I do alot of travelling, i am 4 hours from the city, and i use fruit to keep the boredom snacking at bay. apples take me 30mins to eat (on purpose) and grapes are good for popping in the mouth and cut up water melon and honey melon and strawberries.
I also eat cucumbers and whole meal rolls, with turkey or ham.
nothing will make you eat less food, only willpower, and thats something you have to find from within.
i have been to about 6 or 7 parties so far this silly season, and I choose not to even go near the food table. if i dont start, I dont need to know when to stop. I eat before hand, and make sure I am not tempted by having a belly full of water too.
the walking after a meal is a good suggestion, altho games of cricket and even bouche and lawn bowls are good too.... anything to keep from picking at the leftovers.
offer to clena up and gladwrap everything and pack away, so theres none of that food sitting in front of you tempting you to just have one more slice.
its just me hubby and our 5 kids this christmas so I am in charge of cooking. I am lucky