Previous research had suggested that calcium has the ability to bind fat, leading to the excretion of the latter rather than its absorption into the body.
For instance, in June Onakpoya et al. published a meta-analysis of 7 trials in Nutrition Reviews, which concluded that taking a dietary supplement of 1,000mg of calcium was associated with a body fat reduction of around 2kg per year.
But the authors of that study wrote: “While the findings suggest that calcium supplementation for at least 6 months results in a statistically significant weight loss in obese and overweight individuals, the clinical relevance of this finding is uncertain.”
For the present study, published in the American Journal of Clinical Nutrition, Connie Weaver from Purdue University and colleagues recruited 43 overweight teenagers aged 12-15 during a 3 week summer camp.
Doubling calcium intake
Weaver et al. wrote: “In overweight adolescent boys and girls, we aimed to determine the effect of the doubling of habitual calcium intake to the recommended intake from dairy or calcium carbonate on energy balance and purported mechanisms including fecal fat excretion, macro-nutrient use and parathyroid hormone suppression.”
Subjects comprised 25 girls with a mean BMI in kg/m2 of 33 ± (plus or minus) 5 and 17 boys with a BMI of 28 ± 5.
Half the participants were placed on a controlled diet of 3 meals and 2 snacks a day that included 756mg/day of calcium. The other half followed the same diet but consumed an extra 650mg/day of calcium delivered in either dairy or calcium carbonate form.
At the end of period, the participants then switched to the diet with the different calcium intake level for another 3 weeks, with energy and macro-nutrient intake levels controlled across both diets.
No variation in body fat
Weaver et al. found no variation in body fat and weight between the 2 groups, which they said suggested calcium had little to no effect on weight loss among the teens, with no effects in terms of quantity and source of calcium on energy or fat balance.
Testing of calcium and fats excreted by the subjects also provided no evidence that calcium could assist weight loss by binding to fat in the intestines and preventing its absorption.
The team concluded: “These data lend little evidence to support the proposed mechanisms for the relation between an increase in calcium intake from calcium carbonate or dairy and weight loss or weight maintenance in children.”
Title: ‘Calcium, dairy products, and energy balance in overweight adolescents: a controlled trial’
Source: American Journal of Clinical Nutrition 94: 1159-1160, doi:10.3945/ajcn.111.024141
Authors: C. Weaver, W.W Campbell, D. Teegarden, B.A Craig, B.R Martin, R.Singh, M.M Braun, J.W Apolzan, T.S Hannon, D.A Schoeller, L.A DiMeglio, Y.Hickey, M.Peacock.