Can we enjoy the Christmas holidays without gaining weight?

December’s eating and drinking extravaganza is in full swing — extra lunches out, Christmas parties, mince pies in the office, Quality Street at the hairdresser’s, festive tipples with friends.
And Christmas Day isn’t even here yet, the apex of all this culinary imbibing, the day we feel duty-bound to gorge, the day on which experts say we amass 6,000 calories, about three times what we eat on an ordinary day.