TV Bad for Obese Kids' Blood Pressure?

Oct. 30, 2007 -- A new childhood obesity study links watching lots of TV to high blood pressure in obese children.

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

Pardee, Schwimmer, and colleagues studied 546 obese kids and teens (average age: almost 12).

The children sought obesity treatment between 2003 and 2005 in San Diego, San Francisco, or Dayton, Ohio.

The kids had an average BMI (body mass index, which relates height to weight) of 35.5, putting them in the top 5% of BMI for their age and sex.

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 children got their blood pressure recorded once for the study. Nearly half of the children -- 43% -- had a blood pressure reading that was in the hypertension range.

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.