Visceral fat obesity (VFO) with predominant intra-abdominal fat accumulation has been shown to be more often associated with metabolic disorders than subcutaneous fat obesity (SFO). In the present study, changes in fat distribution and their effects on metabolic complications were investigated in forty premenopausal female obese patients in whom substantial weight reduction was obtained by means of a low calorie diet. Analysis of fat distribution by CT scanning demonstrated that visceral fat decreased to a greater extent than abdominal subcutaneous fat, which was particularly evident in VFO patients. On the other hand, change of fat distribution was small in SFO patients. That is, visceral to subcutaneous abdominal fat ratio (V/S ratio) decreased from 0.62 +/- 0.36 to 0.46 +/- 0.33 in VFO, whereas from 0.23 +/- 0.07 to 0.20 +/- 0.09 in SFO after weight reduction. Although obese patients, especially those with VFO, were frequently associated with glucose intolerance and hyperlipidemia, marked diminution was observed in the elevated levels of plasma glucose area on 75g OGTT, serum total cholesterol and triglyceride after weight reduction. By the examination of interrelationship between the changes in body weight, BMI, total and regional fat volume and changes in glucose and lipid metabolism, we found that the decrease in the V/S ratio and visceral fat volume were more strongly correlated with the improvement in plasma glucose and lipid metabolism compared to the decrease in body weight, BMI, total fat volume and abdominal subcutaneous fat volume. Furthermore, partial correlation analyses demonstrated that the metabolic improvements were associated with changes in visceral abdominal fat after control for changes in total adipose tissue volume.(ABSTRACT TRUNCATED AT 250 WORDS)