Vitamin D and Reduced Body Weight

Across 3 studies, 2 found neutral effects (small effect size) and 1 found a moderate beneficial effect on body weight when vitamin D was used in combination with Salacia reticulata. The beneficial finding comes from a low-quality review (evidence score 1), whereas higher-quality studies—a systematic review of 15 RCTs (n=962) and a randomized controlled trial (n=163)—reported no significant changes in weight or BMI. Median study duration across the single study that reported it was 112 days (~16 weeks). The most-reported dose was up to 5,000 IU/day (from one study). The evidence base is small and predominantly neutral.

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Only 1 of 3 studies reached statistical significance, and that study was a low-quality review that evaluated vitamin D in combination with another supplement (Salacia reticulata), so the observed weight reduction cannot be attributed to vitamin D alone. The two higher-quality studies (a systematic review and an RCT) showed no significant effect on body weight, suggesting any potential benefit is likely small or context-dependent.