It is a fact that we are geared genetically to gain weight during the winter months. This is to help our bodies tolerate cold winters. Of course our genes don't know about central heating so it keeps telling us to eat for the winter. That is one of the main reasons that most feast days for humans have been historically in the winter months.
We must consciously make the decision to eat wisely during our feasting holidays. Eat small meals and don't pig out on odd burlesque pasties for sale or cakes that are very rich in creams and sugars. I am not saying you should avoid them entirely, no, just eat taster sizes. Don't eat a whole slice of cheese cake, cut it in half and share it.
Eat and savor each small bite and you'll find that the holiday season will be good to your body.