What role does VDR play in weight loss?

The vitamin D receptor (VDR) is a nuclear receptor activated by calcitriol, regulating genes involved in calcium homeostasis, immunity, and cell proliferation. Regarding weight loss, observational studies and GWAS have linked certain VDR polymorphisms (e.g., FokI, BsmI, TaqI) to BMI, body fat percentage, and insulin resistance. However, effect sizes are small (1–3% variance explained) and findings are inconsistent. Mechanistically, VDR may influence adipogenesis, lipolysis, and thermogenesis in adipose tissue. Vitamin D deficiency is associated with poorer weight loss outcomes, but RCTs do not support a causal effect of vitamin D supplementation on weight reduction. Direct-to-consumer DNA tests reporting VDR variants (e.g., from MyBody-X) currently lack clinically validated utility for personalized weight management. Evidence is primarily mechanistic and population-based, not individual. Caveat: VDR testing should not guide diet or supplement decisions alone; vitamin D status should be assessed via blood 25-hydroxyvitamin D levels.