An hour spent playing video games may make teenage boys eat more over the rest of the day, a small study suggests.
The study, of 22 normal-weight teens, found that the boys ate a bigger lunch when they had a pre-meal video game, versus an hour spent relaxing. And they did not make up for the extra bites by burning more calories through gaming, or by eating less later in the day.
On average, the boys downed 163 calories more on the day when they played video games, researchers report in the American Journal of Clinical Nutrition.
Exactly what that means for video gamers' waistlines is unknown. But the findings add to studies that have linked kids' screen time - from TV and computers - to the odds of being overweight.
While those studies observed patterns, and do not prove cause-and-effect, the current study actually tested the idea that something about video-gaming itself might affect eating habits, explained lead researcher Jean-Philippe Chaput.
It's not clear why boys ate more on game day, according to Chaput, who researches obesity and lifestyle at the Children's Hospital of Eastern Ontario Research Institute in Ottawa, Canada.
"We didn't see an increase in hunger," he said, adding that neither the boys' self-ratings of hunger nor their levels of appetite hormones appeared to be affected by playing video games.
Instead, Chaput speculated that there is a subtle "mental-stress effect", and eating food may satisfy the brain's need for a "reward".
"And most of the food we'd want," Chaput said, "would be sugary and fatty".
He noted that in past research, he has found a similar effect of computer work on calorie intake.
For the current study, Chaput's team had the teenage boys come to a research lab on two separate days: on one morning, they played a soccer video game for an hour, followed by lunch; on another morning, they sat quietly for an hour before lunchtime.
The boys then went home and kept a record of what they ate for the rest of the day.
Overall, Chaput's team found, the teens spent more energy when they played video games than when relaxing. But their food intake more than compensated for the energy they burned that day, netting them an extra 163 calories.
There are still many questions - including whether findings from the research lab translate into the real world.
Chaput speculated that the number of extra calories could be even greater in real life, where kids often spend hours playing video games in a day, and may eat junk food while they play.
On the other hand, it's not clear if the extra calories seen in this study are an "acute effect" that would fade if someone played video games regularly, according to Chaput.
But if video games do regularly affect how kids eat, he said, it would be concerning. Even though an extra 163 calories "sounds minor", Chaput said, "if it is chronic, it could have a major effect over the years".
By comparison, a can of regular coca cola contains 90 calories.
For now, Chaput suggested that parents try to limit their kids' time in front of the TV and computer, and replace some of those sedentary hours with physical activity.
Experts generally recommend that children get no more than two hours of screen time per day. But research suggests that few kids meet that goal.
Chaput suggested that parents "act as role models" for their kids, and spend less time parked in front of the tube themselves. "Go outside and play with your kids," he advised.
Still, Chaput said he is not blaming video games for the childhood obesity epidemic. "Obesity prevention is complex. This is just one factor in the overall picture."
One question for future studies, he said, is what kind of effects "active" video games, like Wii games, might have on kids' calorie balance.
On the positive side, they get users to move and burn calories; but if they also encourage overeating as compared to old-fashioned exercise, like riding a bike, that would be a downside.