Athletes' physical endurance can be enhanced by drinking ketones — biochemical fuel normally produced during starvation.

Fasting or prolonged exercise drives liver cells to make ketone bodies as a fast-acting fuel to help tissues cope with the energy deficit. To test the effect of these molecules on exercise metabolism, Pete Cox at the University of Oxford, UK, and his colleagues gave endurance athletes a drink containing ketones. They found that after a prolonged period of cycling, the metabolism of those who consumed ketones had shifted so that they conserved glucose and burned more fat than those who did not receive ketones. In a 30-minute time trial done after one hour of cycling, athletes who had consumed ketones and carbohydrates cycled more than 400 metres further, on average, than those who had eaten only carbohydrates.

Cell Metab. http://doi.org/bm8z (2016)