“One implication of this adaptation is protection from ‘hitting the wall,’ an event primarily associated with inadequate fuel for the brain. This problem (aka ‘bonking’) occurs in the non-keto-adapted athlete when muscle and liver glycogen reserves are exhausted, leaving muscle and brain to compete for the relatively small amount of glucose that can be made by gluconeogenesis from protein. In addition to improving fuel availability during prolonged exercise, the keto-adapted state may also protect against central fatigue.”
Jeff S. Volek and Stephen D. Phinney