A strict exercise regime of watching 33 hours of television will be enough to work off the calories of this year's Christmas dinner, scientist has calculated.
TV's Jim Royle getting ready for a marathon workout session
A trek from the Gwynedd village of Beddgelert to the top of Snowdon and back will also burn away the turkey, gravy, stuffing, sausage wrapped in bacon and Christmas pudding that most of us will consume.
Professor Joe Doust of the University of Wales Aberystwyth says a typical person can expect to eat about 2000 calories in a day.
But a full Christmas dinner with all the trimmings, preceded by breakfast, a few sneaky chocolates while watching the Queen's speech, and the usual cold supper can tip the scales at a belt-straining 6000 calories.
Based on a 2000 calorie Christmas dinner, Prof Doust has calculated that a man weighing 12 stone eight pounds will need to walk 18 miles - or a woman of 9 stone 6 pounds 24 miles - to burn off those excess calories.
Alternatively, those who favour the couch potato option will need to watch 33 hours of television, an activity which burns calories at a rate of one per minute.
But the good news for those of us already struggling to see our toes is that a light person will have to walk further than a heavy person to burn off the same number of calories.
"The number of calories burned while walking depends on body weight, distance, type of surface and the slope," said Prof Doust.
"Also, you will have to walk further on flat land than hilly terrain to burn off the same calories."
And people with long legs burn more calories than those with short legs, claims Prof Doust.
"You might take more steps but each one is shorter and needs less energy than the longer steps of a taller person."
The Christmas dinner burn off
Golf 6 hours 40 minutes
Football 3 hours 20 minutes
Swimming 4 hours 10 minutes
Horse riding 6 hours 30 minutes
Cycling 4 hours 45 minutes
Gardening 7 hours
Housework 7 hours 24 minutes
Dancing 4 hours 46 minutes
Fishing 11 hours 42 minutes
Watching television 33 hours
"The calories you burn walking doesn't seem a lot, but if you walk on a daily basis the calories soon mount up."
The academic's latest work on calories follows on from the Aberystwyth Calorie Map which he published in July 2002.
The map features 15 walks in and around the seaside town and calculates the average number of calories burned.
Since it was launched Prof Doust and his team have mapped more than 80 walks for clients in the UK ranging from city centres to large forests.
For his Christmas walk calculations Prof Doust assumed a typical winter path where it is wet, muddy in places and windy.
He reckons that someone weighing 70 kg will need to walk 33 km to burn off their Christmas dinner and someone weighing 100 kg will need to trudge 23 km.