UCP1 and obesity due to melanocortin 4 receptor deficiency: This is evidenced by the observation that VDRKO mice are resistant to diet-induced obesity due to increased expression of Ucp1, 2, and 3, as well as stimulated fatty acid oxidation in both WAT and BAT [99,100], and overexpression of VDR in adipocytes reduces thermogenesis in WAT and BAT, leading to obesity [101].