The effects of isocaloric substitution of dietary carbohydrates from whole cereal grains with carbohydrates from white flour and sucrose on body weight gain, body chemical composition, fatty acid profiles, and concentrations of corticosterone and thyroxine (T4), two hormones enhancing or promoting lipolysis, were followed experimentally. The change in source and type of dietary carbohydrates was found to be accompanied by a reduction in the blood corticosterone concentration (from 115.3±54.6 to 44.9±29.8 ng/mL) in males only; the reduction could have facilitated adipose tissue accumulation (body weight gain from 1.22±0.97 per 100g standard diet to 1.68±0.58 g per 100 g modified diet). As, however, the females receiving the modified diet did show increased adipose tissue accumulation as well (from 1.32±0.47 to 2.23±0.80 g per 100 g feed consumed), with only a slight corticosterone concentration increase (from 52.2±20.0 to 67.4±336.7 ng/mL), it seems that the adipose tissue accumulation mechanism in females must have been different. No significant effect of the modified diet on thyroxine concentration was detected.