Leading doctors say immediate action is needed to tackle the rise in obesity.
Increasing numbers of people are overweight
Experts from three medical royal colleges say the government, the food industry and the medical profession all need to address the issue.
They warn that if current trends continue, at least a third of adults a fifth of boys and a third of girls will be obese by 2020.
Obesity causes about 30,000 deaths a year in the UK, through problems such as heart disease, stroke and diabetes.
The Royal College of Physicians, the Faculty of Public Health and the Royal College of Paediatrics and Child Health said action was needed, from Cabinet level down, to ensure healthy living was promoted in schools and hospitals.
In a joint report, they say the government should launch a campaign to educate the public about the benefits of healthy eating and being active.
And they say the food industry and the Food Standards Agency should work together to produce and promote healthier foods.
The report also calls for health professionals to be trained in how best to prevent and manage obesity, and for more research into why it is still a problem.
Professor Sian Griffiths, president of the Faculty of Public Health, told BBC News Online: "We need action, not just discussion."
She said some initiatives had already been introduced - such as introducing fruit-filled vending machines in some schools, but obesity was still on the increase.
"There has been a tendency to blame individuals," she added.
UK'S BATTLE WITH THE BULGE
23% of women and 21% of men were obese in 2001
Those figures were 8% and 6% in 1980
Weight problems cost the NHS £500m a year
16% of six to 15 year olds were obese in 2001
In 1990, that figure was 5%
Obesity in pre-school children was 9% in 1998
"We have to avoid that as there may be factors that are not their fault, such as children not having somewhere safe to play."
Professor Peter Kopelman, who chaired the working party which compiled the report, told BBC Breakfast there were serious concerns children were storing up medical problems for the future.
"It's important for our children and their children that we tackle the obesity problem because if we don't there's going to be a disaster further down the line."
But Conservative MP Ann Widdecombe, who appeared on the television programme Celebrity Fit Club and lost 36lbs in a year, said there needed to be better sense of proportion.
"If you look around the average playground there may be one or two children who are Billy Bunters but the overwhelming majority will be tearing around screaming, healthy and enjoying themselves.
"We are all being encouraged to watch every pound.
"People who look perfectly normal and are healthy worry themselves into a passion over putting on half a stone over Christmas."
Health Secretary John Reid said: "The authors are right to highlight the problem of increasing obesity, particularly among our young people.
"We need to find the right balance between so-called 'nannying' and simply washing our hands of our people's health."
"That's why we have announced a consultation which will lead to a White Paper later in the year setting out future policy on public health."