RESEARCH shows that just a few days of eating too much and exercising too little can cause long-term effects on the body.
But a new study has found this can be countered by a 45-minute daily workout - even if the amount of calories consumed is "significantly" more than those burned off.
Experts at the University of Bath found exercising during a time of excess can stabilise blood sugar levels and prevent damage to metabolism.
A critical feature of our experiment is that we matched the energy surplus between groups, so the exercising group consumed even more energy and were still better off at the end of the week.
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.
In the study, carried out by researchers at the university's department for health, 26 healthy young men were asked to reduce their physical activity over a period of one week.
Half of the group then exercised daily on a treadmill for 45 minutes, while the other half remained inactive. Everyone involved in the study was asked to overeat.
The non-exercising group increased their calorie intake by 50 per cent, while the exercising group increased theirs by 75 per cent - ensuring all of the participants' daily energy surplus - the extra calories they received beyond what they burned - remained the same.
After just one week, both groups had their blood insulin measured and biopsies of fat tissue taken.
The non-exercising group showed an unhealthy decline in their blood sugar control, while the exercising group had stable blood sugar levels.
The activation of genes within the fat cells in the non-exercising group were also found to be negatively changed to levels needed for a well-functioning metabolism.
Dr James Betts, one of the researchers who worked on the study, added: "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."
Short-term overfeeding and reduced physical activity had a dramatic impact on the overall metabolic health of the participants and on various key genes within fat tissue.
"However, even though energy was still being stored, regular exercise prevented many of the long-term negative changes from taking place.
