Lee Swanson Research Update

Whey Protein Shows Body Weight Benefits

August 2011

Supplements of whey protein may improve body weight without restricting energy intakes or habitual diets in obese and overweight adults, suggests a new study by scientists from the U.S. Department of Agriculture (USDA).

Fifty-six grams of whey protein (WP) per day for six months were associated with a two percent reduction in body weight, compared to a group consuming an equal amount of calories from carbohydrates, according to findings published in the Journal of Nutrition.

The study, funded by USDA and the U.S. Whey Protein Research Consortium (USWPRC), found that the whey protein supplement was associated with a reduction in levels of a hormone called ghrelin, which is reported to serve as a hunger signal and may boost food intake.

"In this study in which energy restriction was not part of the intervention, changes in body weight and composition were small but nevertheless suggest that habitual consumption of supplemental protein may result in improved body composition and incremental, but ultimately significant, weight-loss," USDA researchers wrote.

"These data suggest that supplemental dietary protein may reduce the risk of unhealthy weight gain observed in many populations (i.e. 500 to 1,000 grams per year)."

Gregory Miller, PhD, president of the Dairy Research Institute (DRI), welcomed the study as adding to the "growing body of research showing a benefit of higher protein diets, and whey protein in particular, on weight management and body composition."

"While a majority of the previously published work has shown this benefit with concurrent energy restriction or routine exercise, this study is unique in demonstrating the gradual benefit of added whey protein without these other lifestyle changes.

"Certainly, to elicit significant changes in body weight over the short term requires exercise or diet adjustments. However, this study provides early evidence that whey protein may play a significant role in weight management over the long term," Dr. Miller added.

USDA researchers recruited 73 overweight and obese adults and randomly assigned them to receive two 200-calorie beverages a day, consisting of 28 grams of whey or soy protein, plus carbohydrate or carbohydrate alone per serving for 23 weeks. No other instructions were provided about diet.

At the end of the study, the researchers report that the whey protein group’s body weight was approximately four pounds lower than the carbohydrate group, and their body fat was five pounds less than the carbohydrate group.

In addition, a one-inch reduction in waist size was reported in the whey group, compared to the carbohydrate and soy protein groups.

"Although there were differences in food intake between males and females, the effects of the intervention were consistent between males and females," the researchers wrote.

"Short-term weight-loss requires energy restriction, and higher protein diets may assist in this acute weight reduction; however, protein supplementation, particularly WP, in overweight and obese individuals may assist in long-term maintenance of body weight without energy restriction."

The Journal of Nutrition; Published online ahead of print.

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