Parents are fooling themselves if they hope Nintendo's Wii active games console, which uses a wireless handheld controller to replicate athletic movement, will stop their youngster becoming obese, a study says.
Researchers in sport science at Liverpool John Moores University in northwestern England recruited six boys and five girls aged 13-15 years and fitted them with a monitoring device to calculate energy expenditure.
The teens played four games for 15 minutes.
One of the four games was Project Gotham Racing 3, played on the sedentary XBOX 350, made by Microsoft.
The three other games were sports bowling, tennis and boxing, played on Wii Sports, with a five-minute rest between sports.
In all, the children played on the consoles for one hour.
Energy expenditure using Wii was "significantly greater" -- 51 percent more -- than on the XBOX, the scientists found.
But this figure alone is misleading, as the total number of extra energy units burned using Wii amounted to only 60 calories per hour, or about a quarter of a Mars bar.
"In a typical week of computer play for these participants, active gaming rather than passive gaming would increase total energy expenditure by less than two percent," says the study.
Even though the amount is "trivial," it might still make a contribution to weight management, the study admits.
And it says, a game that prompts a teenager to practise basic motor control and fundamental movement skills is a plus.
"Given the current prevalence of childhood overweight and obesity, such positive behaviours should be encouraged," it says.
Even so, nothing is a substitute for getting out of the home and doing sport itself.
"The energy used when playing Wii Sports games was not of high enough intensity to contribute towards the recommended daily amount of exercise in children," say the authors.
The study is released on Friday by the weekly British Medical Journal, which carries it in its Saturday edition.