The common 'fat gene' can be overcome with a little exercise

Even if they've inherited "the fat gene," people don't have to be overweight if they have a relatively small amount of physical activity, such as walking their dog, a study has found. (Getty Images photo)

The research, published this month in the journal of PLoS Medicine, reviewed dozens of studies about the fat mass and obesity-associated gene, which is very common. "By most estimates, about 65 percent of people of European and African descent and perhaps 44 percent of Asians carry some version of the FTO gene," reports Tara Parker-Pope of The New York Times.

But physical activity, even a small amount, may counter the effects of the gene, reducing reduced the effect of the FTO by 30 percent. "While that still leaves 70 percent of the potentially fat-encouraging effect of the gene intact, the consequences of physical activity on the workings of this single gene seem to be substantial enough to perhaps allow someone who otherwise would become seriously overweight to maintain a normal waistline," Parker-Pope reports.

Scientists are still stumped by how the FTO encourages weight gain, but know the gene is particularly active in the the regions of the brain "that regulate the balance of energy intake and expenditure," said Dr. Lu Qi, assistant professor in the department of nutrition at the Harvard School of Public Health. "The loss of energy balance is the basis of development of obesity."

Physical activity, though, my counteract that. "Biologically, it is possible these two factors, genes and physical activity, may interact in affecting energy balance," Qi said. And exercise might affect how the FTO gene works, influencing "whether it expresses certain proteins or remains quiet," Parker-Pope reports.

Though researchers are being cautiously optimistic, they hope the implications of the findings will be encouraging. "Often people feel that obesity runs in the family or that obesity is in their genes, and therefore feel they have no control over their weight issues," said Dr. Ruth Loos, a program leader at the Institute of Metabolic Science in Cambridge, England. "Our study shows that physical activity plays a role in weight control, even in those who are genetically predisposed." (Read more)