Children watching as little as one hour of television a day can increase the risk of childhood obesity, according to a recent study.

Researchers at the University of Virginia found that kindergartners and first-graders who watched as little as one hour of television a day were more likely to be overweight or obese compared to those who watched TV for less than 60 minutes each day

"Given overwhelming evidence connecting the amount of time TV viewing and unhealthy weight, pediatricians and parents should attempt to restrict childhood TV viewing," study author Mark D. DeBoer said in a statement.

Previous studies have shown that children who watch a lot of TV are at risk for being overweight. However, studies have not looked specifically at the link between TV watching and obesity among kindergartners.

For the study, researchers collected and analyzed data from the Early Childhood Longitudinal Survey of more than 11,000 children who were in kindergarten during the 2011-2012 school year. They took note of the number of hours of television children watched on weekdays and weekends, and how often they used computers. In addition, children's weight and height were measured.

A year later, 10,853 of the children's height and weight were measured, and parents again were asked about their child's TV habits.

Results showed that U.S. kindergartners watched an average of 3.3 hours of TV a day. Both kindergartners and first-graders who watched one to two hours or more than two hours daily had significantly higher body mass indexes than those who watched less than 30 minutes or 30-60 minutes a day, even after adjusting for socioeconomic status, race/ethnicity and computer use.

In both kindergarten and first grade, children viewing as little as one hour of TV daily were 50 to 60 percent more likely to be overweight and 58 to 73 percent more likely to be obese compared to those watching less than an hour. Computer use, however, was not associated with higher weight.

Furthermore, children who watched one hour or more of TV daily were 39 percent more likely to become overweight and 86 percent more likely to become obese between kindergarten and first grade.

The American Academy of Pediatrics (AAP) recommends limiting children and teens to less than two hours of screen time each day. DeBoer, however, said even that might be too much.

"Given the data presented in this study, the AAP may wish to lower its recommended TV viewing allowances," he said.

The findings will be presented Sunday, April 26 at the Pediatric Academic Societies (PAS) annual meeting in San Diego.