Previous studies found global Ghsr-null mice to be resistant to diet-induced obesity when introduced to a high fat diet from an early age (Zigman et al., 2005), an effect that was later reproduced by neuronal ablation of GHSR (Lee et al., 2016) and partly by ablation of GHSR specifically in the ARC AgRP neurons (by crossing AgRP-Cre and Ghsrf/f mice) (Wu et al., 2017). Here, AGRP is linked to obesity due to melanocortin 4 receptor deficiency.