A Study Published in the June 16, 2009 edition of the Annals of Internal Medicine showed that calcium supplementation in overweight and obese patients have no effect on weight. Overweight or obese (BMI>30) patients were split into two groups, one group took 1500mg of calcium carbonate a day for two years, the other group was given a placebo. After two years there were no differences between the two groups in terms of weight or body fat.