Health campaigners are urging urbanites to get streetwise and walk. Credit: © Punchstock

Public-health officials in the United States are proposing a new and drastic way to fight the onslaught of obesity: they want to redesign entire towns to make them exercise-friendly.

The suggestion comes amid increasing concern over the population's growing girth: around two-thirds of adult Americans are now classed as overweight or obese.

Many recent health campaigns urge people to walk, cycle or be otherwise active during the day. But that's easier said than done; in a typical US housing estate, the only way to reach workplaces, shops and schools is by car. Many streets lack pavements, and cycle paths are virtually unheard of.

To really fight the flab, US public-health officials are now realizing that they may have to change the entire layout of towns. The suburban mansion and sport-utility vehicle(SUV) may fulfil the American dream, they say, but it is taking an unforeseen toll on health.

One study from last year compared the health of people living in foot-friendly city areas with that of those dwelling in sprawling, car-dependent suburbs. People's average weight and level of hypertension rose along with the degree of sprawl.

And although purpose-built recreation centres and parks are well intentioned, experts say that only a fraction of people make the effort to use them. "That's where we've been going wrong in the past," says Rich Killingsworth, who directs Active Living by Design, an organization that promotes physical activity and is part of the University of North Carolina at Chapel Hill.

To tackle the problem, obesity experts, town planners and architects, among others, came together in Washington DC last week to focus on obesity and the built environment. Delegates were queuing up to attend the conference, says organizer Allen Dearry of the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina. "It struck a nerve," he says.

Slimline design

One seemingly obvious way to eliminate people's dependence on cars is to design communities in which shops, schools and workplaces are within walking distance of homes. One community called Southern Village in North Carolina, for example, is built to be more like a traditional neighbourhood with pavements, trails and parks aplenty.

Such solutions may seem intuitive, but researchers point out that there is no evidence that living in such communities actually stops people piling on the pounds. Concerns about traffic, crime or other social factors can prevent people from venturing outdoors. "It's not always the case that building it means people will use it," says Dearry.

There are several other obstacles to overcome before communities can be built or revamped with exercise in mind. At present, for instance, many US local authorities have zoning regulations that were originally designed to get people out of polluted or unsafe cities into the countryside, and these prohibit the construction of houses and businesses next door to one another.

Some commentators point out that the house-building, motor and road industries are not used to considering public health in their plans, and are somewhat slow to change. "They keep building communities as they've done traditionally," says Dearry.

Dearry hopes that more studies showing the effectiveness of exercise-friendly communities will help to convince policy-makers and industries of the importance of health. The health institute has $3 million of funding for such research next year and hopes to offer more in future years, he says.