In support of this idea, ablation of GLP‐1 receptors in the adult (using AAV‐Cre injected directly into the paraventricular hypothalamic nucleus) resulted in marked obesity whereas constitutive deletion of GLP‐1 receptors in the paraventricular hypothalamic nucleus (using Sim1‐Cre) failed to alter energy balance (Table 2) (Burmeister et al., 2017; Ghosal et al., 2017; Liu et al., 2017). The gene discussed is SIM1; the disease is obesity due to melanocortin 4 receptor deficiency.