ObjectiveThe purpose of this study was to evaluate the impact of calcium intake on the body composition in postmenopausal women.DesignA partial crossover design was used to study a weight loss treatment consisting of Phentermine hydrochloride (Fastin®, SmithKline Pharmaceuticals, Philadelphia, PA) therapy plus a low energy diet (5040 kJ/d). Forty‐seven obese, postmenopausal Caucasian women (BMI of 30–38 kg/m2) were randomized into two groups, both of which received drug and diet treatment over 6 months. Body composition was assessed by anthropometry and dual energy x‐ray absorptiometry, and food frequency dietary records were collected from all participants at baseline, 3, and 6 months.Resultsall study subjects lostbody weight and body fat due to the drug therapy and a low calorie diet (5040 kJ/d). There were no differences in weight, BMI and total fat between Group I and Group II at baseline. However, mean calcium intake differ significantly between two groups at baseline (P < 0.05). The participants had a 5.12% and 5.90% weight loss (P=0.001) at three months and six months compare to baseline. Compared to baseline BMI was reduced by 5.2 % and 6.00 % at three months and six months. Total fat mass decreased by 5.60% and 13.34% (P=0.001) at three and six months respectively. These results indicate that the weight reduction program was effective for all participants. However, no significant correlation was observed between change in calciumintake from baseline to 6 months and change in weight, BMI and total bodyfat.Center for Health Research, Loma Linda UniversityGrant Funding Source: Center for Health Research, Loma Linda University