i sort of suspect the opposite--you might be able to stay fat adapted with the odd carb up--but the fat adapted state is also one that's sparing of carbs--that might be it's defining characteristic, since even a carb adapted person still gets much of their energy at least in the fasted state from fat. This is sort of the whole point when marathoners go low carb, hoping to fuel on fat, conserve glycogen, and avoid bonking.