The government is planning to tackle the growing obesity epidemic in Britain by broadening its plans for eco towns and turning them into healthy or fit towns, the Guardian can reveal.

The health secretary, Alan Johnson, is convinced that two great challenges facing Britain - climate change and obesity - are linked.

He believes it makes sense that 10 eco towns already being planned by the government should now be built and designed to confront the UK's obesity crisis, drawing on pioneering schemes already producing results in Australia, France and Finland.

Mr Johnson wants Britain to follow the example of 10 French towns which have focused on young children and seen substantial cuts in obesity. The initiatives in France led to the proportion of overweight boys aged seven to 12 falling from 19% to 10% and in the girls from 10% to 7%.

He is convinced only a comprehensive rather than the current fragmented approach will work.

Practical measures in new healthy towns being considered by ministers include:

· Regular weigh-ins for children starting as they leave primary school, including the recording of body mass indexes

· Increasing the number of cycle lanes

· Designing safe walking routes to schools and from suburbs into the centre

· Programmes in schools to inspire children to eat healthily, avoid fast food outlets, learn to cook and play sport from a young age

· Ensuring GP practices are on the high street so more people can use them

· Larger parks, modern playgrounds and improved leisure centres

Details of the policy emerged as an authoritative five-year cancer study yesterday warned that one third of cancers are linked to our diets and lack of exercise. The report from the World Cancer Research Fund says obesity is a major factor in cancer and people should fight to keep their weight down throughout their lives. "The most striking thing to emerge from the report is the importance of overweight and obesity," said Sir Michael Marmot, professor of epidemiology and public health at University College London and chair of the panel which reviewed 7,000 studies on causes of cancer.

Mr Johnson said: "International evidence and research shows that we need a large-scale approach across the whole community to help tackle obesity. As part of our commitment to provide new eco towns we are also considering making them healthy towns - through their layout, facilities and construction. If this works it could also apply to areas undergoing housing growth and renewal."

He added: "We have to look at ways of improving the built environment, doing more to help people make physical activity a normal part of everyday life."

Mr Johnson is leading a cross-government drive to put the eco towns concept at the cutting edge of the fight against obesity. Each new town is planned to house as many as 20,000 people. He has also been looking at tackling some of the least healthy cities in the north or London boroughs to see if progress can be made in redesigning existing towns.

Obesity is estimated to cost the UK £1bn a year and is projected to rise to £45bn by 2050.

Last month's influential report by government scientists Foresight suggested that on current trends about 60% of men, 50% of women and 25% of children in the UK would be obese by 2050.

The report suggested the baseline projections indicate that "left unchecked, the health costs associated with overweight and obesity will become insupportable". It also repeatedly argued that there was no single magic bullet, but instead required a comprehensive long-term strategy.