Acute Ingestion of Ketone Monoesters and Precursors Do Not Enhance Endurance Exercise Performance: A Systematic Review and Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 35042186 · doi:10.1123/ijsnem.2021-0280
What was done
Authors searched PubMed, SPORTDiscus, and CINAHL for randomized controlled trials evaluating the effects of acute ketone precursors or monoesters versus nutritive or nonnutritive controls on endurance exercise performance in humans. A random-effects meta-analysis was performed to calculate standardized mean differences using Hedges' g and 95% confidence intervals.
What was found
Eight studies comprising 80 participants (77 men and 3 women) were analyzed. Overall endurance performance showed no significant difference between ketone and control conditions (Hedges' g = 0.136; 95% CI [-0.195, 0.467]; p = .419). Subanalyses showed no significant effects on time to exhaustion (Hedges' g = -0.002; 95% CI [-0.312, 0.308]; p = .989) or time-trial performance (Hedges' g = 0.057; 95% CI [-0.282, 0.395]; p = .744). All studies observed elevated blood ketone levels post-ingestion, with monoesters increasing concentrations more than precursors.
Why it matters
Despite interest in ketone supplementation for metabolic alterations, pooled trial evidence shows that acute ingestion provides no measurable benefit for human endurance performance.
Limits
The total evidence base is small, consisting of only 8 studies and 80 participants. There is an extreme sex imbalance (96% male participants), and the findings are limited to acute ingestion rather than chronic supplementation or recovery protocols.
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