Even if these data strongly suggest that VDR deletion improves energy homeostasis, there are several caveats: the mice were fed a rescue diet containing large amounts of calcium, which is suspected to regulate energy homeostasis [86]; the VDR gene was ablated from the entire mouse, making it impossible to attribute the overall phenotype to a specific tissue [42,68]; VDR−/− mice develop alopecia, and the resulting reduced insulation could increase energy expenditure to maintain body temperature [87]. The gene discussed is VDR; the disease is alopecia.