title: Glycomacropeptide (GMP) is not critical to whey-induced satiety, but may have a unique role in energy intake regulation through cholecystokinin (CCK).
abstract: 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.
authors.affiliation: Department of Nutrition, University of California, Davis One Shields Ave., Davis, CA 95616, United States. bbfreeman@ucdavis.edu
authors.forename: Britt M
authors.initials: BM
authors.lastname: Burton-Freeman
mesh_terms: 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
chemical_list: D006020:Glycopeptides; D008894:Milk Proteins; D000067816:Whey Proteins; D002766:Cholecystokinin