Americans need to think about how to redesign schools, workplaces and communities to encourage exercise and healthy eating--otherwise we'll just keep getting heavier. That's the message attendees took home from a May 24-26 conference on obesity and the built environment.

The conference, sponsored by the National Institute of Environmental Health Sciences, brought together more than 500 urban planners, public health experts, psychologists and others to discuss research needs and highlight successful intervention strategies.

A complex mixture of genetics and environment underlies our national weight gain--nearly two-thirds of Americans are overweight and one in three is obese, according to the National Institutes of Health (NIH)--and the conference focused on environmental contributors.

"We've developed the ability to change our environment at speeds that evolution cannot adapt to," said NIH Director Elias Zerhouni, MD, in the conference opening address.

Humans evolved to crave sugar and fat at a time when food was scarce, and we needed to be physically active to survive, Zerhouni explained. But in the world we inhabit now--rife with cheap, high-calorie food, desk jobs and hours-long commutes--those same cravings are making us fat.

Three psychologists joined dozens of other speakers at the conference to discuss strategies to change that, including developing exercise-friendly communities and making healthy food more available to all socioeconomic groups.

  • James Hill, PhD, founded an initiative called America on the Move to help people take small steps to avoid weight gain. America on the Move staff work with schools, workplaces and communities to develop programs that encourage people to walk 2,000 extra steps per day (about one mile) and eat 100 fewer calories per day.

"The average adult gains one to two pounds each year," said Hill, also the director of the Center for Human Nutrition at the University of Colorado Health Sciences Center and a physiological psychologist. "So the first goal has to be no more weight gain."

The 100-calorie reduction and 2,000-step addition to a person's daily routine should be enough to do just that.

"The key is to make small, achievable changes," Hill said.

America on the Move also works with housing developers to design more walkable communities--those with essential services like grocery stores within walking distance of homes. Hill and his team are helping to plan two new neighborhoods in the Denver area that will encourage walking and discourage driving using sidewalks, open space and pedestrian-accessible services.

  • Adam Drewnowski, PhD, studies the impact of foods' taste, cost and convenience on people's eating habits. At the conference, he spoke about the link between poverty and obesity.

The most obese states in the country also tend to be the poorest, said Drewnowski, a psychologist and the director of the Center for Public Health Nutrition at the University of Washington. The trend is evident on a smaller scale too: His research shows that obesity rates in poorer neighborhoods in Seattle are more than twice as high as those in wealthier neighborhoods.

The main reason for this disparity, Drewnowski said, is the low price of energy-dense foods. At American retail prices, for example, a consumer can get upwards of 1,000 calories per dollar from refined sugar. In contrast, an apple would provide only about 150 calories for the same price.

"Obesity is largely a problem of minorities and the working poor," he said. "We need to be sensitive that our solutions are not overly middle-class."

  • James Sallis, PhD, studies how the environments people live in influence their physical activity levels. For example, he's working on a project to examine residents' physical activity in four kinds of neighborhoods--those with high and low walkability, and those with high and low income levels--to see how those factors interact.

In addition to conducting his own research, Sallis helps other researchers gain funding as a director of the Active Living Research program, which is sponsored by the Robert Wood Johnson Foundation. The program funds research to study how environments and policies affect people's physical activity.

Earlier studies provide some general statistics: For example, 43 percent of people with safe places to walk within 10 minutes of their home met recommended activity levels, but only 27 percent of people without safe places to walk did. Now, Active Living Research is trying to build on that earlier research by finding out what specific details make some parks, neighborhoods and communities more conducive to activity than others.

"We need to leave the easy solutions [to the obesity epidemic] like just trying to educate individuals, and move to harder, higher-level policy solutions," Sallis said.