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Bij afvallen doet wei meer vet verbranden en spaart spieren*
Uit deze studie blijkt dat een goede weiproteïne goede diensten kan bewijzen bij het afvallen. 158 deelnemers met een gemiddelde leeftijd van 43 jaar en een BMI van gemiddeld 35 kregen 12 weken lang een dieet waarbij de calorie-inname met 500 verminderd werd. Een groep kreeg 2x daags 10 gram weiproteïne. Na 12 weken waren alle deelnemers gemiddeld bijna 4 kg afgevallen, bij de weiproteïne gebruikers was dit grotendeels vet wat verbrand was in tegenstelling tot de andere gebruikers waarbij het bijna de helft vet en de andere helft spiermassa die verdwenen waren.
A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study
Joy L Frestedt, John L Zenk, Michael A Kuskowski, Loren S Wardand Eric D Bastian
Nutrition & Metabolism 2008, 5:8doi:10.1186/1743-7075-5-8
Abstract (provisional)
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. 
The complete article is available as a provisional PDF.  (Mei 2008)

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