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The Tour race leader was asked about ketones, a supplement used as a recovery and weight-loss product, and Roglič wondered how effective they are. Ketones are not banned by the World Anti-Doping Agency, but there is some belief that they can add a performance boost to cyclists and other endurance athletes.
“Yeah, we are still using it,” Roglič said. “For the real effects, it’s really hard to say. It’s hard to feel it.”
Roglič is fielding more questions from media following the dominant performances by himself and his Jumbo-Visma team so far through this Tour. The team has won three stages and Roglič has finished second in three others. Roglič now holds a promising 59-second lead to his second-place rival with four stages to race.
Last year, the Dutch newspaper De Telegraaf revealed the team was using ketones, a dietary supplement that comes in drink form that is gaining popularity among endurance athletes. Other reports have suggested that the dietary supplements are being used by other teams in the peloton.
“If you ask all the guys now, going today on the Tour, they’re all tired,” Roglič said Wednesday after expanding his lead. “On the other hand, we just want to do the best that’s possible, in all aspects. Everything is just working towards that.”
Ketones are chemicals that are naturally produced within the liver during the metabolism of fat, and their production occurs when the body is running low on carbohydrates for fuel. The use of synthetic ketone supplements is believed to coax the body to burn fat storage instead of muscle, which prevents muscle breakdown throughout a long-distance endurance event.
Ketone supplements such as ketone salts or ketone esters, as well as the low-carb ketogenic diet, are widely marketed for weight loss. The use of exogenous ketone supplements is believed to mimic what happens when individuals go on a ketogenic diet (in which an individual limits carbohydrates intake). Increased level of ketones in the blood is believed to transition the body to burn fat as a fuel source.
How effective they are for endurance athletes is still open for debate. Earlier this year USADA chief Travis Tygart criticized UK Sport for performing ketone trials on its athletes in the lead up to the 2012 Olympics. In 2019 UCI president David Lappartient said the governing body was monitoring the use of ketones in cycling.
Roglic, who has been questioned by journalists about his credibility, said earlier this week fans and media should believe his performances.
“They do a lot of doping controls and even [Sunday] at 6 a.m. I did a control so there is nothing to hide,” Roglic said Sunday “Looking from my side, you can definitely trust it.”