Four in five parents do not care whether their child gets enough exercise despite soaring childhood obesity rates, a survey shows.
An hour of activity a day is recommended
The British Heart Foundation says this apathy to 'couch potato' lifestyles could mean today's young people become tomorrow's heart attack patients.
The research comes as the government is publishing its white paper on public health.
Obesity is tipped to be one of the main priorities of the white paper.
More than 22 million children under five years old are obese or overweight, according to the World Health Organization.
Among youngsters aged two to four, obesity almost doubled between 1989 and 1998 from 5% to 9%.
Among those aged six to 15, obesity rates trebled from 5% to 16% between 1990 and 2001.
If current trends continue, experts believe at least a third of adults will be obese by 2020.
The BHF survey of nearly 500 parents and more than 1,000 children aged seven to 16 found only a quarter of young people were doing the recommended hour of activity every day.
Only a fifth of the parents were concerned by this.
As part of its Well Fit! campaign the BHF is encouraging parents to help their children become more active.
It believes parents are key to tackling the obesity problem.
Almost half of the parents said they believed they did more exercise as a child than their own kids do now.
Eight out of ten parents felt they should be responsible for ensuring their kids get enough exercise.
Deborah Allen of the British Heart Foundation, said: "Every parent has a key role to play.
"Exercise is fun as well as being vital for a healthy heart and we want to help parents get their children Well Fit!"
More information is available on the BHF website.
Dr David Haslam, chair of the National Obesity Forum, said: "I'm staggered by the statistics.
"Activity is essential. It's protection not just against obesity but protection against heart disease and cancers in later life.
"The problem is partly one of motivation and partly one of education.
These four out of five mothers and fathers do not love little Jonnie any less than the one out of five.
"It's just they are not aware of the trouble they are causing for their child by not ensuring an active lifestyle."