A daily bout of exercise can counter the harmful effects that short-term inactivity and overeating have on health, according to a new study published in The Journal of Physiology.
Evidence already exists that even a few days of consuming more calories than you burn can be harmful to health.
The new study, from the University of Bath in the UK, takes a step further and suggests a daily dose of exercise can bring health benefits that go beyond just helping to burn off excess calories.
Speaking about their work, co-author Dr. James Betts says:
"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."
He and his colleagues invited 26 healthy, normally active young male volunteers, aged from late teens to early 30s, to consume more calories than normal for a week.
Researchers found that daily exercise counteracts negative health effects of short-term inactivity and overeating.
Half of the volunteers were asked to restrict their physical activity (to below 4,000 steps per day), in order to generate an energy surplus, and the other half were asked to run for 45 minutes per day on a treadmill (at 70% of maximum oxygen intake).
The inactive group was asked to consume around 50% more calories than normal, while the exercise group was asked to consume 75% more, so that everyone's net daily energy surplus was the same.
At the start and the end of the week, the volunteers gave fasting blood samples, underwent oral glucose tests and also had small samples taken of abdominal fat.
Unhealthy declines in blood sugar control
After just 1 week, the differences between the two groups were striking.
The inactive group showed a significant, unhealthy decline in blood sugar control, and their fat cells were over-expressing genes linked to disrupted nutritional balance and unhealthy metabolism, and under-expressing genes linked to healthy metabolism.
However, these effects were markedly less in the exercise group: their blood sugar levels remained stable, and while their fat cells did show some changes in gene expression, these were significantly less "undesirable."
The researchers conclude:
"Vigorous-intensity exercise counteracted most of the effects of short-term overfeeding and under-activity at the whole-body level and in adipose tissue, even in the face of a standardized energy surplus."
Despite consuming more calories, exercise group was still better offSenior author Dr. Dylan Thompson says:
"A critical feature of our experiment is that we matched the energy surplus between groups - so the exercise group consumed even more energy and were still better off at the end of the week."
He suggests the message from this study for those entering a period of overconsumption and inactivity, such as that faced by Christmas revellers, is that "a daily bout of exercise will prevent many of the negative changes from taking place even though you are gaining weight."
This study shows the effects clearly in a group of young men. However, further research is now needed to find the underlying causes, and also to see if the same happens in other groups, like women and older adults, and whether less training has the same result.
Another study published recently suggests playing exercise video games can help glucose control in people with type 2 diabetes. The researchers compared a group who used the Wii Fit Plus exercise game with a group who received standard care.