The role of palatable food and hunger as trigger factors in an animal model of stress induced binge eating.

OBJECTIVE

Dieting and stress are etiological factors in eating disorders, and dieting strongly predicts stress-induced overeating in the nonclinical population. We developed an animal model of binge eating in sated rats that is evoked by stress, but only in rats with a history of caloric restriction and only if highly palatable food (HPF) is available after stress. This study investigated the effect of known binge triggers, a taste of HPF and of hunger, on this type of binge eating.

METHOD

Female rats were cycled through the R/S protocol but this time were given just a taste of HPF with ad lib regular chow. After another R/S cycle, rats were stressed during restriction (while hungry) and were given HPF and chow.

RESULTS

Although binge eating did not occur if only chow was available after stress, just a taste of HPF sufficed to increase chow intake to more than 160% (p < 0.001) of rats with a history of restriction only, stress-only, or neither. Hunger increased the proportion of chow consumed by both restricted groups, but stress magnified this hunger-induced overeating by increasing HPF intake to 137% of restriction-only rats (p < 0.001).

DISCUSSION

These effects suggest that binge eating in this model is motivated by reward, not metabolic need, and parallels observations of binge triggers described in clinical binge-eating disorders. This strengthens the validity of using this animal model to target the physiology and treatment of eating disorders preceded by dieting and stress.