A stroll after Christmas dinner is part of many families' festive timetable - but heart experts say a pre-dinner walk is a good idea.
Have you walked far enough to be able to tuck-in?
Glasgow University research for the British Heart Foundation found it could help reduce the damage done by too much Christmas pudding.
It says a 90-minute walk lowers fat levels in the blood and improves blood vessel function.
The study is published in the Journal of the American College of Cardiology.
They said the health benefits of a long stroll remained even after the walker had eaten a high-fat, high-carbohydrate meal.
The researchers studied 10 lean and 10 obese middle-aged men.
Each was tested twice for his response to a fatty meal, with the tests performed a week or two apart.
On the afternoon before one of the tests, each man walked on a treadmill for 90 minutes. In the second test, no exercise was done.
How exercise helps
The researchers found that both lean and obese men benefited from taking exercise.
Levels of triglycerides (blood fats) were reduced by 25% both before and after the fatty meal.
The researchers also looked at the endothelium, the inner wall of the blood vessels which provides an important defence against the build-up of fatty deposits inside the blood vessels.
These deposits can disrupt blood flow and lead to a heart attack.
Exercise appeared to improve the function of the endothelium by 25% before the meal and 15% afterwards.
The researchers say that, as well as offering a timely reminder about the counteracting a rich diet with plenty of exercise, their findings suggested some possible explanations for its protective effects.
They said it showed that exercise can both improve the way the body metabolises food and help blood vessels resist the harmful effects of fatty foods.
And that it demonstrated that just one exercise session can provide immediate benefits that last at least a day.
'Any exercise beneficial'
Dr Jason Gill, who led the research, said: "Just one brisk walk substantially improved blood vessel function both before and during the hours after eating a fatty meal and the exercise improved the body's handling of dietary fat to the same extent irrespective of whether someone was lean or obese.
"The differences observed in blood fat levels and in blood vessel function after just one workout are remarkable, particularly as these were evident for at least 24 hours after the exercise."
He added: "Ninety minutes of exercise is a long time.
"But it is important to note that the exercise was not strenuous and even obese men, who were unused to exercise, completed the walk without difficulty."
Dr Gill said many people may not be able to fit such long walks into their lives.
But he said: "Thirty minutes of exercise or several smaller bursts of activity are still beneficial.
"The size of the benefit is related to the number of calories burned during exercise, so any exercise you do will be beneficial - it is just that if you do twice as much, you will get twice the benefit."
Professor Peter Weissberg, Medical Director of the BHF, said: "Although larger studies are needed to confirm these findings, this study provides clues about the possible mechanisms behind the well-established fact that regular exercise is good for your heart.
"There are no surprises in the fact that eating fatty food increases the amount of fat in your bloodstream - and we would discourage consuming such diets with any regularity.
"But if you are going to over-eat at Christmas, it would be worth considering going for a good long walk first - as this at least can undo some of the damage the over-indulgence is about to cause."