A study published in The Journal of Nutrition June 2011 showed that whey protein may be helpful in weight loss.
They assigned 90 overweight and obese men and women with an average weight for men of 218 pounds and 190 pounds for the women to 1 of 3 groups. All the groups had an average daily caloric intake of 2,200 calories per day.
The first group added whey protein drinks to their normal diets, the second soy protein, and the third group added carbohydrate drinks. All the drinks had 52 grams per packet of protein or carbohydrates and all the drinks totaled 200 calories each. They were to be drunk at breakfast and dinner. None of the participants knew which type of shake they were drinking. Participants were also to keep a food diary.
After 6 months, they observed that those who drank the carbohydrate shakes gained 2 pounds, the weight of those who drank the soy shakes remained about the same, and those who drank the whey protein shakes lost 2 pounds but also lost about 1 inch around their waistlines.
The soy protein group was found to have higher levels of thyroid hormones, which may have accounted for the maintenance of their weight despite the added calories. Thyroid hormones are known to increase metabolism.
The whey protein group had significantly lower levels of the hormone that regulates food intake, ghrelin. Higher blood concentration of ghrelin correlates with increased hunger. An inexplicable finding was those on whey protein shakes ate less carbohydrates by the end of the study though their total caloric intake did not change.
Be advised to read labels as whey products are high in fat and calories.