A new study has researchers calling for stricter recommendations on screen time for kids following evidence that suggests watching only an hour of TV a day is linked to an unhealthy weight. 

Researchers from the University of Virginia analyzed data from more than 11,000 children, and found kindergartners and first graders who watched an hour of TV daily were more likely to be overweight or obese than children who watched for less than 60 minutes.

The childhood obesity epidemic in the United States has been a hot topic in recent years, taking center stage with First Lady Michelle Obama’s “Let’s Move” campaign. According to the Centers for Disease Control and Prevention (CDC), childhood obesity has more than doubled in children and quadrupled in adolescents in the past 30 years. The CDC estimated that in 2012, the most recent data available, more than one-third of children and adolescents were overweight or obese.

Previous research has shown a link between obesity and screen time in children, but statistics have not shown such a short amount of time can have such a significant effect on weight gain.

Study authors drew data from the Early Childhood Longitudinal Survey (CLS), from the National Center for Education Statistics. That data included three longitudinal studies that examine child development, school readiness and early-school experiences.  Also included lifestyle factors, such as the number of hours of TV that children watched and how often they used computers, and children's weight and height.

Researchers recorded the same information a year later, and found both kindergartners and first-graders who watched one hour of TV or more per day had significantly higher body mass indexes— and were up to 60 percent more likely to be overweight and up to 73 percent more likely to be obese than children— who watched less than 60 minutes a day.

Study author Dr. Mark D. DeBoer, associate professor of pediatrics in the division of pediatric endocrinology at the University of Virginia, said computer use was not associated with higher weight in the study.

“High amounts of computer use would be expected to be associated with less physical activity but may not lower energy expenditure quite as much as TV viewing,” DeBoer told FoxNews.com. He added that children may be exposed to fewer unhealthy food commercials on the Internet compared with TV, and that using a computer provides less of an opportunity for snacking.

Study results showed the average U.S. kindergartener watches 3.3 hours of TV per day. The American Academy of Pediatrics (AAP) recommends limiting children and teens to fewer than two hours of daily screen time. But according to DeBoer, his research proves the recommendations are not strict enough.

“We hope that the American Association of Pediatrics consider reducing its allowed TV viewing to one hour daily for young children and recommend that parents replace their children's TV viewing time with opportunities for physical activity and educational activities,” he said.

DeBoer and his team plan to continue studying this group of children to learn whether their gain sustains over a number of years, and whether there may be evidence that children who lower their TV viewing time can reverse some of the associated unhealthy weight gain.

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