MC4R is an important regulator of energy balance in humans, as loss-of-function MC4R mutations constitute the most common form of monogenic obesity (1); and more than 150 pathogenic MC4R variants have been identified in patients with severe, early-onset obesity accompanied by hyperphagia, increased linear growth, impaired glucose metabolism (2) and decreased heart rate and blood pressure compared with similarly obese controls (3). Here, MC4R is linked to Obesity.