If you are concerned about gaining weight over Christmas there are a few simple changes you can make to the vegetables you eat on Christmas Day that can reduce the carbohydrates that you consume, meaning that you will be less likely to be storing fat and gaining weight.
The vegetables you should be eating less of are potatoes, carrots and parnsips.
So when you are planning the vegetables for the big Christmas meal, make sure you provide plenty of dark green leafy vegetables (Brussel sprouts, brocolli, spinach, kale), cabbage, peas and beans, so that you can fill up on these rather than starchy vegetables.
Maybe restrict yourself to a couple of roast potatoes and a few carrots and parnsips, with plenty of Brussel sprouts.