PRDM16 and obesity due to melanocortin 4 receptor deficiency: Since BMD cannot alone predict the risk of bone fragility, this review explores potential new methods or agents to promote the adipo-myogenic/osteogenic lineage shift which may include but not limited to targeting Prdm16, stem cell therapy, si-RNA inhibitors and repurposing of an old drug, testosterone in the general population of patients with obesity, T2DM or both.