GPR26 and obesity due to melanocortin 4 receptor deficiency: Gpr26−/− mice: increased susceptibility to diet‐induced obesity, increased total body fat amount, increased food intake, decreased circulating ghrelin level, increased circulating insulin level, increased circulating leptin level, increased circulating cholesterol level, increased circulating triglyceride level, decreased energy expenditure, abnormal glucose homeostasis, increased circulating glucose level, impaired glucose tolerance (Chen et al., 2012)