Rethinking fat as a fuel for endurance exercise.

Area of Science:

• Sports Science
• Metabolic Physiology
• Nutritional Biochemistry

Background:

• Reduced carbohydrate availability and impaired lipid utilization limit exercise capacity in athletes.
• Glycogen depletion causes cognitive and physical decline despite abundant body fat reserves.
• Current high-carbohydrate fueling strategies hinder fat metabolism.

Purpose of the Study:

• To review new findings on keto-adaptation and its potential to enhance athletic performance.
• To propose that shifting to fatty acids and ketones as primary fuels benefits athletes.
• To explore the role of beta-hydroxybutyrate as a signaling molecule.

Main Methods:

• Review of current literature on nutritional ketosis and keto-adaptation.
• Analysis of metabolic adaptations to low-carbohydrate, high-fat diets.
• Examination of beta-hydroxybutyrate's signaling functions.

Main Results:

• Nutritional ketosis (ketone levels >0.5 mmol/L) achieved by lowering carbohydrate intake and increasing fat intake accelerates fat oxidation.
• Keto-adaptation involves metabolic adjustments for interorgan fuel supply during carbohydrate restriction.
• Beta-hydroxybutyrate acts as a signaling molecule, influencing gene expression and potentially extending performance.

Conclusions:

• Keto-adaptation enhances the body's ability to utilize fat for fuel, potentially improving exercise capacity.
• Restricting dietary carbohydrates to achieve ketosis and increasing fat intake can optimize fat utilization.
• The signaling role of beta-hydroxybutyrate suggests broader performance benefits beyond fuel provision.