stop quitting

I do ok with my overeating if i can plan and prep my food, but this weekend i was at a conference where the food was preset and i was not able to avoid the food when it was sitting in front of me. i tried to just not eat and was successful skipping breakfast but i got VERY physically hungry and i chose to eat the off plan food for lunch. i need help figuring out what to do when i am physically hungry and there is free off plan food sitting in front of me.