Couch potatoes are sowing the seeds for health problems in adult life

Teenagers canvassed said their parents' lifestyles are most to blame for their own lack of exercise.

A third cited their parents' hectic work lives as the cause of their own sedentary living.

"Contrary to popular belief Britain's teenagers don't necessarily want to spend their time slobbing on the sofa," said Bupa's assistant medical director Dr Paula Franklin.

"They'd like to be more active and, even more surprisingly, want to do so with their parents."

Dr Franklin warned that teenagers with sedentary lifestyles are risking their future health.

"Today's couch potatoes are likely to be tomorrow's sick adults," she added.

More than a third of the parents surveyed were unaware of the recommended activity levels for children.

According to health experts, children should do at least half an hour of physical activity a day.

Previous research has suggested that young couch potatoes are at risk of serious illnesses such as heart disease and diabetes, while inactivity can also lead to lower grades in their exams.

Teenagers also want more PE at school

In adults, according to Bupa, obesity is the UK's biggest cause of ill health and leads to 30,000 premature deaths a year.

Dr Franklin said: "In many families, both parents work giving them less free time to spend with their children than in the past.

"Unfortunately, most bad habits formed in childhood are hard to break. To get kids off the couch and into physical activity, they need inspiration from their parents."

However, children did not blame only their parents.

More than half of the teenagers questioned also said they would exercise more, given access to better sporting facilities.

And nearly a third blamed their schools, saying more PE would make them more active in general.