This one might have gotten started in the mid-2000s, when a study found that obese adults, who ate three 6-ounce (170-gram) servings of fat-free yogurt as part of a reduced-calorie diet, lost 22 percent more weight than dieters who simply cut calories. Even more appealingly, the study, which was funded in part by a company that manufactures yogurt, found that the yogurt eaters lost more fat in the belly area than the control group. And that's what everybody wants, right? The hypothesis was that calcium and protein from low-fat dairy products somehow helped to burn fat and melt off the pounds [source: WebMD].
Thanks, yogurt company! That sounds like a pretty good deal, since yogurt tastes better than some of the other exotic concoctions that dieters are willing to consume. But a study published in 2012 analyzed data from previous studies and found that dairy consumption, in itself, didn't have any significant effect on body weight or fat loss. Also, it had only "modest" benefits as part of a reduced-calorie regimen [source: Chen et al.].