PMCH and obesity due to melanocortin 4 receptor deficiency: MCH, a 19-amino acid cyclic peptide, is a key regulator of food intake and metabolism; Pmch mRNA is upregulated after fasting [5], [6], Pmch-deficient (pmch−/−) rodents are hypophagic, lean, and have a decreased body weight as compared to wild type siblings [7], [8], [9], whereas Pmch overexpression results in hyperphagia and obesity [10].