Maybe milk really does do a body good. A new study in the Journal of Nutrition reports that a diet high in dairy and protein, combined with calorie restriction and daily exercise, built more muscle and trimmed more dangerous belly fat than a low-dairy, low-protein diet.
In research sponsored in part by the dairy industry, McMaster University scientists compared three groups of overweight and obese, but otherwise healthy, premenopausal women, a total of 90 participants. Each consumed either low, medium or high amounts of dairy foods coupled with higher or lower amounts of protein and carbohydrates. The women also exercised seven days per week for four months, a routine that included daily aerobic exercise plus two days of circuit resistance training/weightlifting.
According to the researchers, over four months there were identical total weight losses among the groups, but the higher-protein, high-dairy group experienced greater whole-body fat and abdomen fat losses, greater lean mass gains and greater increases in strength. The lower-protein, low-dairy group lost about a pound and half of muscle, whereas the higher-protein, high-dairy group actually gained a pound and half of muscle-a three-pound difference.
One hundred percent of the weight lost in the higher-protein, high-dairy group was fat. And the participants gained muscle mass, which is a major change in body composition, says Andrea Josse, lead author of the study. The preservation or even gain of muscle is very important for maintaining metabolic rate and preventing weight regain, which can be major problem for many seeking to lose weight.
The higher-protein, high-dairy group also lost twice as much belly fat. Josse notes, Fat in the abdomen is thought to be especially bad for cardiovascular and metabolic health, and it seems-according to what we found in this study-increasing calcium and protein in the diet may help to further promote loss of fat from the worst storage area in the body.
Researchers speculated that an amino acid, leucine, in the whey found in dairy stimulates muscle building. And dairy protein may aid in regulating appetite, while the calcium in dairy may bind with fats in the intestine, so less fat is absorbed by the body.
| How Much Dairy Do You Need? The USDAs MyPlate website www.myplate.gov, based on the latest federal Dietary Guidelines, advises all adults to consume three cups of dairy foods daily. One cup of milk or calcium-fortified soymilk, 8 fluid ounces of yogurt (one regular container), 2 cups of cottage cheese, 1/2 cup of ricotta cheese, 1 1/2 cups of ice cream, 1/3 cup shredded cheese, 2 ounces of processed cheese and 1.5 ounces of hard cheese all count as one cup toward your daily dairy goal. Not all dairy choices are equally healthy, however: The guidelines emphasize the importance of switching to fat-free or low-fat (1%) dairy products. If you usually drink whole milk, try changing gradually: First switch to reduced fat (2%), then low-fat (1%), and finally fat-free (skim). |
A very important point is that these changes were not captured by simple measures of body weight or body mass index, which are the most commonly used measures of dietary success, adds senior author Stuart Phillips, PhD. These women also got fitter and stronger, which greatly reduces their risk of disease.
Susan B. Roberts, PhD, director of Tufts HNRCA Energy Metabolism Laboratory and author of The I Diet www.instinctdiet.com, notes that many previous studies have sought to link dairy consumption to weight loss. This seems to be better than most, she adds. But it is really the weight of multiple studies that is most important.
In 2008, a review of 49 randomized clinical trials testing the effect of dairy products and calcium supplements on body weight concluded that neither plays a key role in weight reduction. Despite dairy-industry claims, 41 of the studies reviewed showed no significant effect of dairy consumption on body weight; only five trials had positive weight-loss results.
TO LEARN MORE: Journal of Nutrition, September 2011; abstract at jn.nutrition.org/content/141/9/1626.abstract.