Your liver also stores a significant amount of glycogen that it can release into the bloodstream. "Bonking" is a term from endurance events, for example in a marathon bonking typically takes place around 20 miles into the race when runners have been running for more than 2 hours, which fully depletes their glycogen stores. Modern runners typically refuel with carbohydrates, drinks/gels, to delay bonking, but depending on pace and time you typically can't consume enough calories to fully replenish what you have used and will bonk eventually. Then you will need to continue at a slower pace burning fat for fuel.