You may have heard of the term "carbo loading". It has been determined that for endurance efforts, the carbohydrates you consume and store for several days prior to that effort are the principal source of energy during that effort. What is consumed a few hours before is not the main source for the required energy. In fact, eating too much before a hard rice impaires your effort by diverting blood flow to the digestive process. This is why Aunt Emily always insisted a wait of two hours before swimming. Read up on carbo-loading.
https://www.mayoclinic.org/healthy-l...g/art-20048518