Are Ketone supplements good or bad for athletic performance?

Many athletes are turning to ketone supplements to try and improve performance - but are they effective?

UBCO assistant professor Jonathon Little says a previous study found ketone supplements may improve endurance - but not necessarily high-intesity performance.

He says ketone levels rise naturally in the body when you haven't been consuming enough carbohydrates - and when there's less glucose, your body switches to ketones to burn fat.

"But for an athlete, or someone trying to do high intensity exercise, having a signal floating around in your blood that says 'turn off my ability to burn carbohydrates' is probably not a good thing. And that's essentially what we saw is that in this high-intensity performance taking the ketone supplement was actually detrimental or negative," he says.   

In his study, Little recruited ten healthy adult males with similar athletic abilities and body mass indices. After a period of fasting, they were asked to consume either beta-hydroxybutyrate ketone salts or a flavour-matched placebo, in a randomized order, and then engage in a cycling time trial. Power output on the day participants consumed ketone salts was seven per cent lower than on the day when they consumed the placebo.

Little says ketone supplements are also used to diet - but what's not known are the long-term effects of tricking the body into thinking it's starving.