mostly due to response feedback or stimulation from the environment. Whatever factors produce it, severe food restriction in combination with excessive physical exercise can lead to what we call activity anorexia. Activity anorexia occurs when food intake declines, and this reduction in caloric intake results in an increase in physical activity. Increased physical activity causes an additional decline in food intake, which further increases activity, and so on. This simple negative feedback loop organizes several diverse research literatures with regard to human anorexia.
Many animals exposed to a significant reduction in caloric intake respond by increasing their physical activity. At first glance this does not seem to make sense. Why would an organism that is challenged by food reduction increase its caloric expenditure? Some animals do, in fact, reduce their energy output when food is scarce. For example, some species (e.g., ground squirrels) that are routinely exposed to food depletion survive by reducing their metabolic rate and by hibernating through periodic famines. Consider, however, an organism that is dependent on a stable year-round food supply. If an environmental catastrophe threatens starvation, the animal that becomes mobile may travel to a new and plentiful food patch. (Blanton S., 1992).
Chaotic dieting, excessive activity, and physiological abnormalities are associated with human anorexia. Willful self-starvation by humans is usually diagnosed as anorexia nervosa (AN), and patients are treated as mentally disordered.....
