Ketone supplements and endurance: worth the hype?

Ketone supplements have become very popular among health and fitness enthusiasts over the last decade, and in recent years, endurance athletes have begun experimenting with them to boost performance. But do they help you get to the finish line faster? Recent research out of McMaster University says no–in fact, they may even slow you down.

What are ketones?

The word “ketone” started popping up in conversations among health and fitness enthusiasts thanks to the popularity of the ketogenic diet. Your body produces ketones naturally, and these compounds can serve as a fuel source for your brain and muscles. When you follow the ketogenic diet, which requires you to eat little to no carbohydrates and a higher amount of fat, your body will crank up the production of ketones to use for energy, eventually putting your body into a state of ketosis.

These naturally-produced ketones are called endogenous ketones. Ketone supplements, also called exogenous ketones (because they’re from an external source), speed up the process of reaching ketosis without the restrictive diet.

Some endurance athletes, including runners, have begun taking ketone supplements as an alternative fuel source during exercise and to boost endurance performance by altering the way their bodies use other fuel sources like carbohydrates and fats. Martin Gibala, supervising author of the study, says their findings suggest that it doesn’t quite work that way.

The study

The researchers at McMaster University recruited 23 well-trained cyclists who cycled for at least five hours per week. They chose these participants because they had relatively consistent day-to-day athletic performance. 

Each participant completed two 20-minute time trials, one in which they were given a drink containing a ketone supplement, and one in which they were given a placebo (neither the participants nor the researchers knew at the time of the trials which drink the cyclists were receiving).

The results of the trials showed that the participants performed better with the placebo. In each case, the speed that the cyclists could sustain during the test was lower after drinking the ketone supplement. The researchers noted that these findings were in line with their previous research, which showed that ketone supplements increased cardiorespiratory stress during exercise.

The takeaways

The authors of the study are conducting more tests to better understand how ketone supplements influence exercise performance, but for now, it’s safe to say that ketone supplements are not helpful for endurance athletes, like runners and cyclists. 

If you’re looking for ways to leverage nutrition to improve performance, your best bet is to focus on eating whole foods and eating high-quality carbohydrates. Simple, fast carbohydrates are beneficial before and during a hard or long run, and good-quality protein will help your muscles repair after a tough training session. If you’re looking for more ways to maximize performance through nutrition, we suggest speaking with a dietitian, who can assess your current eating habits and help you find opportunities to improve your diet.