The aim of the study was to investigate the relationship between insulin resistance and body composition in relation to secterion and expression of adipocytokines. Obese subjects undergo 6 months hypocaloric diet without any medication and, before, during and at the end of the diet, plasma samples and subcutaneous adipose tissue samples are obtained for subsequent analysis. Adipose tissue samples are obtained using needle biopsy. In addition, before and during the diet,body composition is measured using multifrequency bioimpedance and insulin resistance is evaluated using either hyperinsulinemic clamp or glucose/insulin - derived indices.