Children and teenagers who spend lots of
time in front of screens especially TVs tend to gain more weight as they age,
according to a new study.
The findings are consistent with research
suggesting all that idle sitting and exposure to advertisements may fuel poor
eating habits. Many parents believe their children are getting a reasonable
amount of recreational screen time, Mark Tremblay said.
But most US and Canadian kids exceed the
recommended two-hour maximum per day. "We don't pay attention to the fact
that it's half an hour here, half an hour there, an hour here, an hour
there," Tremblay told Reuters Health. He is the director of Healthy Active
Living and Obesity Research at the Children's Hospital of Eastern Ontario
Research Institute in Ottawa, Canada, and wasn't involved in the new study.
Researchers used data from a long-term
study of kids who took surveys every other year. The surveys included questions
about their height and weight as well as how much time they spent watching TV
and DVDs and playing computer and video games.
Kids were between ages nine and 16 when the
study started. Out of about 4 300 girls in the study, 17% were overweight or
obese. 24% of the 3 500 boys were also above a healthy weight.
From one survey to the next, each one-hour
increase in children's daily TV watching was tied to an increase of about 0.1
points on a body mass index (BMI) scale, which measures weight in relation to
height. That's a difference of approximately half a pound (227g) per extra hour of TV.
Increases in total screen time between
survey periods were linked with similar but smaller changes in BMI."The
weight of the evidence is pretty strong that television viewing is related to
unhealthy changes in weight among youth," Jennifer Falbe said.
But, she told Reuters Health, "It's
important for parents to be aware of all the potentially obesogenic screens
that they should really be limiting in their children's lives." Increases
in DVD and video watching were tied to weight gain among girls, in particular.
Falbe led the study while at the Harvard
School of Public Health in Boston. She is now at the University of California,
Berkeley School of Public Health. When kids watch TV, "There is more
purposeful, deliberate exposure to eating options, commercials that come on
that might cue you to go off to the pantry and grab a cookie or a soft
drink," Tremblay said.
"Typically your hands are free when
you're watching TV, so should that temptation capture you, you're able to sit
there and munch, whether it's a healthy or an unhealthy snack. "What's
more, he said, "You can get into a pretty hibernative state on the
couch." Even if kids are sitting down while playing a computer game, for instance,
they might be a bit more active, Tremblay said.
The study didn't include many non-white or
poor children, the researchers noted. So the findings may not apply to all US
Another study of factors affecting children’s'
weight published today in Paediatrics found that kids whose mothers and fathers
reported consistent parenting – setting age-appropriate rules and expectations
and following through on them – had a lower BMI than their peers. But those
differences were small, Pauline Jansen from Murdoch Childrens Research
Institute in Melbourne, Australia, and colleagues wrote.
In a third report in the same journal
issue, researchers from the Centres for Disease Control and Prevention tracked
1.2 million children from low-income families in the US to see how their weight
changed over time.
found 11% of kids who were not obese before age two became obese over the next
two to three years. Close to two-thirds of children who were initially obese as
babies and toddlers were no longer obese a couple of years later.
Hispanic and American Indian/Alaska Native
children were more likely than white kids to become obese and less likely to
stop being obese. The study "underscores the importance of early life
obesity prevention in multiple settings for low-income children and their
families," according to researchers led by Dr Liping Pan.