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Why are Tour de France Riders Taking Ketone Supplements?

By Jiri Kaloc

After last year’s speculations, there was even more talk about ketone supplements at the 2019 Tour. A few teams outright confirmed using exogenous ketones as a part of their riders’ fuelling strategy and many more are suspected. So, what are these ketones everyone is talking about and why would the pros be interested in them?

What are ketones?

Ketones are produced by the liver from fats and they serve as an energy source in the body. This process mainly happens when carbs are not available in the body to be used for energy. This would happen when fasting, when on a carbohydrate-restricted diet like the ketogenic or low-carb diets or on a long ride without energy bars or fuel.

Ketone supplements, or exogenous ketones as they are also called, are produced by mixing ketones with alcohol to form ketone esters that athletes can drink. Such ketones are considered a dietary supplement so riders can use them just like vitamins. They are not on the prohibited list of the Tour de France or the UCI.

Ketone supplements are not on the prohibited list of the Tour de France or the UCI. © Profimedia, EPA

Who is using them?

Speculations of ketone use date back to the 2012 Olympic Games in London. The Tour was most talked about in this regard in 2018 when Geoff Woo, CEO of HVMN, a company producing ketone drinks, said that “seven teams will be drinking ketones as part of their nutrition strategy” at the Tour. But many teams that year denied it when asked and none confirmed. This year has been a different story. The Jumbo-Visma’s team manager Richard Plugge said that his riders were using ketones. Team Lotto Soudal also told in interviews they use them. And professor Peter Hespel who works closely with the Deceuninck-QuickStep team mentioned that ketone supplements are “probably a piece of the puzzle” of the Belgian team’s success.

What are the benefits?

The number of studies focusing on exogenous ketones has been growing in recent years. Based on the research so far, we can be quite confident that they are effective in increasing blood ketone levels. They can get athletes to a state of ketosis without the need for a ketogenic diet or fasting. When it comes to claims about various aspects of athletic performance, the strength of evidence overall is still low but the results are quite interesting.

Team Lotto Soudal is quite open about using ketones. © Profimedia, Zuma Press

Studies are showing that ketone esters consumed along with carbohydrates may improve glycogen re-synthesis and therefore enhance recovery. This would make the supplement very appealing especially in stage races like the Tour where recovery during the 21 days of racing is key. Studies consistently show improved performance in endurance tests but mixed results when it comes to time trials. Exogenous ketones also do not seem to improve sprint performance.

If new studies with larger sample sizes and more professional level athletes involved confirm these findings, we might see a lot more teams use them at the Tour. Ketones have the potential to become the norm rather than the exception at the Tour.