Watching television, even for just an hour a day, may boost the risk that young children will be overweight or obese, according to new research.
"Children who watch one to two hours of TV a day, as opposed to those who watch less, are more likely to be overweight and obese at kindergarten and first grade," said the study's lead author, Dr. Mark DeBoer, associate professor of pediatrics at the University of Virginia.
Previous research has linked children's television viewing with obesity and other problems. But the new study finds even less screen time may be enough to influence children's weights.
It's important to note, however, that the study wasn't designed to prove that watching TV actually caused children to become overweight or obese. It could only reveal an association between TV watching and a child's weight.
The study included data from the Early Childhood Longitudinal Survey of more than 11,000 children attending kindergarten in 2011-2012.
The database included the number of hours kids watched TV, how often they used computers and records of their height and weight. A year later, most of the children were evaluated again for these same factors.
On average, kindergartners watched about three hours of TV daily. Those who watched one to two hours of TV a day, or more than two, were more likely to be at unhealthy weights than those who watched less, DeBoer found.
"An hour is not that much time," he said. "In that sense, I was surprised."
Referring to those in kindergarten, DeBoer said, "children who watched one to two hours of television a day were 43 percent more likely to be overweight and 47 percent more likely to be obese compared to children who watched less than an hour."
The more they watched, the higher the likelihood, he found.
This was only TV screen time; no other screen activities were evaluated. No link was found between computer use and unhealthy weights.
Dr. William Muinos is a pediatric gastroenterologist and director of the weight management program at Nicklaus Children's Hospital in Miami. He said, "The numbers are pretty significant no matter how you look at it."
Muinos believes an hour a day or more of television viewing recorded by the parents of kids at unhealthy weights may reflect other unhealthy habits, such as an unhealthy diet or snacking.
"You are establishing behaviors early in life," he said.
The American Academy of Pediatrics (AAP) advises parents to avoid all screen time for children age 2 years and under, and to limit entertainment screen time for older children to less than one to two hours a day. DeBoer said it may be time for the AAP to reconsider that policy and lower it even more.
Parents can set standards, Muinos said. For instance, parents might say children can watch an hour of TV, but only after getting in exercise or activity time.
The study is scheduled to be presented Sunday at the Pediatric Academic Societies' annual meeting in San Diego. Research presented at medical meetings are typically viewed as preliminary until published in a peer-reviewed journal.