Chronic ICV infusions of MCH into rodents were shown to not only increase food intake, but to also cause obesity (Della-Zuana et al., 2002; Gomori et al., 2003; Ito et al., 2003); while MCH-induced insulin resistance in rats was observed acutely in the absence of weight changes (Pereira-da-Silva et al., 2005). Here, PMCH is linked to obesity due to melanocortin 4 receptor deficiency.