One-month treatment of obese patients (body mass index, 39.44 +/- 0.94, measured in kg/m2) with a very-low-calorie diet (VLCD) resulted in a significant weight loss, which was higher in men than in women. In contrast, the decrease of percent fat content was higher in gynoid obese women than in men or women with android fat distribution. In females fat mobilization was depressed at the thigh region where a substantially lower percent decrement of thigh skinfold thickness was demonstrated in comparison with males. VLCD treatment positively affected blood pressure and concentrations of total cholesterol, triglyceride, insulin, and cortisol. Total cholesterol-high-density lipoprotein (HDL) cholesterol ratio remained unchanged and HDL cholesterol in serum significantly declined. Indexes of body fat distribution were not significantly influenced by the short-term treatment by VLCD except waist-hip ratio, which declined in android obese females. VLCD does not decrease a tolerance of physical exercise, as the metabolic response to submaximal workload on a cycle ergometer as well as the responses of cortisol, growth hormone, and prolactin remained unchanged after the treatment.