Short-term high-fat diet's effects on metabolism and long exercise performance

Ingestion of a high-fat diet by endurance-trained athletes results in substantially higher rates of fat oxidation during exercise.

• Higher rates of fat oxidation are observed during submaximal exercise when athletes consume a high-fat diet compared to an isoenergetic high-carbohydrate diet.
• Muscle glycogen sparing occurs alongside increased fat oxidation during the high-fat diet period.
• These changes in fuel utilization favor fat oxidation even when carbohydrate availability is enhanced before and during exercise.
• Despite these modifications in substrate utilization, fat-adaptation followed by carbohydrate restoration does not lead to clear performance benefits in prolonged endurance exercise.

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