Dietary influences on exercise metabolism, health and endurance performance

• Main Author: Fletcher, Gareth
• Published: University of Birmingham 2017
• Subjects: 612.3; QP Physiology
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.704864

The capacity to oxidise lipid whilst physically active has been associated with markers of metabolic health and exercise performance. In a group of 305 active men and women, this thesis observed a substantial 6 fold inter-individual variability in the capacity to oxidise lipid during exercise, and explains 46% of the variability. This was largely attributed to aerobic capacity, biological sex, self-reported physical activity level and body composition, with new information provided to show that the dietary intake of carbohydrate and fat is also a significant contributor (~3%) to the explained inter-individual variability. Prior research in men, demonstrates that high fat, low carbohydrate diets enhance lipid oxidation during exercise. This thesis demonstrates that, like men, women respond to short-term (5 day) high fat, low carbohydrate diets by considerably (33%) increasing lipid oxidation during exercise. Further, by using a short term hypercaloric ‘fat supplementation’ without carbohydrate restriction diet, which did not alter lipid oxidation during exercise, this thesis suggests that carbohydrate restriction, not increased fat intake, drives the increased lipid oxidation observed during high fat, low carbohydrate diets. Finally, short-term dietary fat manipulation appears to have minimal impact upon markers of metabolic health or endurance exercise performance in the well-trained women studied.