Alpha-MSH (melanocyte stimulating hormone) has generally been assumed to be the endogenous ligand acting at the melanocortin-4 receptor (MC4-R), activation of which in the hypothalamus leads to reduced feeding. However, beta-MSH is also capable of activating MC4-R and inhibiting feeding. The researchers found that obese children are more likely to carry a rare variant of so-called beta-melanocyte-stimulating hormone (beta-MSH) than children of normal weight.