The purpose of this study is to examine the effect of exogenous ketone body supplementation on carbohydrate metabolism during exercise. In a randomized, crossover, and double-blind study, 20 endurance trained adult males and females aged 18-50 years, will ingest carbohydrates with either a ketone monoester supplement before and throughout a 3-hour exercise session or carbohydrates with a flavour-matched ketone-free placebo. The main aim of this study is to compare the exogenous carbohydrate oxidation rates during exercise between the ketone monoester and placebo conditions.

Inclusion Criteria:

• 18-50 years of age
• Trained cyclist/triathlete (VO2peak > 55 ml/kg/min for males and >48 ml/mg/min for females)
• Healthy as per medical history and investigator's/physician's judgement
• Having given written informed consent

Exclusion Criteria:

• Use of medication that could impact study outcomes and/or interfere with the expected mechanism of action of ketone supplements (e.g. Chronic use of gastric acid suppressing medication, statins, corticosteroids)
• Smoking
• Diagnosed acute or chronic medical conditions that, in the opinion of the investigator, could impact study outcomes (e.g. Diabetes mellitus)
• Diagnosed musculoskeletal disorders
• Adhering to a carbohydrate restrictive diet
• Participation in another study at the same time
• Blood donation in the 2 months before the first experimental trial
• Plasma donation in the 2 weeks before the first experimental trial
• Males: VO2peak <55 ml/min/kg body mass
• Females: VO2peak <48 ml/min/kg body mass
• Females: pregnancy

Data will be made available upon request

Color and flavor matched placebo