Scientific evidence is increasingly proving that the human body was engineered for action. Researchers at the University of Maryland School of Medicine have recently added more evidence, with their study of the effect an active lifestyle has on a specific gene that causes less active people to gain excess weight.

The obesity-related FTO gene is common in people of European ancestry, with about half of all descendants from the continent carrying at least one variation of the gene. People who carry two copies of the gene are 67% more likely to gain weight to the point of obesity, measured at a body mass index (BMI) of 30 or higher. A BMI of 25 to 30 defines a person who is overweight.

To test the theory that a physically active lifestyle can offset the weight-gaining effect of the FTO gene, the Maryland research team turned to their semi-cloistered Amish neighbors in Lancaster County, Pennsylvania. Members of the Old Order Amish can trace their ancestry back 14 generations, to their forefathers’ arrival in the United States from Europe.

The Amish are as well known for their simple lifestyles of hard work using few, if any, tools of modern convenience as well as their genetic seclusion. Their traditional diet consists of fresh foods grown and produced within their own communities but it tends to be high in both cholesterol and fat, much like the typical American diet.

The University of Maryland study involved 704 Amish men and women who agreed to wear an accelerometer to measure their bodies’ movements during seven 24-hour periods in a row. Investigation of high and low activity levels among the Amish showed the most active members of the community burned 900 more calories each day than their less active brethren. Nine hundred calories is the equivalent of three or four hours of moderate intensity activity, such as gardening, housecleaning, or walking briskly.

A simple lifestyle involving a high degree of active physical labor doesn’t exclude the Amish from the effects of the FTO gene, however. Amish people are just as likely to be overweight or obese as the rest of the American population, with 10.1% of the men and 30% of the women in the study group classified as obese according to their BMI. In addition, 54% of the men and 63% of the women are overweight.

Even though the Amish study participants closely matched the general US population for excess weight and obesity, they didn’t suffer the same consequences as so many Americans do. Their rate of type 2 diabetes is only about half that of the general American population and their cholesterol counts are healthier, too. The Amish people who led the most active lifestyles were in better health than their less active family members.

The University of Maryland research team, led by Soren Snitker, MD, PhD, says the obesity epidemic sweeping the country is much too complex to attribute to exercise and the FTO gene alone but their study clearly indicates exercise has the potential to offset the tendency to gain weight in people who do carry one or more variations of the FTO gene.

The Archives of Internal Medicine carries the full story of the University of Maryland study in its September 8 issue.