The Effects of Ketogenic Diets and Ketone Supplements on the Aerobic Performance of Endurance Runners: A Systematic Review.
Level 1 - systematic review of randomized trials
Systematic review of interventional trials
PubMed 39233399 · doi:10.1177/19417381241271547
What was done
A systematic review searched PubMed, Web of Science, ProQuest, and Science Direct through October 2023 for human studies evaluating the effects of ketogenic diets (>60% fat, <10% or <50 g carbohydrates/day) or ketone supplements (esters, salts, medium-chain triglycerides, or 1,3-butanediol) in adult endurance runners. Two independent reviewers screened studies. Primary outcomes were markers of aerobic performance, including VO2 max, race time, time to exhaustion, and rate of perceived exertion assessed via incremental exhaustion tests, time trials, 180-minute runs, or run-to-exhaustion protocols.
What was found
Twelve studies with a total of 132 endurance runners were included (5 on ketogenic diets, 7 on ketone supplements). The abstract does not report specific numerical values or effect sizes. None of the included studies reported benefits of ketogenic diets or ketone supplements on selected markers of aerobic performance compared with controls. Reductions in body weight and fat with preserved lean mass and improved glycemic control were reported in some ketogenic diet studies.
Why it matters
Despite popular interest in fat adaptation and exogenous ketone fueling for endurance athletes, current evidence shows no measurable performance benefits over standard control conditions.
Limits
The abstract provides no numerical data, confidence intervals, or meta-analytic pooling. The evidence base is small (132 participants across 12 trials), with substantial heterogeneity in study design and protocols, short intervention durations, and a lack of gender balance.
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- contradicts Beta-hydroxybutyrate has been shown to enhance physical endurance.