Regardless of exercise group assignment, calcium adjusted for energy intake had a negative relationship and vitamin A intake a positive relationship with two year changes in total body weight and body fat in young women aged 18 to 31 years. Thus, subjects with high calcium intake, corrected by total energy intake, and lower vitamin A intake gained less weight and body fat over two years in this randomized exercise intervention trial.

Objective: The purpose of this study was to investigate the impact of dietary calcium or dairy product intake on total energy expenditure (TEE), fat oxidation, and thermic effect of a meal (TEM) during a weight loss trial. Methods and Procedures:The intervention included a prescribed 500-kcal deficit diet in a randomized placebo-controlled calcium or dairy product intervention employing twenty-four 18 to 31-year-old (22.2 ± 3.1 years, mean ± s.d.) overweight women (75.5 ± 9.6 kg). TEM and fat oxidation were measured using respiratory gas exchange after a meal challenge, and TEE was measured by doubly labeled water. Fat mass (FM) and lean mass (fat-free mass (FFM)) were measured by dual-energy X-ray absorptiometry. Subjects were randomized into one of these three intervention groups: (i) placebo (<800 mg/day calcium intake); (ii) 900 mg/day calcium supplement; (iii) three servings of dairy products/day to achieve an additional 900 mg/day. Results: There were no group effects observed in change in TEE; however, a group effect was observed for fat oxidation after adjusting for FFM (P = 0.02). The treatment effect was due to an increase in fat oxidation in the calcium-supplemented group of 1.5 ± 0.6 g/h, P = 0.02. Baseline 25-hydroxyvitamin D (25OHD) was positively correlated with TEM (R = 0.31, P = 0.004), and trended toward a correlation with fat oxidation (P = 0.06), independent of group assignment. Finally, the change in log parathyroid hormone (PTH) was positively correlated with the change in trunk FM (R = 0.27, P = 0.03). Discussion: These results support that calcium intake increases fat oxidation, but does not change TEE and that adequate vitamin D status may enhance TEM and fat oxidation.

A 12-week randomized controlled multi-center clinical trial was conducted in 106 overweight and obese adults. Diets were designed to produce a 2,093 kJ/day energy deficit with either low calcium (LC; ~600 mg/day), high calcium (HC; ~1,400 mg/day), or high dairy (HD; three dairy servings, diet totaling ~1,400 mg/day). Ninety-three subjects completed the trial, and 68 met all a priori weekly compliance criteria. Both HC and HD contained comparable levels of calcium, but HC was only ~30% as effective as HD in suppressing 1,25-(OH)2D and exerted no significant effects on weight loss or body composition compared to LC. In the group that met compliance criteria, HD resulted in ~two-fold augmentation of fat loss compared to LC and HC (HD: -4.43 ± 0.53 kg; LC: -2.69 ± 0.0.53 kg; HC: -2.23 ± 0.73kg, p < 0.025); assessment of all completers and an intent-to-treat analysis produced similar trends. HD augmentated central (trunk) fat loss (HD: -2.38 ± 0.30 kg; HC: -1.42 ± 0.30 kg; LC: -1.36 ± 0.42 kg, p < 0.05) and waist circumference (HD: -7.65 ± 0.75 cm; LC: -4.92 ± 0.74 cm; LC: -4.95 ± 1.05 cm, p < 0.025). Similar effects were noted among all subjects completing the study and in an intent-to-treat analysis. These data indicate that dairy-rich diets augment weight loss by targeting the fat compartment during energy restriction.

Increased intake of dairy products does not alter body weight or fat mass in young, healthy women over 1 y.