The cliché of the couch potato has been confirmed by a unique study establishing a link between mind-numbing television and the elimination of satiation cues in children.
A group of boys who watched The Simpsons while eating a pizza lunch consumed 228 more calories - that's a piece and a half more of three-cheese pizza - than the youngsters who did not.
"The television distracts kids from recognizing satiety and satiation signals," said Nick Bellissimo, a scholar in clinical nutrition. "It's a no-brainer, but this is the first study to demonstrate the effect of television on overeating, and we had to prove the obvious."
Prof. Bellissimo, an assistant professor at Mount Saint Vincent University in Halifax, has spent the past decade studying the underlying roots of the obesity epidemic in children, with his former professor Harvey Anderson, director of the food safety, nutrition and regulatory affairs program at the University of Toronto's faculty of medicine.
They want to determine how children can stay at a healthy weight by looking at how appetite, satiety signals and food regulation interact with physiology and environment. "We want to understand these factors so we can prevent kids from getting fat," Prof. Bellissimo said.
For the TV and gluttony experiment, 14 boys participated on four different consecutive Saturdays. Some of the boys, aged 9 to 14, ate the pizza lunch while watching two episodes of The Simpsons , while others ate without the TV on.
Some were given a sweet snack (water with glucose) before the pizza lunch.
The researchers found that those who watched TV kept eating past their satiation point, including those who had had the snack beforehand.
Those who didn't watch TV ate less. And those who didn't watch TV and who received a prelunch snack ate the least of all. This finding shows that snacks between meals help control a child's appetite - but only if the TV is off so they can feel the effect of the snack.
Canadian and American children spend between 14 and 20 hours a week watching television - a habit that has been associated with the rise in obesity among children. But researchers wanted to measure the direct link.
"It's important to note that this isn't mindless eating, like munching on popcorn at a movie," Prof. Anderson said. "This was eating a full meal in front of the TV and not feeling full. So it supports the notion that a family dinner with the television off helps children have healthier body weights."
Results of the study, highlighted in a recent University of Toronto newsletter, was first published in 2007 in Pediatric Research
The study's findings resonate with the experience of Adrianna Borkowski, a Toronto mother and educator. She guiltily admits to turning on the television set in her living room so her two children, aged 7 and 4, can take in their favourite program, The Fairly OddParents , while she cooks. Sometimes it stays on during dinner.
Her husband, a consultant, travels during the week, and she is often on her own: "The TV is my helping hand," she says, laughing. "I do prioritize and really want my kids to eat a good quantity of nutritious food, so I use the TV to help me get in a spoonful or two of broccoli."
Ms. Borkowski notices her son does eat more when the television is on - but he is not overweight, so it's not a problem. "As my kids get older, the TV may not be the best tool if it desensitizes them to the trigger of feeling full," she says.
Another Toronto mother says her three children eat less, not more, if the TV set is on during supper. Some preschoolers will consume less food in this setting because they become distracted, the researchers say. As well, older children may control their food intake because their parents have taught them to restrict calories.
Still, the experts' advice is: Don't install a television in your kitchen, and if you do, turn it off during meals.