Forced expression of BMP4 in white adipocytes reduced the mass of white adipocyte tissue (WAT) and the size of white adipocytes in mice, with an increased number of a white adipocyte cell types with brown adipocyte characteristics [16], which closely correlated with increased energy expenditure, improved insulin sensitivity, and protection against diet-induced obesity and diabetes [16]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.