How Whey Protein May Affect Weight
Researchers say a couple of things may help to explain the weight and fat loss seen with whey protein.
People in the whey protein group had significantly lower blood levels of the hormone ghrelin than people eating the soy protein or carbohydrate.
"It's a hormone that helps regulate food intake," says David J. Baer, PhD, research physiologist at the USDA's agriculture research service in Beltsville, Md. "So the higher concentration, the more hungry somebody feels. The lower concentration, the fuller somebody feels."
And though researchers really can't explain why this happened or what it means, they found that people drinking the whey protein had cut back on their carbohydrate intake by the end of the study, even though they weren't eating fewer total calories and didn't know what kind of supplement they were getting.
Though people drinking soy protein saw little change in their weight or body composition during the study, they had higher levels of thyroid hormones compared to those drinking whey. Thyroid hormones control metabolism and higher levels may indicate a metabolic boost, though more research is needed to fully explain what that may mean for weight loss.
For people who are hoping to replicate the results at home, researchers advise picking a whey product that is also low in calories and fat.
"A lot of the whey products on the market also have a lot of calories in them," Baer says, "Consumers just need to read those labels."