What to eat during competitions

One of the mainstay of my tournament preparation has to be what I eat and when. Having that delicious brunch 1 hour before condemned my match for certain. Lately, I have been eating pretty lean meals as a result of that bout with GI health imbalance. The doctor recommended the BRAT (banana, rice, apple sauce, toast) diet to help me through it. Since then I have added Greek yogurt to me snack regiment too. For tournaments I think I shall sustain on BRAT meals during the day and maybe stuff carbs at night like I used to before fencing tournaments.