Experts at the University of Bath have found that exercising for 45 minutes a day during a period of over-eating can stabilise blood sugar levels and prevent damage to metabolism - even if the amount of calories consumed is "significantly" more than those burned off.
In tests on exercising and non-exercising groups who both consumed extra calories, the group that remained inactive showed an unhealthy decline in their blood sugar control, while the exercising group - whose calorie intake was 25% higher than the inactive group - had stable blood sugar levels.
Researcher Dr James Betts, writing in the Journal of Physiology Today, said: "This new research shows that the picture is more sophisticated than 'energy' alone. Exercise has positive effects even when we are actively storing energy and gaining weight."
Dr Dylan Thompson, senior researcher, added: "If you are facing a period of overconsumption and inactivity this Christmas, then our study shows that a daily bout of exercise will prevent many of the negative changes in the way in which your body handles sugar, even if you do still gain weight."