ESRRA and obesity due to melanocortin 4 receptor deficiency: Consistent with its role in cellular metabolism, mice deficient in ERRα have increased metabolism, are resistant to diet-induced obesity and are unable to adapt to cold temperatures.7–9 In particular, ERRα is necessary for response to physiological stress as well as for fate and determination of myocytes, adipocytes, T cells, osteoblast and intestinal epithelia.10–14