If you think about it most of a turkey dinner is healthy just don't eat go easy on the carbs and you should be alright. It's the trimmings the chocs. mince pies, cakes, booze etc. and the temptation to eat ALL the time which is not brilliant.
I usually say 'oh fxxx it' for 2 or 3 days and start on my healthy regime again immediately afterwards (I take echinacea and nettle supplements to help me detoxify) The Paul Mckenna diet that i'm on is brilliant for xmas 'cos you can eat little and often on it.
Try not to eat too much of it would be my suggestion. Also, have a good, filling breakfast each day (maybe poached eggs and bacon) so that you're not tempted to snack too much. And also take some extra exercise to counteract any indulgence (although burning 100 cals takes a lot more walking than you might think!).
Nuts and seeds are good sources of protein, but you can eat a lot in one go.
Following on from a previous thread; how do I not gain wieght over Christmas. I love my food; especially festive food but how do I do it? Any festive but non too fattening treats? My idea is cold meats and pickles with cheese; high protein/low carb.