POMC and obesity due to melanocortin 4 receptor deficiency: POMC gene deletion in rodents results in significantly reduced metabolic rate, hyperphagia and obesity, primarily from altered lipid metabolism (Yaswen et al., 1999; Challis et al., 2004), whereas neuronal overexpression of POMC has been shown to reduce food intake and attenuate obesity in ob/ob mice and obese Zucker rats (Li et al., 2003; Mizuno et al., 2003).