Nutritional ketone salts increase fat oxidation but impair high-intensity exercise performance in healthy adult males

Appl Physiol Nutr Metab. 2017 Oct;42(10):1031-1035. doi: 10.1139/apnm-2016-0641. Epub 2017 Jul 27.


This study investigated the impact of raising plasma beta-hydroxybutyrate (β-OHB) through ingestion of ketone salts on substrate oxidation and performance during cycling exercise. Ten healthy adult males (age, 23 ± 3 years; body mass index, 25 ± 3 kg/m2, peak oxygen uptake, 45 ± 10 mL/(kg·min)-1) were recruited to complete 2 experimental trials. Before enrollment in the experimental conditions, baseline anthropometrics and cardiorespiratory fitness (peak oxygen uptake) were assessed and familiarization to the study protocol was provided. On experimental days, participants reported to the laboratory in the fasted state and consumed either 0.3 g/kg β-OHB ketone salts or a flavour-matched placebo at 30 min prior to engaging in cycling exercise. Subjects completed steady-state exercise at 30%, 60%, and 90% ventilatory threshold (VT) followed by a 150-kJ cycling time-trial. Respiratory exchange ratio (RER) and total substrate oxidation were derived from indirect calorimetry. Plasma glucose, lactate, and ketones were measured at baseline, 30 min post-supplement, post-steady-state exercise, and immediately following the time-trial. Plasma β-OHB was elevated from baseline and throughout the entire protocol in the ketone condition (p < 0.05). RER was lower at 30% and 60% VT in the ketone compared with control condition. Total fat oxidation was greater in the ketone versus control (p = 0.05). Average time-trial power output was ∼7% lower (-16 W, p = 0.029) in the ketone condition. Ingestion of ketone salts prior to exercise increases fat oxidation during steady-state exercise but impairs high-intensity exercise performance.

Keywords: beta-hydroxybutyrate; bêta-hydroxybutyrate; cétones; cétose; ketones; ketosis; metabolism; métabolisme; oxydation des substrats; substrate oxidation.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • 3-Hydroxybutyric Acid / blood
  • Adult
  • Bicycling
  • Blood Glucose / metabolism
  • British Columbia
  • Cross-Over Studies
  • Dietary Supplements* / adverse effects
  • Double-Blind Method
  • Exercise*
  • Humans
  • Ketones / administration & dosage*
  • Ketones / adverse effects
  • Ketones / blood
  • Lactic Acid / blood
  • Lipid Metabolism / drug effects*
  • Male
  • Muscle Contraction / drug effects*
  • Muscle Strength / drug effects
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / metabolism
  • Oxidation-Reduction
  • Oxygen Consumption / drug effects
  • Physical Endurance / drug effects*
  • Time Factors
  • Treatment Outcome
  • Up-Regulation
  • Young Adult


  • Blood Glucose
  • Ketones
  • Lactic Acid
  • 3-Hydroxybutyric Acid