A sampling of tissue‐specific KO experiments shows that mammary glands are more prone to breast cancer,(110) cardiac muscle develops cardiac hypertrophy,(111) the liver becomes fatty (nonalcoholic fatty liver syndrome),(112, 113) the prostate develops hyperplasia,(114) atherosclerosis is accelerated,(115) and mice become resistant to diet‐induced obesity.(116) Conversely, overexpression of the VDR leads to obesity(117) in the mouse, but not in humans.(118) More work is needed to understand how these KO and overexpression models in mice relate to human pathophysiology. Here, VDR is linked to obesity due to melanocortin 4 receptor deficiency.