Medium-chain triglyceridescontain a class of fatty acids found only in very small amounts in the diet; they are more rapidly absorbed and burned as energy than are other fats.¹ For this reason, athletes have been interested in their use, especially during prolonged endurance exercise. However, no effect on carbohydrate sparing or endurance exercise performance has been shown with moderate amounts of medium-chain triglycerides (30 to 45 grams over two to three hours).^{2, 3} Controlled trials using very large amounts of medium-chain triglycerides (approximately 85 grams over two hours) have resulted in both increased and decreased performance,^{4, 5} while a double-blind trial found that 60 grams per day of medium-chain triglycerides for two weeks had no effect on endurance performance.⁶ A controlled study found increased performance when medium-chain triglycerides were added to a 10% carbohydrate solution,⁷ but another study found no advantage of adding medium-chain triglycerides,⁸ and a third trial actually reported decreased performance with this combination, probably due to gastrointestinal distress, in athletes using medium-chain triglycerides.⁹