MONDAY, Aug. 6, 2018 (HealthDay News) -- Kids are spending more time than ever in front of screens, making it more likely they'll become overweight or obese, a new review claims.

The average 8- to 18-year-old spends more than seven hours a day fixated on a screen, whether it's a computer, smartphone, tablet, video game or TV, the latest evidence shows.

Teenagers who exceed two hours daily of recreational screen time are nearly twice as likely to be overweight or obese, the review showed. Excess weight increases the risk of heart disease, diabetes and other health problems.

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"Total media use increased by about 20 percent from 1999 to 2009, with most of that jump happening since 2004, and driven mainly by increases in computer use," said study lead author Tracie Barnett. She's a researcher at the INRS-Institut Armand Frappier and Sainte-Justine University Hospital Research Center in Montreal.

This and other evidence supports the American Heart Association's longstanding recommendation that children and teens get no more than two hours a day of recreational screen time, Barnett and her colleagues concluded.

"The more time you spent on these screen-based devices, the greater the odds of being overweight or obese," Barnett said.

The percentage of obese kids in the United States has more than tripled since the 1970s to include nearly 1 in 5 school-age children, according to the U.S. Centers for Disease Control and Prevention.

But the TV is no longer the main creator of childhood couch potatoes.

Traditional television viewing has decreased over the past 10 years, while time spent with other screen-based devices has surged, the researchers found.

"Although kids seem to be spending less time watching television, they're still viewing TV content. They're just doing it on these new devices," Barnett explained. "It means they are still sedentary with these other types of screen-based recreational devices."

Kids are being exposed to screens at an incredibly young age, the researchers discovered. One recent study found that average daily television time among children under 2 ranged from a half-hour to more than three hours.

"That's shocking to me," said Dr. Martha Gulati, cardiology division chief for the University of Arizona College of Medicine-Phoenix. "I don't know if the screen had become their babysitter, but I don't think that is what children are really meant to interact with."

Further, there's still a link between time spent on a screen and the likelihood of excess weight.

The percentage of kids who spend more than two hours a day with a screen has increased by about a third in recent years, Barnett said -- from about 16.4 percent in 2003 to 21.7 percent in 2007.

It makes sense that screen time will be sedentary, said Gulati, who is editor-in-chief of CardioSmart.org, the American College of Cardiology's patient information website.

"If they're texting their friends, most of the time they're sitting down to text. If they're on Instagram or Snapchat or whatever, they're usually sitting," she said.

But Barnett and Gulati both admit that limiting screen time to two hours will be tough for most parents.

"Two hours is a great goal," Gulati said. "I don't think people should be sitting for so much of their time, either children or adults. Realistically, I think that's going to be a very hard goal for parents to hold their children to."

Barnett suggested that parents who want to limit their kids' screen time might do better to focus on other things that the children could be doing.

"Getting face-to-face time, getting time outdoors, making sure there are pursuits that are free of devices -- I think that will necessarily reduce and control screen time," Barnett said.

Gulati added that parents can also help by setting a good example and limiting their own use of screen devices.

"If their parents go out for a walk every evening, children learn that is something you do as a family," she said. "If parents are watching TV all the time, children tend to watch TV as well."

The heart association recommends banning screen devices from the dinner table and from bedrooms. Other possible ideas include:

  • Setting aside time for physical activity as a family, preferably on a daily basis.
  • Planning TV watching in advance, picking select shows you want to watch and avoiding channel-surfing.
  • Avoiding use of TV or devices as a reward or a punishment for good or bad behavior.

The review was published online Aug. 6 in the American Heart Association journal Circulation.

More information

The American Heart Association has more about limiting screen time.