Ketones for Performance: Hype or Help?

If you listen to podcasts in the endurance sports and/or wellness space, you’ve likely heard ads for ketone products designed to give you an edge in sport and life. But this purported edge doesn’t come cheap (anywhere from $5 to $30 a serving depending on the brand), and some have asked, “Is it worth it?”

I first tried and wrote about ketones for Bicycling Magazine in 2016. The idea, as it was pitched to me, was that drinking a ketone ester-infused beverage could trick your body into staying in fat-burning mode longer, so you could spare your limited glycogen stores and push back the point of muscle burn and fatigue. 

On paper it makes sense. Ketones are produced from body fat to help keep us going when food is scarce. When you don’t have enough carbs, your liver converts fatty acids into ketone bodies, which can serve as an alternative fuel for the brain, heart, and skeletal muscle. If you take them as a supplement (i.e. ketone esters), you can get high levels of blood ketone bodies without restricting carbs, so ideally, you can improve performance and recovery by altering the body's fuel source and reducing the use of muscle glycogen. Early research looked promising, showing a small (~2%) improvement in time trial performance among those using ketone esters (the most potent form of ketone supplements). 

The next time I tried them was in 2022 after I heard a few influencers swear by them for cognitive performance, since your brain, which runs almost solely on glucose from carbs, can also burn ketones for energy. Again, it makes sense on paper. And there’s some evidence that they help, especially in those with mild cognitive impairment. 

My experience both times? Meh. For one, they taste terrible. I’ve never drunk nail polish remover, but it’s what I’d imagine it would taste like. I didn’t really notice any benefits on the bike. Off the bike, the main thing I noticed was a slight decrease in appetite, but I’m not sure that was a positive thing since I need to be properly fueled for training and racing, and the ketones didn’t seem to help with those things, at least for me.

I’m not alone in my underwhelm. Research to date has been mixed, largely unconvincing, and sometimes negative. One 2017 study found that ketone supplementation resulted in a slight impairment in performance in a 31K laboratory-based time trial and was associated with gut discomfort and higher perception of effort. Another paper from 2023 echoed those findings, finding that mean power output was 2.4% lower after cyclists ingested a ketone monoester supplement than when they drank a placebo. Other research has found no performance effect. 

Scientists are still working to understand all the factors that could impact performance with ketone use, including the type and dosage of ketones used and the intensity and duration of the exercise (i.e., maybe there’s a benefit in longer, lower intensity events). There’s also some evidence that they may facilitate recovery if used after exercise. 

When it comes to the cognitive benefits, there’s a bit of compelling research on female athletes. One study that looked at trained female cyclists and tested whether taking a ketone monoester plus carbohydrates would improve physical performance and brain function after exercise found no boost in physical performance with the ketone plus carb combo, but did find better cognitive performance post exercise, including 14% faster reaction times compared to carbs alone. What does that mean practically? It’s hard to say.

In the end, while there may be more concrete benefits research has yet to uncover, right now, the evidence just isn’t there, especially for everyday active and athletic women who would reap far more measurable benefits by dialing in their nutrition, getting good sleep, and hitting the basics of training and recovery. Until there’s more targeted research, ketones should be considered an expensive and optional experiment—not a staple.