'Lifestyle revolution' promised

Supermarkets and gyms are among more than 12,000 businesses, charities and local groups who have agreed to promote healthy living as part of the Government's Change4Life programme.

It is designed to halt a weight problem epidemic that threatens to leave 90% of youngsters at risk of obesity-induced illness and cost the NHS £50 billion a year by 2050.

But research for the Department of Health found most parents were blind to the reality, with almost nine out of ten failing to recognise that their children were overweight or obese. "The message that we received from parents was clear - we recognise that obesity is a big problem, but it's not our problem," Mr Johnson said.

"The aim of Change4Life is to help parents understand that obesity is a problem for all of us and that it causes severe illnesses and premature death. Finger wagging and lecturing won't work, that's why Change4Life is designed to be supportive and helpful."

Mr Johnson hopes to persuade the whole country - from multinational firms to grassroots community groups - to "help mums, dads and families eat well, move more and live longer". Local initiatives such as healthy food promotions, walking campaigns, cycling groups and free swimming for the under 16s and over 60s will be backed up by a £75 million taxpayer-funded advertising campaign.

The Department of Health said it had already struck "unprecedented" agreements with supermarkets Tesco and Asda to offer cut-price healthy food and run in-store promotions. ITV is to run a series of programmes tracking viewers' efforts to switch to healthier lifestyles; food giant Kellogg's is supporting breakfast clubs in poor areas and sponsoring swimming schemes; and drinks manufacturer PepsiCo will use sports stars to advertise the benefits of "active play", it said.

The Fitness Industry Association will also offer free trial gym memberships next summer but Mr Johnson appealed to every company boss in the country to take part.

"Obesity is the biggest public health challenge the country faces. If we don't take action now we will condemn our children to reduced life expectancy. That's why we are aiming to create a lifestyle revolution that will help families to eat well, move more and live longer. We can't start a revolution on our own - we need everyone from grassroots community clubs to multinational companies to join us.

"Ten million people visit their corner shops every day and 36 million shop at Asda and Tesco each week - the fact that grocers and supermarkets are on board means we can really influence what goes into our shopping trolleys. Obesity affects us all so everyone must get involved."