AZGP1 and obesity due to melanocortin 4 receptor deficiency: Moreover, the relationship between ZAG and obesity was further supported by ZAG administration and ZAG loss-of-function experiments in HFD-induced obese or ob/ob mice, which showed that ZAG administration could induce significant reductions in body weight and body fat mass (Russell and Tisdale, 2010), while ZAG knock-out mice gained more weight than normal mice fed with either standard food or lipid-rich food (Rolli et al., 2007).