After an average of 6 months after bariatric surgery, patients with severe obesity undergoing sleeve gastrectomy or RYGB experienced a profound decrease in body weight, whole-body adiposity and leptinemia and an improvement in insulin sensitivity, as well as a decrease in γ-glutamyltransferase (γ-GT) levels (Table 2). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.