WEDNESDAY, March 14 (HealthDay News) -- People who walk briskly
an hour a day could beat back a genetic predisposition to be
overweight, compared to those who plant themselves in front of the
TV, new research suggests.
The findings don't prove that the exercise is the specific
factor that makes a difference, because it's possible that
something else could explain why those who walked were thinner, the
researchers stressed. Also, the difference would amount to less
than a pound for many people.
Still, "the message is that while we cannot change genes, we can
do something to change the influence of genes by increasing
physical activity and reducing sedentary behavior," said study
author Qibin Qi, a research fellow with the department of nutrition
at the Harvard School of Public Health.
Research has suggested that inherited traits may be responsible
for 50 percent of obesity cases, Qi said. As scientists study what
makes people fat from a biological point of view, one of the big
issues is this: How can you turn back a genetic tide that may make
you more likely to put on pounds just because you were born to a
specific set of parents?
In the new study, Qi and colleagues tried to tease out an
answer. They came up with one, although it has caveats.
The researchers analyzed the results of two studies that tracked
about 7,700 female and 4,600 male health professionals. The studies
included data about how much time the people spent watching TV and
walking in the two years prior to their weight being measured.
The researchers looked at a measurement called body-mass index
(BMI) that analyzes whether a person's height and weight are
proportional. The formula is kilograms/meter squared
Genes that have been linked to obesity boosted weight by 0.13
Those who briskly walked an hour a day had a 0.06 kg/m-squared
decrease in the genetic effect. For each two hours a day people
spent watching TV, the BMI went up by 0.03 kg/m-squared.
The differences wouldn't amount to much for many individuals. A
6-foot-tall person who weighs 200 pounds would have a BMI of 27.1,
and an increase of one pound would boost the BMI to 27.3 -- a 0.2
So should you take an hour-long walk every day to beat back our
"We don't know whether it is
just physical activity that reduced the genetic risk, or
whether a generally healthy lifestyle would have the same effect,"
said Ruth Loos, director of Genetics of Obesity and Related
Metabolic Traits at the Mount Sinai School of Medicine. "After all,
people who are physically active tend to eat more healthily and
smoke less, etc., but in these types of studies the contribution of
these different aspects of a healthy lifestyle are hard to tease
The study was scheduled to be presented Wednesday at an American
Heart Association meeting in San Diego. Data and conclusions should
be viewed as preliminary until published in a peer-reviewed
For more about
obesity, try the U.S. National Library of Medicine.
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