BACKGROUND: Glycomacropeptide (GMP) is a peptide that has been shown to stimulate release of cholecystokinin, which may promote satiety. OBJECTIVE: The aim of this one-year study was to examine whether greater weight loss could be achieved and sustained with a GMP-enriched whey powder supplement compared with a skim milk powder supplement. DESIGN: In a double-blind, randomized, parallel-design study using meal replacements, weight, body composition (determined by dual-energy X-ray absorptiometry), blood pressure, fasting lipids, glucose, and insulin were measured at baseline, 6, and 12 mo. Meal replacements contained 15 g protein from GMP-enriched whey protein isolate (GMP-WPI) or skim milk powder (SMP) and 900 kJ/sachet. Volunteers consumed 2 sachets/d instead of 2 meals for 6 mo and 1 sachet/d for a further 6 mo. Of the 127 participants (95 women, 32 men, 95.5 +/- 15.4 kg, body mass index 33.4 +/- 3.4 kg/m(2), 50.0 +/- 12.4 y), 82 completed the 6-mo study and 72 of those completed the 12-mo study. RESULTS: At 6 mo, weight loss was 9.5 +/- 5.8 kg compared with 11.0 +/- 6.0, GMP-WPI and SMP, respectively, and 9.9 +/- 8.8 kg compared with 10.8 +/- 7.4 GMP-WPI and SMP, respectively, at 12 mo (P < 0.001 compared with baseline, at both timepoints) with no differences between treatments. Total and LDL cholesterol, triacylglycerols, glucose, insulin, and systolic and diastolic blood pressure decreased at 6 and 12 mo (all P < 0.01 compared with baseline with no difference between treatments). HDL cholesterol increased at 12 mo (P < 0.001 compared with baseline). CONCLUSIONS: Meal replacements containing GMP had no additional effect on the overall sustained 12-mo weight loss of 10 kg. There were improvements in cardiovascular disease risk markers.
Keogh JB, Clifton P. The effect of meal replacements high in glycomacropeptide on weight loss and markers of cardiovascular disease risk. Am J Clin Nutr. 2008 June Commonwealth Scientific and Industrial Research Organization, Human Nutrition, Adelaide, South Australia, Australia.