Supplementary Ketones and Athletic Performance: What Does the Research Say?
Do keto supplements improve athletic performance?
In recent years, supplementary ketones have generated a lot of buzz in the athletic world. But what exactly are they? Do you need them? And can they actually enhance your performance? Let’s dive in and find out!
Ketones vs. Supplementary Ketones: What’s the Difference?
Photo: by Total Shape for Unsplash
What Are Ketones?
Ketones are compounds naturally produced by the body when carbohydrate availability is low—like during fasting or following a high-fat, low-carb diet. In these situations, the body shifts from burning carbs to burning fat for fuel, producing ketones in the process (1).
What Are Supplementary Ketones?
Also called exogenous ketones, these are synthetic ketones consumed through supplements to raise blood ketone levels—without the need to follow a strict ketogenic diet (1).
Types of Supplementary Ketones
Using ketones as a fuel source.
There are two main forms:
Ketone Salts: Contain beta-hydroxybutyrate (BHB) paired with minerals like sodium or magnesium. Usually sold as a powder mixed with liquids, they’re widely available.
Ketone Esters: A combination of a ketone body and an ester, found in liquid form. Harder to find, but they raise blood ketone levels more effectively than salts.
Most research has focused on ketone esters due to their potent effects on ketone levels (1, 2).
Why Consider Supplementary Ketones?
Achieving ketosis through diet can be tough and often comes with side effects like fatigue and nausea (a.k.a. the “keto flu”). Supplementary ketones offer a shortcut—boosting ketone levels within minutes, without cutting carbs or calories. The effects last a few hours, depending on the dose and type (3).
For endurance athletes, this can be a game-changer, since high-fat, low-carb diets may hinder performance. Supplementary ketones offer potential benefits without requiring dietary overhaul (2).
How Might Supplementary Ketones Help?
Spare Carbohydrates: They provide an alternate fuel source, helping preserve stored muscle carbs for later in performance (1).
Protect Muscle: High ketone levels may reduce muscle protein breakdown, helping maintain lean mass during intense training or low energy availability (2).
Performance Effects: What Does the Research Say?
Triathletes and cyclists experiment with using ketones for recovery.
High-Intensity Exercise
Research is limited, but current studies show no clear benefit for short, high-intensity efforts like sprint cycling.
In fact, a 2022 study out of McMaster University in Hamilton found that ketone supplementation reduced performance by ~2% when taken before a 20-minute cycling time trial (5).
Endurance Exercise
Here, the research is mixed. Some studies show improved endurance performance (especially in workouts under 2 hours) and increased fat burning—even when carbohydrate stores are adequate. Others report no improvement—or even decreased performance.
In 2016, a University of Oxford research group found that after 1 hour of consuming 500 mg·kg− 1 ketone esters, ketone levels were increased within the body to the desired range of 3 mmol·L− 1, the range linked with ketosis. There was increased fat usage for fuel even with high carbohydrate intake and stores in the body. Physical activity lasting less than 2 hours also increased endurance exercise performance (4).
In contrast, a 2022 review of research out of Dublin City University concluded that although there is a mechanistic bases for ketone supplementation to have the potential to improve athletic performance most studies have failed to produce positive performance results (3).
The takeaway? Results vary, and more research is needed, especially in ultra-endurance sports.
Overtraining and Recovery
Some studies suggest that ketone esters may help reduce the effects of overtraining and support faster recovery (2, 4).
In a randomized controlled trial involving 18 cyclists, researchers at KU Leuven in Belgium found that ketone supplementation helped blunt some of the negative effects of overreaching following endurance training—particularly muscle breakdown. Overreaching is a common strategy used by endurance athletes to stimulate fitness gains, but if not carefully managed, it can lead to performance declines (2).
Ketone supplementation may offer recovery benefits, particularly during periods of heavy training or stage racing. However, more research—especially in well-trained athletes—is needed to confirm these effects.
Side Effects and Safety
Supplementary ketones aren’t without downsides. Common side effects include:
Upset stomach
Cramping
Diarrhea
Nausea
Heartburn
They may also shift the body’s acid-base balance, making the blood more acidic. In rare cases, excessive acidity can lead to ketoacidosis, a serious medical condition.
To minimize side effects, avoid taking large doses (e.g., over 30 g) close to high-intensity activity (1, 3, 4).
Other Considerations
Timing and Context Matter: Effects vary based on whether you're fasting, fed, or exercising.
Cost: These supplements can be pricey—another factor to weigh before trying them (3).
Final Thoughts
While supplementary ketones are a hot topic, the evidence behind their performance benefits remains mixed. Some studies suggest potential perks for endurance and recovery, while others show no advantage—or even drawbacks.
What’s clear: they’re not a magic bullet. Focus first on a solid nutrition foundation—balanced meals, adequate energy, and consistent fueling. Always test new strategies in training, not on race day.
And before adding any supplement to your routine, talk to your Sports Dietitian to see if it's right for you.
Article written by: Neha Benwait, TMU student
Article edited by: Ashley Leone, RD; Grammarly; ChatGPT
Ready to take your performance to the next level with personalized sports nutrition? Book an appointment with Ashley, an expert Sports Dietitian who’s helped hundreds of athletes and active individuals fuel smarter and train stronger.
