title: The effects of fat and protein on glycemic responses in nondiabetic humans vary with waist circumference, fasting plasma insulin, and dietary fiber intake.
abstract: The effects of protein and fat on glycemic responses have not been studied systematically. Therefore, our aim was to determine the dose-response effects of protein and fat on the glycemic response elicited by 50 g glucose in humans and whether subjects' fasting plasma insulin (FPI) and diet influenced the results. Nondiabetic humans, 10 with FPI < [corrected] or =40 pmol/L and 10 with FPI >40 pmol/L, were studied on 18 occasions after 10 14-h overnight fasts. Subjects consumed 50 g glucose dissolved in 250 mL water plus 0, 5, 10, or 30 g fat and/or 0, 5, 10, or 30 g protein. Each level of fat was tested with each level of protein. Dietary intake was measured using a 3-d food record. Gram per gram, protein reduced glucose responses approximately 2 times more than fat (P < 0.001) with no significant fat x protein interaction (P = 0.051). The effect of protein on glycemic responses was related to waist circumference (WC) (r = -0.56, P = 0.011) and intake of dietary fiber (r = -0.60, P = 0.005) but was unrelated to FPI or other nutrient intakes. The effect of fat on glycemic responses was related to FPI (r = 0.49, P = 0.029) but was unrelated to WC or diet. We conclude that, across the range of 0-30 g, protein and fat reduced glycemic responses independently from each other in a linear, dose-dependent fashion, with protein having approximately 3-times the effect of fat. A large protein effect was associated with high WC and high dietary-fiber intake, whereas a large fat effect was associated with low FPI. These conclusions may not apply to solid meals. Further studies are needed to determine the mechanisms for these effects.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Ontario M5S 3E2, Canada.
authors.forename: Elham
authors.initials: E
authors.lastname: Moghaddam
authors.forename: Janet A
authors.initials: JA
authors.lastname: Vogt
authors.forename: Thomas M S
authors.initials: TM
authors.lastname: Wolever
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001786:Blood Glucose / Q000032:analysis*; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D004041:Dietary Fats / Q000494:pharmacology*; D004043:Dietary Fiber / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000494:pharmacology*; D005215:Fasting; D005260:Female; D006706:Homeostasis; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood
chemical_list: D001786:Blood Glucose; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D004041:Dietary Fats; D004043:Dietary Fiber; D004044:Dietary Proteins; D007328:Insulin; D014280:Triglycerides; D002784:Cholesterol