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Inactivity
Blamed for Teens' Weight Gains
Over two decades, teenagers have been getting fatter because
they have been exercising less, not because they have been
eating more, a study says.
Researcher Lisa Sutherland of the University of North
Carolina at Chapel Hill analyzed federal data on the diet,
weight and physical activity of teens, ages 12 to 19. From
1980 to 2000, calories eaten rose 1 percent and obesity
rose 10 percent, while physical activity dropped 13 percent.
Those percentages show that teenagers must have been getting
fat primarily because they burned fewer calories. "If caloric
intake is flat and physical activity is declining, there
is a cause and effect relationship there," Sutherland said.
She presented her findings last month in San Diego at
a scientific conference of the Federation of American Societies
for Experimental Biology. However, although other experts
accept the idea that teens have become less active, the
experts find it hard to swallow the conclusion that teens
have not been overeating as well.
Sutherland looked at three large federal surveys. Data
on weight came from the National Health and Nutrition Examination
Survey, and data on physical activity was from the Youth
Risk Behavior Survey, both maintained by the Centers for
Disease Control and Prevention. Data on caloric intake was
from the Nationwide Food Consumption Survey maintained by
the Agriculture Department.
The study said that teenagers ate an average of 2,290
calories a day over the 20 years. It also said that while
42 percent of teens reported doing at least 30 minutes of
physical activity on a typical day at the start of the study,
only 29 percent did at the end.
The study was funded by an unrestricted grant from the
National Soft Drink Association. But Sutherland said that
in keeping with university rules, the association had no
control over any aspect of the research.
"I was trained as a nutritionist," Sutherland said. "The
data kept coming out that caloric intake was basically flat,
but there was a huge drive to look at diet. I said, 'Let's
look at physical activity.'"
It's not surprising that teens have become less physically
active, Sutherland said. Today's kids have more and better
computers and video games, and less school physical education
or after-school play, she said.
"I remember wanting to go outside the minute the sun came
up, and my parents dragging me to go inside at sunset,"
said Sutherland, who is 35.
She noted that her study was limited because the three
surveys had differing methodologies, and the decline in
physical activity was based on students' self-reports.
While they accept Sutherland's idea that teenagers are
burning too few calories, some outside observers think the
report underestimates the damage also done by bad diet.
"I would take exception to that 1 percent (increase in
calories)," said Dr. Reginald Washington, of Denver, who
chairs the sports medicine and fitness committee of the
American Academy of Pediatrics. "I think it's much higher
than that."
Fast food calories are a big part of teens' eating patterns,
and supersizing is making the portions grow, Washington
said.
"We are pretty sure they are eating too much, no matter
what the data say," said Dr. Nancy Krebs of the University
of Colorado Health Sciences Center in Denver, who chairs
the pediatricians' group's committee on nutrition. "There
is quite a consensus that it is due to a combination of
factors."
"Our view is that it is a complex issue," said clinical
nutritionist JoAnn Hattner of Stanford University, a spokeswoman
for the American Dietetic Association. "It may well be their
activity is down, and for some it may be a combination of
increased caloric intake and decreased activity."
Accepting the conclusion that food is not a big part of
the problem could take pressure off food companies to cut
the calories they feed the nation, Hattner said.
"There is enough clamor throughout the country that we
are getting corporations to change," Hattner said. "We need
to continue that clamor."
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On the Net:
Youth Risk Behavior Survey: http://www.cdc.gov/nccdphp/dash/yrbs/2001/youth01online.htm
National Health and Nutrition Examination Survey: http://www.cdc.gov/nchs/nhanes.htm
Nationwide Food Consumption Survey: http://www.barc.usda.gov/bhnrc/foodsurvey/home.htm
Article
Source: Associated Press
Article Author: Ira Dreyfuss
Net Reference 102
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