Effect of repeated stress on body weight and body composition of rats fed low- and high-fat diets

Exposure to the moderate stressor of 3-h restraint for 3 consecutive days c auses a temporary drop in food intake but a permanent reduction in body wei ght in adult rats. Young rats did not show the same response. Food intake o f adult rats exposed to repeated restraint was significantly lower than tha t of controls for 4 days after the end of stress, and there was no rebound hyperphagia. Body weight remained significantly lower for at least 40 days after stress. When the rats were fed a high-fat diet of 80% chow and 20% ve getable shortening (48% kcal fat, 16% protein), lean body mass accounted fo r all of the weight loss in stressed rats. When the experiment was repeated with a purified high-fat diet containing corn oil and coconut oil as the s ource of fat (41% kcal fat, 16% protein), weight loss consisted of both lea n and fat tissue. There were no sustained changes in single time point meas ures of corticosterone, insulin, or leptin that could account for the reduc ed body weight in these rats.