There is evidence from cell culture and animal model studies that adipose tissue has both the vitamin D receptor (VDR) and the ability to synthesize 1,25-dihydroxyvitamin D3, the bioactive vitamin D metabolite, and that vitamin D may regulate adipose tissue mass, differentiation and metabolism in ways that might contribute to overweight and/or obesity possibly by effects on lipogenesis and/or adipogenesis [38,39,40,41,42,43]. This evidence concerns the gene VDR and obesity due to melanocortin 4 receptor deficiency.