You can have your cake and eat it too! Eat light before the party. Make your balanced plate. If you still want to indulge, only have a 1 or 2-bite taste of the offerings. Take half your cake or your plate home to enjoy tomorrow. Choose what you really want or know you'll enjoy.
Sit away from the food table so you are very aware of how many times you are going up. No one wants to conspicuously miss out on the tasty party, so don't! Have some there and some at home!