If one of your favourite pass-times over the holiday is eating food you would not normally permit yourself then this advice might not be for you... or maybe its tailor made for you. Those in our industry should be familiar with the contribution that excess weight makes to a whole range of disorders: from the big ones such as cancer and heart disease to any number of other minor disorders. This article highlights the benefits of choosing smaller portions. Link.
I typically put on about 2kilos over Christmas. My nutritionist tells me that is roughly 16,000 excess calories (this link for calculations) - or 38 Starbucks muffins. I think I've done well to get it down to that.
While there are all sorts of diet tricks, and you should certainly use whatever strategy works for you, there is one, really simple one: eat less. That means that for me I can still enjoy the range of foods, but I choose a smaller portion. I'm aiming for less than 2 kilos this time.