I had this dilemma, and what I did was fill up on stuff at the party that I could- the food was all mexican, so mostly I had beans and salsa and salad lol, then I have a few bites of other stuff, I didn't go crazy and stuff myself with tamales and enchiladas. Then I added a day on the end
Make sure you are getting those egg whites and brown rice and beans in, because that's what helps you stay full. Lentils saved my butt for the first week of the diet- I made a HUGE pot and ate a bowl everyday for lunch.