Effect of high-fat or high-carbohydrate diets on endurance exercise: a meta-analysis.
The purpose of this investigation was to clarify, via a meta-analysis, whether the literature favors a high-fat or a high-carbohydrate diet to yield superior endurance exercise performance. Twenty published trials were analyzed to compare exercise performance under different diets. The average effect size of -0.60 indicated that subjects following a high-carbohydrate diet exercised longer until exhaustion. The training status of subjects (trained vs. untrained) was significantly related to effect size (r = -0.576, P < 0.01) and effect sizes separated between trained and untrained subjects were -0.05 and -2.84 respectively. The test for homogeneity revealed significant heterogeneity among effect sizes (chi2 [19] = 43.30, P < 0.05), indicating all of the trials are not describing the same effect. Given this significant heterogeneity, a conclusive endorsement of a high-carbohydrate diet based on the literature is difficult to make. Highly dissimilar trial protocols are the primary reason for heterogeneity.
Erlenbusch
Matthew
M
Kansas State University, Manhattan, KS 66506, USA.
Haub
Mark
M
Munoz
Kathy
K
MacConnie
Susan
S
Stillwell
Belinda
B
D000222:Adaptation, Physiological; D001642:Bicycling / Q000502:physiology; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D016032:Randomized Controlled Trials as Topic; D012420:Running / Q000502:physiology
D004040:Dietary Carbohydrates; D004041:Dietary Fats