Recently, we and others demonstrated that serum and skeletal levels of DKK1, but not SOST, are elevated in obese mice20, 30 and in patients with type 2 diabetes mellitus.31, 32, 33 As DKK1 is a potent suppressor of bone formation and bone mass,34, 35, 36 we hypothesized that elevated DKK1 levels may drive obesity‐induced bone loss in mice. The gene discussed is DKK1; the disease is obesity due to melanocortin 4 receptor deficiency.