Glycomacropeptide (GMP) is not critical to whey-induced satiety, but may have a unique role in energy intake regulation through cholecystokinin (CCK).
BACKGROUND
Whey protein is more satiating than other protein types, including casein. We hypothesized that enhanced satiety with whey protein is related to glycomacropeptide (GMP) content, a stimulator of cholecystokinin (CCK).


OBJECTIVE
To investigate the role of GMP in whey protein-induced satiety, as measured by subjective satiety, CCK release and food intake at a test meal in healthy weight men and women.


METHODS
In a within-subjects design, twenty subjects (n=10 men, 10 women) consumed 1 of 4 preload shakes (300 mL, 1 MJ), 1 week apart. Preloads differed by protein source and content: Whey; whey protein isolate, Whey (-)GMP; whey protein without GMP, Control; low protein, GMP; GMP isolate. Protein energy of preloads was 44, 44, 2 and 3%, respectively. Subjective satiety and CCK were measured at 0, 15, 30, 45, 60, 75 and 105 min post-preload consumption. A lunch test meal was provided at 75 min. Food records were completed weekly.


RESULTS
Pre-meal satiety was greater after whey protein preloads compared to Control and GMP preloads in women, but no difference was evident in men (sex by preload, p<0.03). CCK concentrations followed a pattern that predicted the subjective satiety in women, but not in men. Test meal intake was not different by preload; however, compensation relative to usual daily intake was achieved after whey-containing- and GMP-containing preloads in women and after GMP and Control preloads in men.


CONCLUSIONS
GMP alone is not critical in pre-meal whey-induced satiety; however, it may have a unique role in compensatory intake regulation managing daily energy intake.
Burton-Freeman
Britt M
BM
Department of Nutrition, University of California, Davis One Shields Ave., Davis, CA 95616, United States. bbfreeman@ucdavis.edu
D000328:Adult; D001069:Appetite Regulation / Q000502:physiology*; D002766:Cholecystokinin / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004435:Eating / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006020:Glycopeptides / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008894:Milk Proteins / Q000737:chemistry / Q000378:metabolism*; D012016:Reference Values; D012527:Satiation / Q000502:physiology*; D013997:Time Factors; D000067816:Whey Proteins
D006020:Glycopeptides; D008894:Milk Proteins; D000067816:Whey Proteins; D002766:Cholecystokinin