In general, in adipose tissue, Sirt1 promotes lipolysis, decreasing fat storage, and exerts protective action against obesity-induced inflammation [39,40,41]; in the liver it affects fatty acid metabolism and it increases oxidative metabolism [42,43]; in the pancreas it improves glucose tolerance, regulating insulin secretion [44,45]. This evidence concerns the gene SIRT1 and obesity due to melanocortin 4 receptor deficiency.