Research Review By Novella Martinello©

Date Posted:

May 2010

Study Title:

Dairy and weight loss hypothesis: An evaluation of the clinical trials

Authors:

Lanou AJ & Barnard ND

Author's Affiliations:

University of North Carolina at Asheville, Department of Health and Wellness, Asheville, North Carolina; Physicians Committee for Responsible Medicine, Washington, DC, USA.

Publication Information:

Nutrition Reviews 2008; 66(5): 272-279.

Background Information:

There has been consistent debate about whether dairy products and calcium assist in weight and fat loss. Some cross-sectional studies have shown dairy and calcium to be inversely related to body weight, but results from longitudinal studies investigating this issue have been mixed. An observed effect of calcium or dairy on body weight or fat may be due to a food pattern that is conducive to achieving and maintaining a healthy weight.

Some food-pattern studies reinforce the notion that single foods or nutrients are unlikely to - by themselves - be responsible for weight loss or gain. The associations observed in longitudinal studies suggesting a benefit of dairy products or calcium may be due to the convergence of higher dairy intakes with healthy diets or other positive and healthy lifestyle behaviors.

There has been one systematic review and meta-analysis (1) of 13 randomized clinical trials addressing whether increased calcium intake through supplements or dairy products is associated with weight loss in adults, but did not address the question of whether the weight-loss effect occurs in the context of energy restriction.

To further assess whether calcium or dairy supplementation can be used for weight or body fat loss, the authors reviewed clinical trials addressing calcium or dairy supplementation in adults or children with or without energy-restriction (dieting).

Pertinent Results:

Of eighteen trials conducted in children or adolescents, seven used dairy treatments, while eleven used calcium supplements. None of the seven dairy trials or 11 calcium trials with children or adolescents demonstrated an effect on body weight or, when measured, body fat. These trials varied in length (3 months to 2 years), amount of dairy and calcium supplementation, sample size, and study location.

Of twenty trials conducted in adults without energy restriction, ten tested the effects of dairy products and ten studied calcium supplements. Thirty-seven of 38 clinical trials of dairy product or supplemental calcium intake in the absence of energy restriction did not support an effect of weight loss. Two trials using dairy treatments showed increased weight gain among participants, as compared to controls (2, 3). One calcium supplementation trial observed a small effect on the rate of weight gain over 3 years (4) and a second calcium supplementation trial observed increased weight loss among postmenopausal women over a period of 4 years.

The studies ranged in sample size, amount of dairy intake and calcium supplementation, and length of time.

Eleven clinical trials with adults have assessed whether dairy products or calcium supplements facilitate weight loss in the context of a reduced-energy diet. Of the eleven trials, seven found no effect, while four found a significant positive association between dairy or calcium and weight loss. Of these eleven trials, six investigated the possibility that dairy products facilitate weight loss among overweight and obese adults when paired with a reduced energy diet.

Fifteen of the 16 clinical trials that measured body fat in the absence of energy restriction showed no difference in body fat change between high-dairy or high-calcium treatment in controls versus adults or children and adolescents.

If the trials with sample sizes under 50 and those with increases in calcium intake <400 mg a day are excluded from the analysis so that only the studies with stronger designs are included, the findings remain unsupportive of a relationship between dairy or calcium and weight loss.

Clinical Application & Conclusions:

Current evidence does not support the hypothesis that dairy or calcium consumption alone, or combined with caloric restriction, results in weight or fat loss in the short or long term. It should be noted that this does not mean that dairy products and calcium supplementation do not have appropriate roles in diet and supplementation planning for your clients.

Study Methods:

  • The search strategy included a MEDLINE search for human studies published in English from 1966 to August 2007.
  • Search terms included key words: milk, dairy, calcium and weight, BMI, or body fat.
  • Additional articles were identified from the references of these reports and from the National Dairy Council website. Reports available only in abstract form and those that did not address change in body weight, BMI, or body fat were excluded.
  • The search resulted in 49 clinical trials, 38 observing the effect of dairy products or calcium on bone health, weight, BMI and/or body composition in the absence of energy restriction. Eighteen were conducted with children and adolescents and 20 with adult populations. The remaining 11 studies assessed the effect of calcium or dairy supplementation along with energy restriction on weight.
  • Clinical trials were categorized based on use of an energy restriction protocol, age, and whether it involved dairy products, calcium supplementation, or both.
  • Some weight gain is normal during youth, so these trials of the effect of dairy or calcium on weight gain address whether the addition of dairy products may prevent obesity or excess weight gain. Studies with adults, on the other hand, address either potential weight accrual or weight loss.

Study Strengths / Weaknesses:

Some authors have debated the interpretation of the results in this study. Please see:
Tremblay, A. Letter to the editor. Nutrition Reviews, 2008; 66(9); 544-545.
Zemel, MN. Letter to the editor. Nutrition Reviews, 2008; 66(9); 542-543.

Additional References:

  1. Winzenberg T, Shaw K, Fryer J, Jones G. Calcium supplements in healthy children do not affect weight gain, height, or body composition. Obesity 2007;15:1789–1798.
  2. Lau EMC,Woo J, Lam V, Hong A. Milk supplementation of the diet by postmenopausal Chinese women on a low calcium intake retards bone loss. J Bone Miner Res 2001;16:1704– 1709.
  3. Barr SI, McCarron DA, Heaney RP, et al. Effects of increased consumption of fluid milk on energy, nutrient intake, body weight, and cardiovascular disease risk factors in healthy older adults. J Am Diet Assoc 2000;100:810–817.
  4. Caan B, Neuhouser M, Aragaki A, et al. Calcium plus vitamin D supplementation and the risk of postmenopausal weight gain. Arch Intern Med 2007;167:893–902.