Activity-Based Anorexia and Food Schedule Induction

Abstract

The term activity-based anorexia refers to the animal model of anorexia nervosa in humans, by which laboratory rats lose weight rapidly and progressively when submitted to a food access regime of 1 h a day and free access to an activity wheel the remainder of the time. This combination of diet and exercise eventually leads the animals into a process of self-starvation that can end up in their death, a reason by which activity-based anorexia is considered analogous of anorexia nervosa in humans, a disease that combines self-imposed food restriction with an excessive increase in physical activity. The best-studied example of schedule-induced behavior is the excessive ingestion of water in animals that are food deprived and for whom the food episodes occur intermittently. Schedule-induced polydipsia is characterized by the consumption of water around the feeding episodes, similarly to what is seen with activity in the phenomenon of activity-based anorexia. The study presented supports the relationship between both phenomena, so that the initial development of excessive drinking facilitates the subsequent development of wheel running. It is suggested that the imposition of very strict feeding episodes could play an important role during the initial stages of the development of anorexia, facilitating the development of hyperactivity that could end up interfering with food ingestion. Prevention for the development of anorexia should focus on a more efficient control of food regimes rather than limiting physical exercise. The adequate scheduling of feeding episodes should reduce hyperactivity, as it follows from its conception as induced behavior.