The "terrifying health consequences" of the UK's obesity epidemic were forcefully highlighted by leading doctors yesterday as they called for urgent action to tackle the problem.

Unless attitudes change, one in three adults will be obese by 2020 and more children will develop diabetes, they warn.

And last night, the academic who believes he could help teenagers get in trim called on the Government to fully fund so-called "fat camps".

Dr Paul Gately, the director of the UK's only camp for obese children, claims a 70 per cent success rate in weight reduction.

But because of lack of NHS funding the vast majority of campers have to find up to £2,200 for a six-week course which aims to make sport enjoyable and give children the skills to maintain weight loss.

Among a number of North-East youngsters to benefit from the camp is Colin Ord, 18, from Seaham, County Durham, who went from 33 stones to 25 stones.

But the NHS's reluctance to fund places means that hundreds of applicants have to be turned down.

It also means that tentative plans to found more camps - including one in the North-East - have had to be put on hold.

"We have had a lot of talk and very little action from the NHS over obesity," said Dr Gately, who is a principal lecturer in sport, exercise and health at Leeds Metropolitan University.

He described efforts by the Government to tackle obesity as, "like trying to stop a supertanker with a water pistol", and urged the NHS to take the Leeds experiment seriously.

The joint report from the Royal College of Physicians, the Faculty of Public Health and the Royal College of Paediatrics and Child Heath sounded alarm bells over the nation's weight problems.

More than half of the UK is either overweight or obese - in 2002 the figures stood at 70 per cent of men and 63 per cent of women.

Obesity among children aged two to four almost doubled between 1989 and 1998, from five to nine per cent.

Professor Carol Black, president of the Royal College of Physicians, said it was important to take action from the highest level of Government down to families and individuals. She also called for a national strategy to combat obesity cutting across health, transport, agriculture, leisure and the food industry.

The college also called for a sustained public education campaign to promote healthy eating and an active lifestyle.

A spokesman for the Department of Health said the issue of "fat camps" could be looked at as part of the debate about the best way to tackle obesity. He stressed that efforts were being made to promote exercise and healthy eating in schools.