New insights reveal that a cell subpopulation of WAT, called beige or brite adipocytes, under alternative activation of macrophages (i.e., M2 polarization) contributes to express uncoupling protein 1 (UCP1) and are engaged in thermogenesis and browning of WAT (as called beige adipocytes), that provides a defense against cold and obesity [6,7,8,9]. Here, UCP1 is linked to obesity due to melanocortin 4 receptor deficiency.