Obese subjects were assigned to a reduced calorie diet for 12 weeks and receiving daily supplements containing Glanbia's Prolibra ingredient lost an average 6.1 per cent of their body fat mass, report the researchers in the open access journal Nutrition & Metabolism .
"Supplementation with Prolibra during dieting increased the loss of body fat and the retention of lean muscle mass compared to supplementation with an isocaloric control that had a lower calcium and lower protein content," wrote the researchers, led by Loren Ward from Glanbia Research and Development Center.
"Being able to target body fat while retaining lean muscle provides a healthy scenario for weight loss and the potential to decrease body fat," they added.
The study, performed in collaboration with researchers from the Minnesota Applied Research Center (MARC) and the Veterans Administration Medical Center in Minneapolis, supports the efficacy of the company's Prolibra dairy-derived ingredient containing whey proteins, peptides and milk minerals for weight loss and weight management.
The burgeoning weight loss and management market is estimated to already be worth $7bn (€5.2bn) globally.
Testing the hypothesis "Our hypothesis was that by purifying the active ingredients from milk (high leucine proteins, peptides and milk minerals) a supplement could be developed that would have a positive impact on fat loss, aid in retaining lean muscle and retain bone mineral content without needing to increase dietary protein intake above the recommended RDI (0.8 grams per kg per day)," explained the researchers.
Ward and co-workers recruited 158 obese people (BMI 30 to 42 kg per sq. m, age range 25 to 50) to consume a reduced calorie diet (food intake by 500 calories per day).
The participants were then randomly assigned to receive a supplement containing the whey protein ingredient (53 people), an isocaloric ready-to-mix beverage (53 people), or to a third experimental arm (52 people), which the researchers do not describe in this journal submission.
The supplements were taken 20 minutes before breakfast and dinner.
Significant weight loss was observed for both groups, but the researchers noted an insignificant tendency in participants in the Prolibra group to lose more weight than people in the control group.
Indeed, people in the Prolibra group lost 2.81 kg after 12 weeks compared to 1.62 kg for people in the control group.
Moreover, people receiving the dairy-derived ingredient lost less lean body mass compared to control (1.07 versus 2.41 kg, respectively).
"In our study, with an incremental intake of 20 grams protein per day in the Prolibra group (total intake 0.8 grams per kg per day), we observed fat-directed weight loss of 79 per cent (fat loss/(lean loss + fat loss) x 100)," stated the researchers.
Prolibra is a partially hydrolyzed whey protein isolate, high in protein and low in fat and Glanbia's suggested uses for the ingredient include beverages, powdered beverage mixes and snack bars.
Source: Nutrition & Metabolism 2008, 5 :8, doi:10.1186/1743-7075-5-8 "A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study" Authors: J.L. Frestedt, J.L. Zenk, M.A. Kuskowski, L.S. Ward, E.D. Bastian