From MedPage Today...

One could claim that this reported study on the value of 1 hr of daily
exercise supports the recent 60 minutes a day of moderate or vigorous
exercise in recent guidelines for adolescents from the U.S. Department
of Health and Human Services.
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Exercise Can Beat Obesity Gene

By Michael Smith, North American Correspondent, MedPage Today
Published: April 05, 2010
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine,
University of California, San Francisco.
    
Action Points

    * Explain to interested patients that this study suggests that
exercise can overcome the effects of a gene known to predispose people
to obesity.
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An hour a day of moderate to vigorous exercise can overcome the effect
of a gene variant that predisposes people to obesity, researchers said.

In a cohort study of 752 European adolescents, those who had one or more
copies of the variant -- but exercised daily -- were no more likely to
be overweight than those who did not have the variant, according to
Jonatan Ruiz, PhD, of Sweden's Karolinska Institute, and colleagues.

They implication, they said in the April issue of Archives of Pediatrics
& Adolescent Medicine, is that recommended exercise levels can
"ameliorate the deleterious effect" of the gene variant.

The gene variant in question -- dubbed rs9939609 -- is the so-called A
allele of the fat mass- and obesity-associated gene, or FTO. Each copy
of the A allele has been estimated to correspond with an extra 1.5
kilograms in body weight.

Some studies have shown that exercise benefits people carrying one or
more copies of the allele, the researchers said, but others have not
found an effect.

To help clarify the issue, they turned to a cross-sectional study known
as Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA),
designed to obtain data on nutrition and health-related parameters.

Of the 3,865 adolescents in the study, 752 adolescents (including 413
girls) had data on the FTO variant, body mass index, and physical
activity as measured by accelerometers over a seven-day period.

The researchers divided the group according to whether they achieved the
60 minutes a day of moderate or vigorous exercise in recent guidelines
for adolescents from the U.S. Department of Health and Human Services.

Overall, they found, 200 of the 339 boys and 111 of the 413 girls
reached the recommended daily exercise level.

Of the 752 adolescents, 275 had no copies of the allele, 354 had one
copy, and 123 had two, Ruiz and colleagues reported in the journal, but
there was no significant difference among the FTO genotypes in terms of
how many of the participants met the exercise cutoff.

On the other hand, among those who did not meet the cutoff, there was a
significant effect on obesity-related factors. Specifically, after
adjusting for center, sex, and age, the A allele was associated with higher:

    * Body mass index -- at plus 0.65 perallile]copy, which was
significant at P=0.005
    * Body fat percentage -- at plus 1.70% per [allile]copy, which was
significant at P=0.003
    * Waist circumference -- at plus 1.15 centimeters per[allile]copy,
which was significant at P=0.04

On the other hand, there were no significant differences in those
parameters -- based on FTO status -- among participants who met the
exercise level, the researchers said.

Results were similar in boys and girls and did not change when the
researchers adjusted for pubertal stage, rather than age.

Ruiz and colleagues said the study is cross-sectional, so the findings
should be interpreted with caution.

The study had support from the European Community Sixth RTD Framework
Programme, the Spanish Ministry of Education, the Spanish Ministry of
Health, the Swedish Council for Working Life and Social Research, and
the ALPHA study (a European Union-funded study in the framework of the
Public Health Programme).

The researchers made no financial disclosures.

Primary source: Archives of Pediatrics & Adolescent Medicine
Source reference:
Ruiz JR, et al "Attenuation of the effect of the FTO rs9939609
polymorphism on total and central body fat by physical activity in
adolescents: The HELENA Study" Arch Pediatr Adolesc Med 2010; 164(4):
328-33.

http://archpedi.ama-assn.org/cgi/content/short/164/4/328