Obesity and an android body fat distribution are related to metabolic disorders. We investigated the interdependences between metabolism, overweight, and body fat distribution in 40 moderately obese men before and after weight-loss. Correlations between metabolic parameters and body mass index (BMI) or waist to hip ratio (WHR) were much weaker in this exclusively obese population than in subjects of all weight categories, but the association between BMI and glucose tolerance (r = -.46, P less than .01) increased significantly after weight-loss. The improvement of metabolic parameters was much stronger in men who achieved normal weight (BMI less than 27 kg/m2) than in those who remained obese (BMI greater than 30 kg/m2, P less than .05). The WHR decreased during the diet (P less than .001), and this decrease and the extent of weight-loss were significantly correlated to an increase in insulin sensitivity (r = -.41, P less than .01) and a decrease in glucose area after an oral glucose load (r = .34, P less than .05). The decrease in apolipoprotein B, total cholesterol, and low-density lipoprotein (LDL) cholesterol was significantly correlated only to the extent of weight-loss (r = .34, .31, and .39, respectively; P less than .05). We conclude that it is best to reach normal weight for the normalization of metabolic aberrations. The reduction of cholesterol appears to be dependent on the extent of weight-loss, while the improvement in insulin sensitivity and glucose tolerance apparently is related to both the extent of weight-loss and to a change toward a less android body fat distribution.