Ketone bodies can enhance athletic performance


Increasing athletic performance is a common goal among athletes, especially elite athletes.  The use of glucose for energy through carbohydrate loading has long been a means of supplying energy during workouts as well as during competitions.  One problem with using only glucose for energy needs is that there needs to be a constant supply of it.  Ketone bodies are an alternative energy source that can be considered for energy requirements and athletic performance. Scholarly articles, including original studies and literature reviews, were investigated to determine if, in fact, ketone bodies could increase athletic performance in athletes.  In addition to athletic performance improvements, ketone bodies were found to decrease adipose tissue and increase mental focus while decreasing mental fatigue during exercise.  Safety is a top concern as well as decreasing the potential for side effects. Minimal adverse effects have been found to occur.  While the use of exogenous ketones can increase the likelihood of adverse effects, this can easily be mitigated by decreasing the ketone body supplementation.  Studies conclude that the use of ketone bodies either through the safe implementation of the ketogenic diet or through ketone body supplementation can have positive effects on body composition as well as athletic performance while minimizing the potential for adverse side effects.

Ketone bodies can enhance athletic performance

How to fuel properly has long been a question for endurance and elite athletes.  It is desirable to be able to delay fatigue and have adequate energy for performance.  The traditional way to fuel the body and muscles for training and prior to competitions is through the use of carbohydrates or a carbohydrate loading diet.  By increasing the amount of glycogen stored in the muscles, it is thought that performance will thereby be increased due to readily available energy on demand (“Nutrition and Healthy Eating”, 2021).  After about 90 minutes of exercise, the body may run out of glycogen stores. Carbohydrates still must be consumed during exercise to keep a continuous supply.  Now, there is a different fuel that the body can utilize outside of glycogen and that is ketone bodies.  Ketone bodies are a lipid derived energy source produced in the liver (Pinckaers, Churchward-Venne, Bailey & van Loon, 2017).  They can be readily used and spare endogenous glycogen stores.  Given that glycogen stores are limited and are only a single source of energy, there may be other fuel sources that can prolong activity and enhance performance without depleting glycogen stores.

The purpose of this paper is to investigate the use of ketone bodies (both endogenous and exogenous) as a primary fuel source during endurance athletic activity. There are multiple ways that ketone bodies can be utilized. The focus of this paper will be an evaluation of studies and reviews that look at ketone use either from an endogenous source (ketosis) or an exogenous source (supplementation).

Ketone bodies can enhance athletic performance safely, especially for endurance athletes.  As noted, ketone bodies can be utilized from a state of ketosis through the ketogenic diet or through supplementation.  Positive body composition changes as well as performance improvements can be seen through the utilization of ketone bodies.  There are minimal side effects that can occur.  These side effects are not a given and can certainly be mitigated.  Ketone bodies should be considered when it comes to athletic performance.



            This literature review used only reputable, scientific databases.  Only peer reviewed articles, studies and literature reviews were evaluated for inclusion.  Google Scholar, PubMed and Alternative HealthWatch Database were searched for articles. The search strings used for the primary search were “Ketosis AND Athlete”, “Ketones AND Athlete” and “Ketogenic AND Athlete”.  No exclusion strings were needed.    

            Priority was given to quality articles that were published within the last 5 years. Original studies were prioritized, but literature reviews were included as well. Articles and studies revolved around either utilizing the ketogenic diet to produce ketone bodies or by supplementing with exogenous ketones.  Both are evaluated for their effectiveness.


Endogenous ketones

Cipryan, Plews, Ferretti, Maffetone & Laursen (2018) performed a study to determine the effects of a very low carbohydrate high fat diet (VLCHF, resulting in ketosis) over a 4 week period on physiological responses and performance during HIIT workouts.  18 trained men were split into two groups.  One group was the VLCHF group while another continued their Western diet.  Changes in time to exhaustion, VO2 max, VO2, and heart rate were trivial between the groups.  The VLCFH group had more signification changes in maximal fat oxidation rate.  The VLCHF group had a decrease in respiratory exchange ratio.  No adverse effects were found with respect to any aspect of athletic performance.

Kephart et al. (2018) performed a study that investigated the effects of a ketogenic diet (resulting in ketosis) on many factors, one of which was the athletic performance of CrossFit athletes. 12 participants were split into the study group and control group.   The study group ate a ketogenic diet and the control group ate their normal diet.  All participants continued their CrossFit exercise routines.  The performance measurements were for the one rep max back squat and 400 meter run. While there were significant positive changes in body adiposity, the performance change for recreational athletes was not significant.

Vargas et al. (2018) performed a study that investigates whether a ketogenic diet resulted in muscle loss. The study involved 24 men who participated in an 8 week resistance program.  There was the ketogenic diet group and the control group. There was a signification reduction in visceral adipose tissue (p < 0.05) and a signification reduction in fat mass (p < 0.5).  The ketogenic diet group showed no increase in body weight (p > 0.05) or muscle mass (p > 0.05).  The control group, however, did show increases in both (p < 0.05).  The control group showed no changes in total body weight or lean body mass (p > 0.05).  The result is that the ketogenic diet could be a useful dietary program to decrease fat while not decreasing lean body mass.

Exogenous ketones

Cox et al. (2016) reported on a series of studies that investigated the biochemical advantages as well as other effects of ketosis in humans.  There were 39 athletes that participated in the series of studies.    Exercise and resting metabolism were considered.  Ketosis in the participants was achieved by ketone consumption rather than endogenous ketone production.  No carbohydrate restriction took place.  The result was that the state of nutritional ketosis was shown to alter oxidation, energy transduction and substrate signaling.  In essence, nutritional ketosis and glucose have comparable physiological function, yet ketosis improved oxidative energy transduction.

Ma & Suzuki (2019) performed a literature review that summarizes recent research related to the use of ketone bodies and performance athletes.  Several key conclusions were discussed.  Elite athletes who were keto adapted had elevated IL-6 which meant the potential for performance enhancement.  This came with a warning, however, that this may cause side effects due to the inflammatory cytokines.  It was also noted that a ketogenic diet can increase fatigue.  One concern was whether a ketogenic diet would introduce muscle loss but that was shown not to be the case in a study of gymnasts. The results are positive, but do note that further studies are required to investigate further the potential for oxidative stress and muscle loss.

Pinckaers, Churchward-Venne, Bailey & van Loon (2017) performed a review of publications investigating the use of ketone body supplements to enhance athletic performance.  Ingesting ketone body supplements has been shown to rapidly increase the circulation of ketone body availability.  Whereas with the ketogenic diet, it can take much longer, even days, to get to a particular level of circulating ketone bodies.  Ketone esters can rapidly increase blood ketone bodies.  Ketone esters are absorbed through the gut and liver metabolism takes place to product ketone bodies.  Baseline nutritional status still plays an important role, however, and cannot be ignored.  A less than optimal effect can take place when ingesting ketone supplements along with high carbohydrate meals.  When it comes to athletic performance, ketone body metabolism is influenced by skeletal muscle fiber type, training status, circulating ketone body concentrations, and tissue type.  An interesting note is that if hyperketonemia is achieved through starvation, ketone body uptake diminishes around 3-4 mmol/L. Yet, after 2 hours of exercise, ketone body uptake was stimulated when hyperketonemia was achieved by exogenous ketones.  Given that ketones are an alternative fuel source for the brain, ketone bodies can also increase athletic performance by increasing cognitive abilities and decreasing (brain) fatigue. It also allows for the sparing of endogenous carbohydrate stores.

Poffé, Ramaekers, Bogaerts & Hespel (2020) performed a randomized crossover design with 12 highly trained cyclists.  They were split into two groups and performed a simulated race. All participants received 60g carbohydrates and either ketone ester boluses or a control drink. Net muscle glycogen breakdown, mean power output, and time to exhaustion were all similar between the groups. The conclusion was that the ketone bodies did not impact performance. 

Ketone bodies in general

Evans, Cogan & Egan (2017) performed a literature review that studied the effects of ketone bodies in exercise, both before and after, while focusing on potential benefits of ketone supplementation in performance and recovery for athletes. It is noted that skeletal muscles have the ability to resynthesize ATP from sources such as lactate, protein and ketone bodies. The metabolism of ketone bodies during athletic performance will vary greatly depending on training status, metabolic status and exercise intensity.  Highly trained athletes may have a greater ability to utilize ketone bodies in skeletal muscle. It was shown that due to the dramatic effect on skeletal muscle metabolism that ketone bodies have, the benefit to elite athletes is great.  Whether nutritional ketosis is achieved by endogenous means (ketogenic diet) or by exogenous means (supplementation), the result is statistically equal.  They also noted that ketone supplementation can come with side effects.  The most common side effects were flatulence, nausea, and diarrhea. 


            Ketone bodies can be a safe and effective fuel source for athletic performance.  They are a readily available and usable source of energy for the body.  Ketone bodies can be used in the form of supplements or they can be created in the body in a state of ketosis.  Ketosis is most often achieved through a ketogenic diet.

Performance benefits

            Whether or not ketone bodies can improve athletic performance or not is a key area of interest and study.  Additionally, what aspects of performance can be improved is also noteworthy.  Through the ketogenic diet, Cipryan, Plews, Ferretti, Maffetone & Laursen (2018) were able to show that a decrease in the respiratory exchange ratio and significant changes in maximal fat oxidation rates can be achieved. Now, with the use of exogenous ketones, Cox et al. (2016) showed that ketosis improved oxidative energy transduction.  The focus on athletic performance is often narrowed to the physical aspects.  But sometimes just as important can be the mental aspects such as focus.  It is known that ketones can be fuel for the brain.  Pinckaers, Churchward-Venne, Bailey & van Loon (2017) reinforced that cognitive ability could be enhanced through ketones as well as achieving a reduction in brain fatigue.  Both of these are valuable to performance.   

            Poffé, Ramaekers, Bogaerts & Hespel (2020) and Kephart et al. (2018) both came to similar conclusions.  While no negative consequences were shown, positive outcomes were also lacking.  Neither group was able to show any positive performance outcomes with the use of exogenous ketones.  Now, body adiposity was greatly improved, as shown by Kephart et al. (2018), but when it came to performance, nothing was noteworthy.

Body composition

            Body composition can be an important factor in athletic performance.   It has been shown that cardiorespiratory endurance can be increased as well as an increase in speed and agility in athletes by reducing non essential body fat (“Sports performance and body composition”, 2017).  As just noted, Kephart et al. (2018) clearly showed that body composition was positively affected when athletes achieved ketosis through the use of the ketogenic diet.  Vargas et al. (2018) noted similar findings.  A significant reduction in adipose tissue was seen as well as a great reduction in fat mass. 

Adverse effects

            Adverse effects are important to be aware of when it comes to any supplementation or change in dietary fueling habits when it comes to athletic performance.  While there are adverse side effects noted for exogenous ketones, they are mentioned relatively sparsely in literature. Namely, flatulence, nausea and diarrhea that are noted by Evans, Cogan & Egan (2017) are the most common.  If ketone bodies are desired for fueling purposes but side effects are a deterrent, one can consider the ketogenic diet which will supply endogenous ketones instead of requiring exogenous supplementation.

            Another big concern of using a ketogenic diet to produce ketones for fuel is the potential loss of muscle mass.  For athletes, this is incredibly important that their fuel source and eating lifestyle do not decrease their muscle mass.  While Kephart et al. (2018) and Vargas et al. (2018) demonstrated that there could be significant loss in adipose tissue, Vargas et al. (2018) also demonstrated that there was no loss in muscle mass.  There was no positive change in muscle mass either, whereas the control group did experience a positive change in muscle mass.  If an athlete is looking to gain body and/or muscle mass, a ketogenic diet specifically formulated for athletes would be appropriate to investigate instead of a standard ketogenic diet.

            It is also important to ensure that loss of athletic performance is not occurring when it comes to fueling options.  Cipryan, Plews, Ferretti, Maffetone & Laursen (2018) clearly noted that there was no decrease in athletic performance in their study.   While Kephart et al. (2018) didn’t observe any performance degradation, they also didn’t note any performance improvements for the recreational athlete.


Ketone bodies appear to be a great source of energy for endurance and elite athletes. 

While higher consumption of exogenous ketones may have adverse effects, the benefits appear to far outweigh the potential minimal side effects.  Ketone bodies are a safe and effective energy source that can be utilized by endogenous production or exogenous consumption.  Further studies should be done to analyze dosage of exogenous ketones and energy needs, as well as a detailed comparison of endogenous vs exogenous ketone body utilization.  Additionally, further studies regarding the effectiveness of ketone bodies both in the presence of and in the absence of available (and plentiful) glycogen. 


             Ketone bodies are a safe and effective fuel source. It is a good option to consider during endurance training.  There is much misunderstanding revolving around the difference between the presence of ketones due to exogenous consumption, nutritional ketosis and diabetic ketoacidosis.  Educational programs and awareness among the elite athlete community would be beneficial.


Cipryan, L., Plews, D. J., Ferretti, A., Maffetone, P. B., & Laursen, P. B. (2018). Effects of a 4-Week Very Low-Carbohydrate Diet on High-Intensity Interval Training Responses. Journal of sports science & medicine17(2), 259–268.

Cox, P. J., Kirk, T., Ashmore, T., Willerton, K., Evans, R., Smith, A., Murray, A. J., Stubbs, B., West, J., McLure, S. W., King, M. T., Dodd, M. S., Holloway, C., Neubauer, S., Drawer, S., Veech, R. L., Griffin, J. L., & Clarke, K. (2016). Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes. Cell metabolism24(2), 256–268.

Evans, M., Cogan, K. E., & Egan, B. (2017). Metabolism of ketone bodies during exercise and training: physiological basis for exogenous supplementation. The Journal of physiology595(9), 2857–2871.

Kephart, W. C., Pledge, C. D., Roberson, P. A., Mumford, P. W., Romero, M. A., Mobley, C. B., Martin, J. S., Young, K. C., Lowery, R. P., Wilson, J. M., Huggins, K. W., & Roberts, M. D. (2018). The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study. Sports (Basel, Switzerland)6(1), 1.

Ma, S., & Suzuki, K. (2019). Keto-Adaptation and Endurance Exercise Capacity, Fatigue Recovery, and Exercise-Induced Muscle and Organ Damage Prevention: A Narrative Review. Sports (Basel, Switzerland)7(2), 40.

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Pinckaers, P. J., Churchward-Venne, T. A., Bailey, D., & van Loon, L. J. (2017). Ketone Bodies and Exercise Performance: The Next Magic Bullet or Merely Hype?. Sports medicine (Auckland, N.Z.)47(3), 383–391.

Poffé, C., Ramaekers, M., Bogaerts, S., & Hespel, P. (2020). Exogenous ketosis impacts neither performance nor muscle glycogen breakdown in prolonged endurance exercise. Journal of applied physiology (Bethesda, Md. : 1985)128(6), 1643–1653.

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Vargas, S., Romance, R., Petro, J. L., Bonilla, D. A., Galancho, I., Espinar, S., Kreider, R. B., & Benítez-Porres, J. (2018). Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. Journal of the International Society of Sports Nutrition15(1), 31.

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