These data implicate KSR2 as a physiological regulator of glucose metabolism during development affecting energy sensing, insulin signaling, and lipid storage, and demonstrate the value of the C57BL/6 ksr2−/− mouse model as a unique and relevant model system in which to develop and test therapeutic targets for the prevention and treatment of obesity, type 2 diabetes, and obesity‐related metabolic disorders. The gene discussed is KSR2; the disease is obesity due to melanocortin 4 receptor deficiency.