Christmas day has to be one of the most food-filled days of the year. For many of us, it will kick off with a full Irish breakfast quickly followed by a chocolate from the advent calendar, mince pies and cups of tea - and that's all before the main event. 

One person who won't be rolling themselves off the couch on December 25th is Operation Transformation fitness expert, Karl Henry who insists that Christmas is no excuse to go off the rails.

"Christmas is the time of year that people classically put on, generally, from four to seven pounds. There are a couple of things that people can do to ensure they don't do that," says Karl.

"In terms of gear, obviously, a really good wind-proof and rain-proof jacket. If you're exercising, high-vis is crucial whether you're walking or cycling.

"Non-cotton based fabrics are really good. Cotton is terrible for cold weather because it gets heavy and damp so go with the lycra fabrics, sports fabrics and dry fit fabrics - they're well worth the money that you spend on them because they will keep you much more comfortable when you're exercising.

"Around Christmas, we tell our clients to do one hour a day of something. Whether it's a walk or a cycle - some fancy a surf at Christmas, they're mad. An hour a day of something will burn four or five hundred calories and that will balance out some of the treats."

"Definitely exercise on Christmas day. Get it out of the way early. I get up for an hour-hour and a half run in the morning, come home, get a shower and I can enjoy the rest of my day and have whatever I want. It's just another day, get it done early and you feel great for the day."

So, there you have it. If you want to follow in the footsteps of a fitness expert, get those runners on!