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September 9, 2008 9:47 PM
By Julie Steenhuysen
CHICAGO - Vigorous physical activity can help
even people genetically prone to obesity keep the weight off,
U.S. researchers said on Monday.
They said a study among a group of Amish people found those
who had an obesity-related gene called FTO but were very
physically active weighed about the same as others who did not
carry the gene.
"When we looked at the Amish who were the most active,
there is suddenly no effect of that gene," said Dr. Soren
Snitker of the University of Maryland, whose study appears in
the Archives of Internal Medicine.
The findings, which suggest physical activity can overcome
a genetic predisposition for obesity, may help inform the
debate over whether changes in diet or physical activity will
make the biggest difference in fighting obesity.
Consumer groups have pushed for laws such as July's
moratorium on new fast-food restaurants in certain Los Angeles
neighborhoods, while the food industry often maintains that a
lack of exercise is more to blame.
Researchers focused their study on a group of 704 Old Order
Amish men and women in Lancaster County, Pennsylvania, a
religious group whose members often do not drive cars or have
electricity in their homes.
Snitker said the group offered a unique mix of activity
levels, with some farmers in the community still using
horse-drawn plows while others holding more conventional jobs,
including factory work.
He and colleague Evadnie Rampersaud of the University of
Miami were looking to see if physical activity in this group
might offset the effects of the fat mass and obesity associated
with the FTO gene, found in more than half of all people of
European descent.
RISK OF OBESITY
People with two copies of the FTO gene on average weigh
nearly 7 pounds (3 kg) more and are about 70 percent more
likely to be obese than those who do not have the gene.
The volunteers wore a device called an accelerometer to
track motion for a week.
The researchers compared body mass index or BMI, a measure
of weight to height, and found those who were less active and
had the FTO gene variant were significantly more likely to be
overweight or obese.
But among the most physically active, the FTO gene made no
difference.
Snitker said the study gives some perspective on how the
obesity epidemic has evolved, as modern conveniences have
reduced the need and opportunity for physical activity.
People in the most physically active group expended about
900 more calories per day than the low-activity group. That
would equal three to four hours of moderately intense physical
activity such as brisk walking, house cleaning or gardening.
"We probably carry genes that 150 years ago were not risk
factors for obesity, but because of changes in our environment,
they become liabilities," he said.
Snitker believes societies should step in to make more
opportunities for what he called "free" exercise, making it
easier to walk or bike to work, or to use public transportation
that requires some walking.
The World Health Organization estimates 1.6 billion adults
worldwide are overweight and at least 400 million adults are
obese. That includes a third of all U.S. adults.
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