UCI Medical Director Xavier Bigard said there is no scientific evidence that ketones improve performance.

In an interview with L'Équipe (open in new tab), he also admitted that adding ketones to the list of banned substances is "complicated."

At the World Championships in September, the UCI announced that it had ordered a scientific investigation into the effects of ketones and recommended that athletes refrain from using them during that time.

Teams signing the additional voluntary measures of the Movement for Reliable Cycling (MPCC) have already agreed not to use ketones, and riders such as Romain Bardet and Guillaume Martin have recently called for a ban on ketone use throughout the peloton. Some World Tour teams, such as Dečuninck Quickstep and Jumbo Visma, have agreed to the use of ketones. [To date, there is no scientific evidence that ketones improve performance," Bigard told L'Équipe. 'There have been five studies and just as many papers published. The first study is from 2016 and is misleading. It mentioned an improvement of about 15%, but that was done under overtraining conditions, which doesn't quite match the reality of racing and training.

"None of the next four studies conducted confirmed these results. In fact, the researchers at the University of Leuven who conducted the first study published a second study in 2020 that found no improvement in performance under normal conditions. Another study even showed that under certain conditions it worsened."

Bigard, who has held the position since June 2018, cited possible digestive side effects when asked why the UCI does not currently recommend the use of ketones in the peloton.

"The risk of these side effects is limited, but present. And unless we see an improvement in performance because of this potential side effect, I don't see why we should recommend its use." Therefore, we have issued a notice of deprecation."

In order for a substance to be added to WADA's prohibited list, it must meet two of the three criteria. Namely, the substance must "enhance or have the potential to enhance sporting performance," "present an actual or potential health risk to the athlete," and be "contrary to the spirit of the sport." Biggard noted that the UCI study on ketones has only just been commissioned, but that current evidence makes it difficult to envision an outright ban on the substance.

"Frankly, given the current state of our knowledge, it seems complicated," he said. But because we are listening to feedback, we have commissioned a scientific study and are currently finalizing the terms of reference before putting out a call for proposals later in the year."

"There is good reason to believe that ketones do not enhance performance, but there are one or two things that need to be addressed: intake, that is, the amount you take and the repetition of intake, and the type of ketone. There are probably some categories that have not been adequately studied, and that is what we will look into."

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Asked why some teams stick with ketones when they supposedly have no performance-enhancing properties, Bigard replied: "It remains a mystery. There is some question as to whether it is a placebo effect."