Do Ketone Supplements Improve Athletic Performance?
Key takeaways
- Exogenous ketone supplements raise blood ketone levels, but this has not reliably translated into better endurance performance in controlled trials[1]
- A 2026 study in ketogenic-adapted athletes found no time trial benefit from adding 1,3-butanediol to a carbohydrate drink, despite significantly higher blood ketones[1]
- Carbohydrate before and during long exercise still has the strongest evidence for fueling performance
- Ketone products can cause stomach upset and are costly, so they are best treated as experimental rather than a proven tool
What are ketone supplements?
Ketone supplements are drinks or gels that raise the level of ketone bodies in your blood.
Ketone bodies are small molecules your liver makes when carbohydrate is scarce.
Your body normally makes them during fasting, intense exercise, or a ketogenic diet.
Ketone supplements let you raise ketone levels quickly, without weeks of carbohydrate restriction.
- Ketone esters, which are the most potent and studied form
- Ketone salts, often bound to sodium, calcium, or magnesium
- 1,3-butanediol, a compound the liver converts into a ketone body called beta-hydroxybutyrate (betaHB)
These products are popular with endurance athletes like cyclists and runners.
The pitch is simple. More ketones in the blood might mean more fuel for muscles and a longer-lasting energy supply.
Why would ketones help performance?
The theory rests on how your body chooses fuel during exercise.
Muscles can burn carbohydrate, fat, or ketone bodies for energy.
Carbohydrate stores in muscle, known as glycogen, are limited.
Once glycogen runs low, endurance performance tends to drop.
Ketone bodies are proposed as an extra fuel source that could spare glycogen and delay fatigue.
Ketones might also change how your body handles glucose and lactate during hard efforts.
This is why exogenous ketones caught the attention of endurance coaches and sports scientists over the last decade.
What does the research actually show?
Early studies on ketone esters produced some promising but inconsistent results.
More recent, well-controlled trials have been less encouraging.
A 2026 randomized trial tested 1,3-butanediol combined with carbohydrate in athletes already following a long-term ketogenic diet[1].
These athletes had followed a ketogenic diet for at least a year, so their bodies were already used to burning fat and ketones for fuel.
Researchers had them drink either plain carbohydrate or carbohydrate plus 1,3-butanediol before an hour of steady exercise and a 16.1 kilometer time trial.
Blood betaHB, the main ketone body, rose significantly in the group that got the ketone drink[1].
Despite that rise in ketones, time trial performance was not different between the two drinks[1].
Heart rate, perceived effort, lactate, and oxygen use during exercise also did not differ[1].
One notable change did show up. Blood glucose was lower late in the exercise bout with the ketone drink[1].
The study only included nine athletes, so it was likely underpowered to detect small effects[1].
The authors were careful to note that a lack of detectable benefit is not the same as proof of no benefit[1].
Taken together, current evidence does not support a reliable performance boost from exogenous ketones, even in athletes whose bodies are already adapted to using ketones for fuel[1].
Are there downsides or risks?
Ketone supplements often cause stomach upset.
- Nausea
- Bloating
- Diarrhea
- An unpleasant taste that some people find hard to finish
Ketone salts also add extra sodium or minerals, which matters if you are watching electrolyte intake.
The lower blood glucose seen with 1,3-butanediol in the recent trial is worth watching, since very low glucose during long exercise can itself hurt performance[1].
Ketone products are also expensive compared to standard sports nutrition like carbohydrate gels or sports drinks.
Long-term safety data in healthy athletes is still limited, since most trials only test single doses around a single workout.
What should athletes actually do?
For most endurance athletes, carbohydrate remains the best-supported fuel strategy.
- Eat a carbohydrate-rich meal 2 to 4 hours before a long training session or race
- Consume 30 to 60 g of carbohydrate per hour during events lasting over an hour, from sources like sports drinks, gels, or bananas
- Practice your fueling plan in training, not for the first time on race day
- Prioritize sleep and hydration, which have stronger evidence for supporting performance
- Talk to a sports dietitian before trying any new supplement, including exogenous ketones
If you are curious about ketone supplements, treat them as experimental rather than essential.
Test any new product in training well before an important event, since gut tolerance varies a lot between people.
Do not expect a ketone drink to replace basic carbohydrate fueling, since current evidence does not show it adds a meaningful edge on top of carbohydrate alone[1].
Who might these supplements help most?
Athletes already following a ketogenic diet were the focus of the most recent trial, since their bodies are theoretically primed to use extra ketones efficiently[1].
Even in this specific, ketone-adapted group, the added ketone drink did not outperform carbohydrate alone[1].
This suggests ketone supplements are unlikely to be a shortcut for athletes who eat a typical, higher-carbohydrate diet either.
People training for ultra-endurance events lasting many hours, where glycogen depletion is a bigger concern, remain the group most researchers think is worth studying further.
Recreational exercisers doing shorter workouts have little reason to consider these products at all.
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