As mentioned before, There appears to be various ways whey can assist in fat loss via different mechanisms. I cover them in an article "The Whey to Weight loss" here:

The Whey To Weight Loss!

Glanbia, the makers of Prolibra mentioned below, have concentrated a few of the sub fractions and other compounds found in whey suspected to help with fat loss. Interesting for sure, but I would want to see if the effect is above a good whey isolate, so a control vs whey vs Prolibra study would be more convincing.


Nutr Metab (Lond). 2008 Mar 27;5(1):8

A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study.

Frestedt JL, Zenk JL, Kuskowski MA, Ward LS, Bastian ED.

ABSTRACT: BACKGROUND: This study evaluated a specialized whey fraction (Prolibra, high in leucine, bioactive peptides and milk calcium) for use as a dietary supplement to enhance weight loss. METHODS: This was a randomized, double-blind, parallel-arm, 12-week study. Caloric intake was reduced 500 calories per day. Subjects consumed Prolibra or an isocaloric ready-to-mix beverage 20 minutes before breakfast and 20 minutes before dinner.

Body fat and lean muscle tissue were measured by dual-energy x-ray absorptiometry (DEXA). Body weight and anthropometric measurements were recorded every 4 weeks. Blood samples were taken at the beginning and end of the study. Statistical analyses were performed on all subjects that completed (completer analysis) and all subjects that lost at least 2.25 kg of body weight (responder analysis). Within group significance was determined at P<0.05 using a two-tailed paired t-test and between group significance was determined using one way analysis of covariance with baseline data as a covariate.

RESULTS: Both groups lost a significant amount of weight and the Prolibra group tended to lose more weight than the control group; however the amount of weight loss was not significantly different between groups after 12 weeks. Prolibra subjects lost significantly more body fat compared to control subjects for both the completer (2.81 vs. 1.62 kg P=0.03) and responder (3.63 vs. 2.11 kg, P=0.01) groups. Prolibra subjects lost significantly less lean muscle mass in the responder group (1.07 vs. 2.41 kg, P=0.02). The ratio of fat to lean loss (kg fat lost/kg lean lost) was much larger for Prolibra subjects for both completer (3.75 vs. 1.05) and responder (3.39 vs. 0.88) groups.

CONCLUSIONS: Subjects in both the control and treatment group lost a significant amount of weight with a 500 calorie reduced diet. Subjects taking Prolibra lost significantly more body fat and showed a greater preservation of lean muscle compared to subjects consuming the control beverage. Because subjects taking Prolibra lost 6.1% of their body fat mass, and because a 5% reduction of body fat mass has been shown to reduce the risk of obesity related disease, the results have practical significance."