Furthermore, the negative relationship between ZAG and obesity was further verified in ZAG administration and ZAG knockout mice, which showed that ZAG administration could induce a rapid and significant reduction in body weight in ob/ob and HFD-induced obese mice (36, 37), while ZAG knock-out mice gained more weight than control mice fed by both standard and lipid rich food (38). Here, AZGP1 is linked to obesity due to melanocortin 4 receptor deficiency.