Cars should be banned from roads around schools to make families walk in a bid to tackle the spiralling problem of obesity, a report claims.
The Institute for European Environmental Policy (IEEP) said 38% of all journeys under two miles - which could be covered in 30 minutes with a brisk walk - are now taken by car.
But if a typical adult walked an hour more a week, it could stop them gaining two stones over a decade and make a major contribution to halting the obesity crisis, it added.
The IEEP report also reveals that changing people's behaviour will be a massive effort costing millions of pounds, but a first step should see cars banned from schools or local shops which could save the NHS cash in the long run.
Britain has one of the fastest growing rates of obesity in the world, with 23.6% of men and 23.8% of women having a body mass index (BMI) of 30 or more in 2006.
The report's lead author, Dr Adrian Davis, said: "The substitution of car use for walking is a major contributor to the steep rise in obesity, as walking is the most obvious way for most people to burn calories.
"A small daily reduction in walking over a decade or more has a profound and damaging impact on body weight."
"I have recently started a new job which is 20 minutes walk away from where I live. I have started walking to work most days and am feeling much fitter for it after only a few weeks. I am trying to encourage my colleagues as well as my patients to do the same!" - Name and address supplied
"I would love to be able to walk to work but as a community nurse I have to travel to different clinics and carry lots of equipment. I encourage my patients to walk as much as possible" - Mireille Hay, specialist nurse, Glasgow