Androgens, estrogens and their anti-hormones: Effects on body weight and food consumption

The estrogenic and androgenic effects on food-intake and body weight were examined over a 30-day period in male rats. From Day 8 to 21, animals were maintained on a 23-hr food-deprivation schedule in order to minimize possible between-group differences in food motivation. Food intake was measured during this period. From Day 22 to 23, animals were given free access to a fixed amount of food which was somewhat in excess to that consumed by each group during the previous 1-hr feeding period. Under this condition differences in body weight or weight gain could be assessed in terms of differences in metabolism since food-intake was the same for all groups. Body weights were measured about every 7th day. The effects of testosterone, dihydroxytestosterone and cyproterone acetate as found in this study would suggest that androgens increase food motivation, while testosterone may influence weight gain through its anabolic properties. Estrogen-treatment was found to decrease food-intake, body weight and weight gain. 19-Hydroxytestosterone, which is converted to estrogen in the brain but is without effect on peripheral systems (e.g., adrenals) was without effect on any of the measures studied. Cyproterone acetate had an estrogenic effect only on weight-gain while the anti-estrogen, nafoxidine, mimicked the estrogenic effect only for food-intake. The findings suggest that the estrogenic effects on food-intake and body weight may be due to two separate mechanisms.