EPO and obesity due to melanocortin 4 receptor deficiency: The ΔEpoRE-mice gains body weight and fat mass with age because of lack of Epo signaling in non-hematopoietic tissues.8 Increased fat mass is associated with lower BMD in mice35 and in humans obesity is reported to show low bone formation.36 Compared to body weight matched wild-type mice, the ΔEpoRE-mice had reduced trabecular bone ruling out the role of body weight as a factor for reduced bone phenotype.