Have you been told that dairy products like yogurt will help you lose weight? Just search 'dairy and weight loss' online and you'll find a myriad of websites stating dairy aids in weight loss. Women frequently consume yogurt, calcium supplements and dairy products assuming these dietary practices will help them stay slim and lean.
But what does the evidence state? What do researchers find when they observe large groups of people consuming dairy products over a period of time (longitudinal studies) or when scientists test the difference between one group consuming dairy and calcium and the other group isn't (controlled trials)? More importantly when we put all of these findings together (meta-analysis), what kind of picture is painted for the dairy and weight loss hypothesis?
To help answer this question, today I'm reviewing a meta-analysis of 49 randomized trials (1) to help us understand if dairy and calcium products assist in weight loss.
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Amy Lanou, PhD, Chair and associate professor in the Department of Health and Wellness at Univeristy of North Carolina and Neal Barnard, MD, President of the Physician's Committee of Responsible Medicine, published a review 49 randomized, clinical trials in the journal 'Nutrition Reviews.'
Based on inconclusive results of longitudinal studies, the authors reviewed clinical trials to further assess the evidence on dairy, calcium and weight loss with and without calorie restricted diets. Additionally, this review took into account which of the included studies used calorie-restrictive diets in conjunction with the dairy or calcium interventions. Other meta-anlysises of clinical trials have failed to do (2).
The author's search revealed 49 studies. Here's what the results found...
"Forty-one trials showed no significant effect of dairy or calcium on body weight, with or without energy restriction.
Two demonstrated an increase in body weight with a dairy treatment; (9,10) four small trials demonstrated a differential weight loss with calcium supplements and dairy products when paired with a calorie-restricted diet (46,70,71) and another showed a greater rate of weight loss with supplemental calcium in the absence of caloric restriction (38)."
Contrary to popular belief, the totality of evidence shows dairy and calcium have no effect on weight loss.
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2. Winzenberg T, Shaw K, Fryer J, Jones G. Calcium supplements in healthy children do not affect weight gain, height, or body composition. Obesity (Silver Spring). 2007 Jul;15(7):1789-98. Review. PubMed PMID: 17636098.