TORONTO -- When it comes to the risk of heart disease in children, too many hours spent in front of TV, computer and video game screens is worse than other sedentary time like reading a book, a new Canadian study suggests.

Members of TEAM PRODIGY included researchers from the University of Ottawa, Universite de Montreal, Concordia University, Universite Laval and McGill University. The inter-university research team conducted a cross-sectional study of more than 500 white children between the ages of eight and 10 with at least one obese biological parent.

Participants wore accelerometers designed to provide an accurate measure of physical activity levels over the course of seven days. Daily screen time was self-reported over the course of a week, and food intake was recorded for one weekend day and two weekdays, said first author Jean-Philippe Chaput, a researcher at the Children's Hospital of Eastern Ontario Research Institute.

The study showed a negative association between screen time and the heart health of kids.

For example, the study found screen time was linked to lower levels of high-density lipoprotein (HDL) cholesterol -- known as or "good" cholesterol -- which seems to help protect against heart disease.

"We know that when we engage in screen time, we eat more. So this excess caloric consumption with screen time is probably a key explanation here," said Chaput, a professor in the department of pediatrics at the University of Ottawa.

"It's well known that watching TV stimulates food intake. That's the same for video game playing and using laptops and so on. So, the fact that we eat more when we engage in screen time can lead to health problems down the road as opposed to just reading a book for pleasure or relaxing on the couch without screens. It seems to be better probably because we eat less."

In the study, screen time represented 55 per cent of the kids' sedentary activities, which involve little physical movement and a low expenditure of energy. Researchers found 40 per cent of kids met the guidelines of screen time use, which recommends two hours or less of screen time daily.

Chaput said study participants who had more than two hours of screen time daily consumed more calories than kids who met the guidelines.

Canadian guidelines recommend children and youth get at least 60 minutes of moderate- to vigorous-intensity physical activity daily. Walking quickly, skating and bike riding are examples of moderate aerobic activities, while running, basketball and soccer are examples of vigorous-intensity activities. But among study participants, only five per cent of kids met the recommended targets, said Chaput.

In order to encourage healthier habits among kids, Chaput said parents have to be leaders in modelling better behaviour.

"To have more phys ed and so on, it works well in the school setting; but when those kids go home and the parents eat pizza and watch TV, it doesn't work," he said.

"We'll never be able to address pediatric obesity if we don't start with their parents. So it seems maybe odd to hear that to solve a problem in kids we don't target kids. No, we target the whole family," he added.