UCP1 and obesity due to melanocortin 4 receptor deficiency: Conversely, muscle specific ectopic expression of uncoupling protein 1 (UCP1), the mitochondrial uncoupling protein of brown adipose tissue (BAT), leads to increased energy expenditure, delayed diet-induced obesity development, improved glucose homeostasis, and increased longevity in these UCP1-TG mice [2]–[4].