Acute stress modifies food choice in Wistar male and female rats.

The present study investigates the effects of acute stress (15 min of swimming/day for three consecutive days) applied at the onset of the dark phase, just before the usual feeding time, on energy intake and more specifically on macronutrient selection, in male and female Wistar rats. The influence of stress regarding corticosterone and insulin kinetics was also examined. In the two experiments (1: food ad lib and 2: two feeding periods/day), three consecutive days of stress reduced daily body weight gain for both sexes. In the first experiment, the reduction in energy intake only occurred during the first 3h after stress. In males the 3h decrease in energy intake affected the three macronutrients, while in females, only the fat intake was decreased. In the second experiment, the stress only affected intake during the first feeding period. Protein, fat and CHO intakes were reduced in males, while in females only the protein and fat intakes were decreased. Unlike males, an increase in fat ingestion was observed in females; this occurred 6h after stress in experiment 1 and during the second feeding period 5h after stress in experiment 2. Stress raised plasma corticosterone levels in both sexes, while plasma insulin levels were decreased. These results demonstrate that the response to stress differed in males and females regarding macronutrient selection. Moreover, stress induced not only a quantitative effect on energy intake but also a qualitative one.