TNFRSF11B and obesity due to melanocortin 4 receptor deficiency: Furthermore, obesity is usually accompanied with abnormal secretion of adipokines-adiponectin, leptin, ghrelin, and resistin, which may affect the bone mineral density (BMD) through different pathways such as transforming growth factor-β (TGF-β) signaling, the Receptor activator of nuclear factor kappa-Β ligand (RANKL)/RANK/osteoprotegerin (OPG) pathway, and the Peroxisome proliferator-activated receptor gamma (PPAR-γ) pathway [10].