Do Ketones Improve Running Performance?

Ketones for runners are a trendy new supplement – but do they actually work? In this article, I will dive into the research around ketones for endurance athletes. I’ll examine the pros and cons of ketones for performance and recovery, as well as the cost of different brands, so you can make an informed decision. 

One important note first: The research is presently limited on ketones for runners. Ketone companies do fund some of the studies, which lends some bias to the findings.

 We also do not have any long-term evidence on ketone supplements. As research evolves, we may learn more about negative effects of certain supplements or dietary practices. (For example, research initially showed potential benefits of low-carb, high-fat diets for endurance athletes. However, as more research was done, the data demonstrated that these diets did not improve performance and came with potential performance and health drawbacks.)

Additionally, most studies on ketones for endurance athletes are done on male athletes. Female athletes oxidize fat differently than male athletes, so we do not fully understand how ketones work for female runners. 

An overview of ketones for endurance athletes

Ketone supplements are exogenous ketones – created outside of the body. Our bodies also create endogenous ketones. 

Ketones are created in the liver during periods of energy deficiency or low-carbohydrate availability. Your body produces them during prolonged exercise (when blood sugar gets low) or by dietary interventions (ketogenic diets or low-carbohydrate/high-fat diets). 

Ketones can be used by the brain, skeletal muscles, and other essential organs when carbohydrates are unavailable. However, energy production from ketones is slow and inefficient. 

Exogenous ketone supplements are different than a ketogenic diet. While a ketogenic diet severely restricts carbohydrate and protein intake and prioritizes fat intake to cause ketone body production, ketone supplements provide ketones without dietary altercations (other than taking the supplement). 

If you want to learn more, I found this episode of Holley Fueled Nutrition’s podcast to be very helpful.

What does drinking ketones do during exercise? 

When you run, you burn a combination of fat and carbohydrates for energy. The faster you run, the more carbohydrates you burn for energy. Carbohydrates are broken down more efficiently into energy than carbohydrates, hence the body’s preference for glycolysis at higher intensities. 

Ketones for runners are not intended to put the body into a state of ketosis. Instead, ketone shots provide additional energy through a different metabolic pathway than glucose (carbohydrates). Theoretically, ketones could spare glycogen stores during long efforts such as marathons or ultra marathons. (However, the research on glycogen sparing is sparse.)

Ketone supplements are not intended to replace gels. Instead, ketone shots are designed to be used in addition to carbohydrates and fluids with electrolytes. 

However, there are risks and side effects associated with ketones that may cause them to worsen performance. Some research demonstrates that ketone supplementation leads to worse performance, especially at higher intensities (due to under-utilization of carbohydrates). 

A 2023 cross-over study in the International Journal of Sport Nutrition and Exercise Metabolism found that ketone supplementation impaired time trial performance in well-trained cyclists. The cyclists who ingested a ketone supplement 30-minutes before a time trial perfomed 2.4% worse than the placeo group. Additionally, the ketone group reported a statistically significant higher occurrence of gastrointestinal upset. 

Ketone supplementation may not improve running performance, despite the theories around glycogen sparing. A 2019 study in Medicine and Science in Sports found that ketone supplementation did not improve 10K running performance in trained runners. Similarly, another 2020 study found no differences in 5K performance when runners supplemented with ketones 60 minutes prior. 

There is currently little to no evidence on whether ketones can improve marathon or ultra marathon performance. 

The primary side effect of ketone supplementation is gastrointestinal upset. Gastrointestinal upset will impair performance, especially in a race setting. 

Related: How to Fuel Your Long Runs

Do ketone supplements improve recovery?

Some runners opt to take ketone shots after long runs and hard workouts. The theory is that post-run ketone supplementation promotes deeper and more rapid glycogen resynthesis when coupled with adequate carbohydrates. 

The idea that ketones promote recovery emerged after a 2019 randomized controlled trial in the Journal of Physiology. The researchers observed that trained male athletes who took post-exercise ketones showed fewer signs of overreaching during an intensive training block (two training sessions per day, for six days a week, for three weeks). 

Importantly, the researchers noted that the ketone-supplementing athletes sponateously ate more throughout the day than the placebo group. That’s a confounding variable, since we know that increased carbohydrate and protein intake improves recovery. 

Ketone supplements won’t replace carbohydrate replenishment after runs. If you take ketones after a run but don’t eat enough carbohydrates, you won’t experience any benefit. 

Related: A Thorough Guide to Run Recovery Nutrition

Are ketone supplements safe?

Ketone supplements are safe in the short-term. However, whether ketone supplements are safe in the long-term is unknown. As summarized in a 2023 article in Nutrients, it is unknown whether long-term ketone supplementation could help or harm skeletal muscle metabolism. 

With any supplement, there is an inherent risk that the supplement contains ingredients other than the label states. Supplement contamination is also a concern. Since the FDA does not regulate sport supplements, you want to pick third-party tested supplements to ensure safety, purity, and efficacy. 

What are the drawbacks?

Beyond the GI upset and potential performance impairments, ketone supplements have two major drawbacks: they are expensive, and they taste bad. 

As of 2024, Ketone IQ costs $60 USD for 12 servings ($5.00/serving). Delta G ketones cost $30 per bottle. 

Let’s take a moment to do a bit of a financial analysis. If you wanted to use ketones as a recovery supplement over a 16-week marathon training block. You plan on taking them only after your two hard workouts and long run (three times per week). You will need 32 bottles of Ketone IQ – a cost of $240. 

For $240, you could also buy a pair of carbon plated shoes or sixty-one Maurten gels. Either of these investments will yield more significant performance improvements. 

Ultimately, you have to weigh the drawbacks (including cost) with the potential benefits of ketones when deciding if you should supplement them. 

Top brands selling ketones for runners

If you are going to use ketone supplements, you want to pick a safe and effective brand. 

I am not endorsing these products; instead, I am taking an objective look at the pricing, safety, and claims of available products at the Feed.

Ketone IQ 

• Brand side effects: GI upset including nausea, vomiting, cramping, and diarrhea
• How much is Ketone IQ? $5 per shot, in either a bottle or gel pouch
• Third-party tested? Ketone IQ is NSF Certified for Sport and WADA compliant

Delta G Esters

• Brand side effects: GI upset including cramping, diaherrhea, vomiting and nausea
• How much is Delta G? $85 for 3 bottles
• Third-party tested? WADA-compliant but is not certified safe for sport

Kenetik Ketone Concentrate

• Brand side effects: GI upset, including cramping, nausea, vomiting, and diarrhea
• How much is Kenetik?: $20 for 4-serving bottle ($5/serving)
• Third-party tested? No

The TL;DR on ketones for runners

Ketones for runners are an expensive supplement, with limited evidence around the performance benefits. Many studies show no improvement in actual running performance for shorter distances, and the research is lacking for longer distances. 

Some research indicates that ketones may enhance recovery during intense training periods. However, you cannot use ketones to replace smart recovery nutrition. If you do opt to use ketone supplements, you are better off using them as a recovery supplement, not before a run.

Ketones are expensive and unpleasant-tasting. The long-term impacts on health and performance are not understood. If you choose to supplement, choose third-party tested brands. 

Otherwise, you will get a lot more benefits from smart training, appropriate nutrition, and these research-backed supplements:

• Running gels
• Creatine
• Caffeine
• Iron 
• Salt tablets

Caveat: I am a running coach with my master’s degree in Applied Exercise Physiology and several years of coaching experience. This article provides evidence-based yet general advice on ketones for runners. However, you should always consult a medical professional or registered dietitian about any supplements or dietary changes.