High levels of physical activity can help to counteract a gene that normally causes people to gain weight, according to a new study by researchers at the University of Maryland School of Medicine. They analyzed gene variants and activity levels of the Old Order Amish in Lancaster County, Pa, and found the obesity-related FTO gene had no effect on individuals who were the most physically active.
"Our results strongly suggest that the increased risk of obesity due to genetic susceptibility can be blunted through physical activity," the authors conclude. "These findings emphasize the important role of physical activity in public health efforts to combat obesity, particularly in genetically susceptible individuals." The results of the study published in the Sept 8, 2008, issue of the Archives of Internal Medicine.
Soren Snitker, MD, PhD, the senior author and an assistant professor of medicine and pediatrics at the University of Maryland School of Medicine, says, "Our study shows that a high level of physical activity can ‘level the playing field,’ equalizing the risk of obesity between those who have copies of the FTO gene variant and those who don’t."
The FTO gene recently has been linked to obesity and increased body mass index, or BMI, in several large-scale studies. More than half of all people of European descent have one or two copies of a variation of this gene, British scientists reported last year. Individuals with two copies of the gene variant are on average 7 pounds heavier and 67% more likely to be obese than those who don’t have it.
University of Maryland researchers found this same link between variations of the FTO gene and increased risk of obesity in their study of 704 Amish men and women. But, in examining the gene in this unique group of people with a similar genetic background and active lifestyle, the researchers also found that high levels of physical activity helped to counteract the gene’s effects.
"Having multiple copies of FTO gene variants had no effect on body weight for people who were the most physically active, regardless of whether they were men or women. But in less active people, the association between the gene and increased BMI was significant," says Evadnie Rampersaud, PhD, the lead author and a former postdoctoral fellow at the University of Maryland School of Medicine who is now at the University of Miami Institute for Human Genomics. "This provides evidence that the negative effects of the FTO variants on increasing body weight can be moderated by physical activity."
Snitker, of the University of Maryland School of Medicine, says the FTO gene is likely only one of a number of genes linked to obesity and notes that the effect of these genes may have changed over time.
"Some of the genes shown to cause obesity in our modern environment may not have had this effect a few centuries ago when most people’s lives were similar to that of present-day Amish farmers," he says. He adds that environmental and lifestyle factors, such as a high-fat diet and lack of exercise, also may serve as triggers for obesity in genetically susceptible people.
"We are just starting to unravel these complex interactions between genomics and environment. It’s really a new age of discovery," Snitker says. "One day, we hope to be able to provide a personally optimized prescription to prevent or treat obesity in people based on their individual genetic makeup."
In this study, which was funded by the National Institutes of Health (NIH), the researchers examined dozens of variations in the FTO gene. They gauged the participants’ physical activity level with the help of a device worn on the hip called an accelerometer, which measures body movement. "We were able to get objective measurements of physical activity over seven consecutive 24-hour periods using this device, and that is a real strength of our study," says Rampersaud.
The Old Order Amish are considered ideal for genetic research because they are a genetically homogenous people who trace their ancestry back 14 generations to a small group that came to Pennsylvania from Europe in the mid-1700s. They don’t drive cars or have electricity in their homes, eschewing many of the trappings of modern life. Most Amish men are farmers or work in physically demanding occupations such as blacksmithing or carpentry. Women are homemakers who work without the aid of modern appliances and often care for many children.
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[Source: Science Daily]