You wouldn’t fill the fuel tank of an airplane with half the fuel needed to land it safely on the ground. You wouldn’t lift off in a spaceship that had a leak in it’s main propulsion rocket, and you certainly wouldn’t fill the gas tank of your car with chocolate pudding if you ever expected to successfully drive our of your parking lot. You need to fuel your body with the correct balance of carbs, fat and protein at a time prior to your race event that benefits your performance without leading you to some destiny with the glycogen wall.