Adipose tissue protein and mRNA expression of Visfatin (PBEF) has not been investigated in a single study design with regard to the relationship to fat distribution, insulin resistance and other metabolic risk factors, especially in morbidly obese individual undergoing weight loss surgery. Therefore, we propose the following specific aims: Investigate the protein and mRNA expression of Visfatin (PBEF) in the peripheral (subcutaneous) and visceral (omentum) adipose tissues of morbidly obese subjects and their relationships to the changes in body composition, fat distribution, insulin sensitivity and time-dependent reversal of co-morbidities following gastric bypass surgery.