Children are leading increasingly inactive lives that could hold the seeds of a future epidemic of obesity, scientists have said.
The warning follows a study of 38 Oxford secondary school pupils aged 10-13. Most fell short of the Department of Health's recommended energy expenditure. At weekends, some were so inactive that their physical activity levels were the same as bed-ridden hospital patients.
One girl spent days lounging in bed - eating, watching television and playing video games - and got up only to use the toilet.
Although most pupils were more active, the researchers concluded that only a handful engaged in anything more than light exercise. On average, boys seemed to be worse than girls when it came to expending energy.
Inactive children risk becoming overweight and, as adults, obese. Obesity brings a host of health problems such as diabetes and heart disease.
The research was led by Jeya Henry, professor of human nutrition at Oxford Brookes University. He said: "Our childhood experience was of running around like headless chickens. But now children spend more time playing computer games and watching television."
He said that even if parents were reluctant to allow children out to play sports such as football, kids could still get a lot of exercise in the home as well as at school. "We are not doing as much as we should on obesity in this country. Without concerted action, this is a problem that is going to get worse," he said.
Experts increasingly fear that obesity is rising to epidemic proportions, with more than 300 million people affected worldwide. Some believe the problem could eclipse malnutrition and infectious diseases as the biggest cause of ill health.
The Oxford Brookes team is conducting a child lifestyle pilot study for the Food Standards Agency. This will help guide physical activity and healthy eating programmes for primary school children.
A spokesman for the DoH said steps were being taken to improve the diet and increase the physical activity of youngsters.