A senior play specialist has dismissed the Government's anti-obesity drive as a "quack remedy".
Rob Wheway, who has more than 30 years' experience advising councils on children's play, said the emphasis on diet, workouts and stomach-stapling is serving private business rather than the needs of pupils.
"Look at the list of people consulted over obesity, and many are associated with vested interests," he told The TES. "I am talking about providers of medical treatment, fitness regimes and diets."
The National Obesity Forum, which has been consulted by the Government over its new strategy, has partners including Roche, manufacturers of weight-loss drug Xenical, and diet-food companies Slim Fast Foods Ltd and Canderel.
But Dr Colin Waine, chair of the forum, refuted claims that their advice to government was tainted: "Our partners have never sought to influence us in any way and in fact have probably done more for the fight against obesity than many others." Large sponsors provided pound;20,000 to pound;30,000 a year in funding and attended conference and meetings, he said.
A spokesman for Roche said they followed "a strict code of practice" when lending to campaign groups and did not challenge their integrity. A Department of Health spokesman added that partnerships with private companies were a "vital" part of their work.
But Mr Wheway said: "Therapies won't help the majority of children. While there is little evidence to show children's calorific intake has increased, there is a great deal of evidence to show that play has decreased."
This could not be solved by blaming schools or introducing structured exercise, he said, but by making streets safer areas for children to play on. The distance children roam has shrunk to a ninth of what it was 25 years ago, while the proportion of children who walk to school unaccompanied has fallen from 80 per cent to less than 9 per cent since 1970.
Mr Wheway's comments were supported by organisations including the lottery-funded Play England.
Adrian Voce, its director, said: "Children are naturally active. All we need to look at is what's standing in their way."
It is not the first time that the received wisdom about obesity has been called into question. The International Association for the Study of Obesity dismissed gym workouts as "hopeless" for losing weight. And some studies suggest that children are actually eating more healthily than ever before.
Nicola Massey, head of St John and St James CofE primary school in east London, said children enjoyed the sociable side of exercise. "We've organised 'walking buses' to and from school, and the pupils love it," she said.