Background: Some data suggest that increasing calcium intake may help prevent weight gain.
Objective: To test the hypothesis that calcium supplementation can prevent weight gain in persons who are overweight or obese.
Design: Randomized, placebo-controlled trial. Randomization was computer-generated, and allocation was assigned by pharmacy personnel who prepared intervention and placebo capsules. Participants, providers, and those who assessed outcomes were blinded to study group assignment.
Setting: Single research center.
Participants: 340 overweight (body mass index [BMI], 25 to <30 kg/m2) and obese (BMI â‰¥30 kg/m2) adults (mean age, 38.8 years [SD, 10.5]).
Intervention: Calcium carbonate (elemental calcium, 1500 mg/d) (nÂ = 170) or placebo (nÂ = 170) with meals for 2 years.
Measurements: Changes in body weight and fat mass (primary outcomes).
Results: Seventy-five percent of participants completed the trial (78% received calcium; 73% received placebo). There were no statistically or clinically significant differences between the calcium and placebo groups in change in body weight (difference, 0.02 kg [95% CI, âˆ’1.64 to 1.69 kg]; PÂ = 0.98), BMI (difference, 0.32 kg/m2 [CI, âˆ’0.41 to 1.02 kg/m2]; PÂ = 0.39), or body fat mass (difference, 0.39 kg [CI, âˆ’1.04 to 1.92 kg]; PÂ = 0.55). Parathyroid hormone concentrations decreased in the calcium group compared with the placebo group (difference, âˆ’0.71 pmol/L [CI, âˆ’1.28 to âˆ’0.13 pmol/L]).
Limitation: The study took place at a research center, and its sample was mostly women.
Conclusion: Dietary supplementation with elemental calcium, 1500 mg/d, for 2 years had no statistically or clinically significant effects on weight in overweight and obese adults. Calcium supplementation is unlikely to have clinically significant efficacy as a preventive measure against weight gain in such patients.
Primary Funding Source: Office of Dietary Supplements and Intramural Research Program of the National Institutes of Health.