© 2015. Context: The independent or interactive effects of vitamin D and calcium on adiposity remain inconclusive. Objective: The objective of this systematic review and meta-analysis was to assess whether vitamin D and calcium supplements cause changes in adiposity. Data Sources: MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials databases were searched for literature published from 1966 to March 2014. Study Selection: A systematic search was conducted for randomized clinical trials with ≥50 participants aged ≥18 years at baseline who had received at least 12 weeks of treatment. Among the inclusion criteria were supplementation with vitamin D with or without calcium and measurement of adiposity (weight, body mass index [BMI], and/or fat mass). Data Extraction: The primary endpoints assessed were changes in weight, BMI, or fat mass. Data Synthesis: Of 953 trials identified, 26 randomized clinical trials (n=12, vitamin D alone; n=10, vitamin D plus calcium versus calcium control; n=4, vitamin D plus calcium versus placebo) with a total of 42 430 participants (median duration, 12 months) met the inclusion criteria. When compared with placebo, vitamin D supplementation had no significant effect on BMI (weighted mean difference [WMD], -0.06 kg/m2; 95% confidence interval [95%CI], -0.14 to 0.03), weight (WMD, -0.05 kg; 95%CI, -0.32 to 0.23), or fat mass (WMD, -0.43 kg; 95%CI, -1.69 to 0.84). Likewise, no significant reduction in BMI (WMD, 0.02 kg/m2; 95%CI, -0.11 to 0.14), weight (WMD, 0.12 kg; 95%CI, -0.24 to 0.49), or fat mass (WMD, 0.12 kg; 95%CI, -0.22 to 0.45) was observed in participants who received vitamin D plus calcium compared with those who received calcium control. Conclusions: Supplementation with vitamin D showed no effect on adiposity measures in adults.