EPOR and obesity due to melanocortin 4 receptor deficiency: Fat specific deletion of EpoR (EpoRaP2KO generated by mating EpoR-floxed mice and aP2-Cre mice on a C57Bl/6 background as a model system for diet induced obesity) preferentially increased body weight and fat mass, and by 30 weeks these mice had 65% greater fat mass with reduced oxygen consumption and total respiratory exchange ratio [30].