Short answer
Ketone drinks taken before exercise did not improve performance. There was no difference across 13 trials, and in 2 trials performance fell by 2 to 7%. Performance only rose in 2 trials where people drank them after endurance training for 3 to 8 weeks.
Do ketone drinks boost exercise performance?
'Drink ketones → an extra fuel → better times' — does this formula hold?
Ketones are a fuel your body makes from fat when you fast or run low on carbs. Ads say drinking them gives your muscles an extra fuel and better times. We checked two cases: drinking them right before exercise, and drinking them during weeks of training.
Drinking them before exercise did not help
No difference across 13 trials
A 2020 analysis that pooled 13 trials found no difference in performance between people who drank ketones and those who did not. From short sprints to time trials of about 50 minutes, ester and salt forms gave the same result. A 2022 analysis of 8 trials (80 people) also found no difference in endurance performance.
Blood ketones clearly rose
But the extra fuel did not turn into better times
In every trial, blood ketones rose after the drink. But lactate, blood sugar, heart rate and how hard it felt showed no consistent change. In a trial of 12 people simulating a 3-hour bike race, average power in the final 15 minutes was 273 W versus 272 W, no difference.
Stomachs got upset and times got worse
2% slower in a 50-minute time trial
10 people who drank a ketone ester before a roughly 31 km time trial were 2% slower. Of the 11 who started, 1 kept vomiting and could not finish, and all 10 others had stomach discomfort. Another 10 people who took ketone salts produced about 7% less power in a high-intensity time trial.
Times only improved when taken after exercise for weeks
4% higher 30-minute power after 8 weeks
28 people drank 25 g of ketone ester right after exercise and before bed during 8 weeks of cycling training. Their 30-minute time trial power was 4% higher than with a same-calorie fake drink (302 W vs 291 W). In 18 people training twice a day for 3 weeks, the training load they could sustain in week 3 was 15% higher. Both trials came from the same research team.
Bottom line: one bottle before a race does not improve your time
The benefit showed up only when taken after training for weeks
Ketones taken before exercise did not improve performance across 13 trials and lowered it by 2 to 7% in 2 trials. Performance only rose in 2 trials where people drank them after endurance training for 3 to 8 weeks. A ketone drink right before a race does not make you faster.
A better body starts with a better question.PHYSIQUE NEWS