Liu et al. provided evidence in mice that glucagon-like peptide-1 (GLP-1) expressing neurons in the medulla send anorexigenic signals to the paraventricular nucleus (PVN) of the hypothalamus and that postnatal depletion of GLP-1 receptors in the PVN causes hyperphagic obesity (Liu et al., 2017). The gene discussed is GCG; the disease is obesity due to melanocortin 4 receptor deficiency.