The researchers advise parents to heed recommendations from the American Academy of Pediatrics (AAP) about limiting kids' TV time.
The AAP doesn't recommend TV for children aged 2 or younger. The AAP recommends no more than one to two hours per day of educational, nonviolent programs for older children.
Other tips include removing TVs from children's bedrooms and forbidding TV watching while eating, note the new study's authors, who included Perrie Pardee and Jeffrey Schwimmer, MD, of the pediatrics department at the University of California, San Diego.
Television and Obese Children
The children sought obesity treatment between 2003 and 2005 in San Diego, San Francisco, or Dayton, Ohio.
The kids' parents reported how much TV their child watched on a typical day. Children aged 8 and older helped their parents report TV time.
More than three-quarters of the kids -- 78% -- reported watching at least two hours of TV per day.
The heaviest children were the most likely to have a high blood pressure reading -- and to watch lots of TV.
Children who watched 2-4 hours of TV per day were 2.5 times as likely as kids who watch no more than two hours of daily TV to have high blood pressure.
Cause and Effect Unclear
The study, which is due to appear in December's edition of the American Journal of Preventive Medicine, has some limits.
As an observational study, it doesn't prove cause and effect. That is, the findings don't prove that watching TV raised the kids' blood pressure; other factors may have been involved.
An editorial published with the study raises these questions for further research:
- Why is obesity increasing while TV viewing isn't increasing?
- Why does obesity increase in adolescence, when TV viewing decreases?
- Why do boys, who watch more TV than girls, show less obesity and more physical activity?
"Focusing on just one set of behaviors may not be enough," writes editorialist Stuart Biddle, PhD.
For instance, Biddle points out that turning off the TV doesn't make for a more active child if that child just starts playing computer games.
Biddle works at the School of Sport and Exercise Sciences at Loughborough University in Leicestershire, England.