BID and obesity due to melanocortin 4 receptor deficiency: BCL‐2 family proteins were initially discovered through their function in regulating apoptosis.[7] BID belongs to the BH3‐only subfamily of the BCL‐2 molecules and is known to possess a pro‐apoptosis and pro‐proliferation function.[9, 10, 11] We show here that BID has a function in promoting diet‐induced obesity and metabolic syndrome.