Researchers from Stanford University, USA, have found that children are less likely to put on weight if they stop watching television.

Simply reaching for the off switch seems to be good enough, the children did not need to change their diet or increase the amount they exercise.

The study of 192 chidren aged eight and nine found that those who cut the number of hours spent watching television gained nearly two pounds (0.91 kg) less over a one-year period than those who did not change their television diet.

Lead researcher and paediatrician Dr Thomas Robinson said the findings are important because they show that weight loss can be attributed to solely a reduction in television viewing and not any other activity.

He said: "One of the things that makes this study unique was that it focused specifically on reducing TV, videotape and video-game viewing without promoting any other activities as substitutes."

Obesity rates have jumped

On average, American children spend more than four hours per day watching television and videos or playing video games, and rates of childhood obesity have doubled over the past 20 years.

In the study, presented this week to the Paediatric Academic Societies' annual meeting in San Francisco, the researchers persuaded about 100 of the students to reduce their television viewing by up to one-third.

Children watching fewer hours of television showed a significantly smaller increase in waist size and had less body fat than other students who continued their normal television viewing, even though neither group ate a special diet or took part in any extra exercise.

Dr Robinson said one explanation for the weight loss could be the children unglued from the television may simply have been moving around more and burning off calories.

Another reason might be due to eating fewer meals in front of the television.