Limited research to date shows no clear performance benefit to endurance athletes following a ketogenic diet [1
]. Despite increased fat burning potential, endurance capacity in keto-adapted athletes still appears to be limited by glucose availability [2
]. A keto-adapted runner will simply have less glucose available to fuel a long run than a carbohydrate-fed competitor, and research to date suggests that this impairs speed and performance, even if carbohydrate is temporarily restored pre-run [3
Additionally, keto may hinder performance benefits due to the fact that ATP (energy) production from fatty acids requires more oxygen than glucose does [2
]. These greater oxygen demands decrease efficiency during exercise and thus limit the potential performance benefits for athletes following a strict ketogenic diet.