Benefits
Raises blood ketone (BHB) levels within one to two hours
In healthy adults, single drinks of 140 to 714 mg/kg raised blood BHB to a peak within 1 to 2 hours, reaching 3.3 mmol/L at the top dose, with levels back to baseline within 3 to 4 hours. At a similar BHB dose, the ester gave a peak almost three times that of ketone salts (2.8 vs 1.0 mmol/L), and a meal beforehand lowered the peak by a third. A higher reading is a change in blood chemistry, not a benefit in itself.
Endurance time-trial performance in trained athletes
In 8 endurance athletes tested after an overnight fast, the ester plus carbohydrate added about 2% (411 m) to the distance covered in a 30-minute cycling time trial versus carbohydrate alone. Later trials did not repeat this: no change in a 10 km run (8 runners), a team-sport shuttle run (11 athletes) or a simulated cycling race (12 cyclists), and 2.4% lower power in a 20-minute time trial (23 cyclists).
Endurance training adaptations with intake after exercise
Two trials from one Belgian research group gave 25 g after training and before sleep. In 3 weeks of overload training (18 fit men), sustainable training load and late-session power were 15% higher than with a control drink. Over 8 weeks of cycling training (28 trained men), 30-minute time-trial power ended 4% higher and peak oxygen uptake rose 12% versus 6%. Both trials enrolled men only.
Lower blood glucose response after a glucose drink
In 20 healthy young adults, a ketone ester drink 30 minutes before a 75 g glucose drink cut the glucose area under the curve by 17% versus water, without raising insulin secretion. Taken before each meal for 14 days, it lowered glucose after meals by about 8% in 14 adults with obesity but did not improve glucose control in 15 adults with type 2 diabetes, and 28 days of use left fasting glucose unchanged in healthy adults.
Hunger and the appetite hormone ghrelin after a single drink
In 15 normal-weight adults, a ketone ester drink raised BHB to 3.3 mmol/L and, compared with a dextrose drink of equal calories, lowered ghrelin 2 to 4 hours later and lowered hunger and desire to eat at 1.5 hours. The fullness hormones GLP-1 and PYY were also lower. The study tracked ratings and hormones for a few hours, not food intake or body weight.
Thinking speed and accuracy during fatigue or low oxygen
In 11 team-sport athletes, errors on a multitasking test rose after exhausting shuttle running with carbohydrate alone but not with the ester added. In 16 military personnel breathing low-oxygen air at rest, the ester gave 6.8 more correct responses per minute on a coding task and a smaller fall in blood oxygen. In 8 runners, reaction time and multitasking did not change after a 10 km run.
Mechanism of action
Split into BHB and (R)-1,3-butanediol, which the liver turns into BHB
Esterases in the gut, blood and liver are expected to split the ester into D-BHB and (R)-1,3-butanediol, and the liver converts the butanediol to BHB and acetoacetate using alcohol and aldehyde dehydrogenase. The intact ester was not detected in blood after drinking it. The BHB supplied is the D form the body makes itself, whereas ketone salts can be about half the L form.
Adds a short-lived acid load the body offsets by breathing harder
Blood pH and bicarbonate fall for a few hours after a drink. In healthy adults, pH fell from 7.41 to 7.31 and bicarbonate from 23.6 to 17.0 mmol/L an hour after a drink, staying within the normal range; in a cycling race study pH dropped from about 7.42 to 7.36 and bicarbonate from 26.0 to 21.6 mmol/L. Those researchers suggested lower buffering capacity could matter in the hardest final part of a race.
Shifts muscle fuel use during exercise
In the first athlete studies, ketosis lowered blood lactate and muscle glycolysis and raised use of fat stored in muscle, even with carbohydrate on board. A later trial that provided a carbohydrate-rich meal and matched carbohydrate intake found no sparing of muscle glycogen during a 3-hour simulated race, so this fuel shift does not reliably appear.
Clinical trials
Five studies of fuel use in high-performance athletes; in the performance study, a randomized crossover after an overnight fast compared 573 mg/kg of the ester plus carbohydrate with an isocaloric carbohydrate drink before 1 hour of cycling at 75% of maximal power and a 30-minute distance time trial. Funded by DARPA and UK Sport; authors included inventors of the ester and TdeltaS employees. (Cox et al. 2016, Cell Metab)
39 high-performance athletes across five studies; 8 endurance athletes (6 men, 2 women) in the time-trial study.
Ketosis lowered muscle glycolysis and blood lactate and increased oxidation of fat stored in muscle. In the time trial, athletes cycled about 411 m (about 2%) further with the ester than with carbohydrate alone. The performance group was small and tested fasted, and later trials in fed athletes with matched carbohydrate have not reproduced the gain.
Double-blind randomized crossover: 573 mg/kg of ketone monoester with an 8% carbohydrate drink versus the carbohydrate drink alone, before 1 hour of running at about 65% of VO2max and a self-paced 10 km treadmill time trial. (Evans et al. 2019, Med Sci Sports Exerc)
8 endurance-trained runners.
Plasma BHB was about 1.0 to 1.3 mmol/L during exercise, but 10 km time did not differ (2,402 vs 2,422 seconds, P = 0.483). Running economy, heart rate, effort ratings, blood glucose and lactate, reaction time and multitasking were also unchanged.
Randomized crossover: three ketone ester doses (25, 20 and 20 g) or a control drink, with 60 g carbohydrate per hour, during 3 hours of intermittent cycling followed by a 15-minute time trial and a maximal sprint; funded by Research Fund Flanders. (Poffé et al. 2020, J Appl Physiol)
12 highly trained male cyclists.
Blood BHB rose to about 3 mmol/L in the first half of the race, while blood pH fell from about 7.42 to 7.36 and bicarbonate from 26.0 to 21.6 mmol/L. Muscle glycogen use did not differ, and 15-minute time-trial power (273 vs 272 W) and sprint time to exhaustion (59 vs 58 seconds) matched the control condition.
Randomized, triple-blind crossover sized for adequate statistical power: 0.35 g/kg of the ketone monoester or a flavor-matched placebo 30 minutes before a 15-minute warm-up and a 20-minute time trial. (McCarthy et al. 2023, Int J Sport Nutr Exerc Metab)
23 trained cyclists who rode more than 5 hours a week.
Pre-exercise BHB was 2.0 vs 0.2 mmol/L. Mean time-trial power was 2.4% lower after the ester than after placebo (255 vs 261 W, p < .01). The authors could not explain why performance was impaired.
Randomized controlled trial: 25 g of ketone ester after each of two daily training sessions and 30 minutes before sleep, versus an isocaloric control drink, for 3 weeks (6 days a week) of intensified endurance training; funded by Research Fund Flanders, with the ester bought from TdeltaS. (Poffé et al. 2019, J Physiol)
18 fit men (9 ketone ester, 9 control).
Sustainable training load in week 3 and power in the final 30 minutes of a 2-hour session were 15% higher with the ester. It blunted the rise in night-time adrenaline and noradrenaline and the fall in heart rate, and energy balance stayed near neutral (+198 kJ/day) instead of turning negative (-2,135 kJ/day). A small single-lab trial that drew several published comments in the journal.
Randomized trial: 25 g of the ketone monoester or an isocaloric placebo after exercise and before sleep during 8 weeks of supervised, periodized cycling training. (Robberechts et al. 2026, J Physiol)
28 trained men (14 per group).
After training, 30-minute time-trial power was 4% higher with the ester (302 vs 291 W). Relative peak oxygen uptake rose 12% versus 6%, and the muscle mitochondrial enzyme citrate synthase was 14% higher, while cardiac adaptations did not differ. Same research group as the 3-week overload trial; men only.
Randomized crossover with blinded participants and laboratory analysts: ketone monoester (deltaG, 0.45 mL/kg body weight) or water 30 minutes before a 75 g oral glucose tolerance test. (Myette-Côté et al. 2018, J Physiol)
20 healthy adults aged 18 to 35 (10 men, 10 women).
BHB rose to 3.2 mmol/L within 30 minutes. Versus water, the glucose area under the curve fell 17%, fatty acids fell 44%, and an oral insulin sensitivity index improved by about 11%, without higher insulin secretion. A single-dose study in healthy young adults.
Single-blind randomized crossover: 650 mg/kg of ketone monoester (split dose) or a taste-matched placebo before 20 minutes of breathing 9.7% oxygen (equal to 6,096 m altitude) at rest; funded by US Special Operations Command through a contract awarded to HVMN Inc. (McClure et al. 2024, Exp Physiol)
16 male military personnel.
BHB exceeded 4 mmol/L and blood glucose was about 20 mg/dL lower than with placebo. During low oxygen, the ester condition gave 6.8 more correct responses per minute on a code-substitution task, and oxygen saturation fell less (76.8% vs 70.4%). One author held stock in HVMN and other ketone companies.