Activity-Based Anorexia: Effects of Force in the Running Wheel on Activity and Body Weight in Rats

Abstract

The animal model of activity-based anorexia (ABA) has helped us make progress in identifying certain variables that affect the food consumption, body weight, and activity of organisms. This study was designed to explore the effects of expending energy on the running wheel on body weight and on activity by rats in the development of activity-based anorexia. Rats were divided into two groups distinguished by the amount of force required to rotate the running wheel (0.12 N vs. 0.96 N). Subjects were kept in experimental chambers for 23.5 hours per day, with 60 minutes of free access to food. For the remainder of the session they were permitted access to the running wheel. Subjects were kept in these conditions until their body weight reached 75%. It was found that the rats in the group requiring a force of 0.12 N maintained a higher level of activity than those in the group requiring a force of 0.96 N. No differences in weight loss were observed between the two groups. These findings are consistent with reports on activity-based anorexia and reinforce the contribution of implied force on activity and body weight