According to a 2004 report by the Institute of Medicine Committee on Prevention of Obesity in Children and Youth, approximately 9 million American children over 6 years of age are considered obese--that is, they have a body mass index (BMI) equal to or greater than the 95th percentile as calculated by the Centers for Disease Control and Prevention (CDC). Yet most experts believe the 9 million figure is minimal. Rates of obesity also are much higher among some populations and in certain geographic areas. And the prevalence of childhood obesity is growing exponentially. In the past three decades, it has more than doubled in children aged 2-5 and 12-19, and more than tripled in children aged 6-11.

There is currently a wide variety of activity at all levels aimed at reducing the epidemic of childhood obesity, as shown by the gathering of more than 700 experts from many fields in early June 2005 for Environmental Solutions to Obesity in America's Youth, a conference sponsored by the NIEHS. The meeting followed up on the success of a similar event held in 2004, which was aimed primarily at identifying research opportunities and needs to help design a research agenda related to environment and obesity. This year, the focus was on solutions.

"The goal of the conference was to try to identify the successful environmental interventions that have been developed across the country, and then to disseminate them more broadly," said primary organizer Allen Dearry, NIEHS associate director for research coordination, planning, and translation. "The major accomplishment was to bring together a very interdisciplinary group of experts in environmental health sciences, and in fields like planning and transportation, and policy makers to work together and think collaboratively, and to be able to define what makes one of these successful environmental interventions work."

The conference was supported in part by the Robert Wood Johnson Foundation. The planning committee included representatives from the NIH, the CDC, and the U.S. Department of Transportation, as well as from state and local health departments, academia, and the American Planning Association. Keynote speakers included NIEHS director David Schwartz, U.S. surgeon general Richard Carmona, CDC director Julie Gerberding, former National Football League star Lynn Swann (who is now the chairman of the President's Council on Physical Fitness and Sports), U.S. Department of Health and Human Services secretary Michael Leavitt, and Arkansas governor Mike Huckabee.

Pinpointing the Factors

As several participants pointed out, human genetics and biology don't change quickly enough to account for spiking obesity rates of the past 30 years, so a complex array of environmental factors that influence individual behavior is clearly at the root of the epidemic, in both children and adults. At a press conference announcing the forthcoming awarding of $5 million in NIH/CDC research grants addressing obesity and the environment, Schwartz said that defining the interface between environmental components and individual choices will be crucial to building a solid evidence base to support and refine efforts to stem the obesity tide.

"There's a fine balance between the environment and the individual that allows some people to make the choice for a more active and healthier life, and others to continue to eat the wrong types of foods or not be involved in physical fitness programs," Schwartz said. "That balance is very difficult to understand, and that's the focus of this research program and this conference."

The stakes involved are high. Obesity greatly increases a child's risk in adulthood of developing and dying from serious chronic conditions such as cardiovascular disease, type 2 diabetes mellitus, and certain cancers. Further, many children already suffer from adverse health effects related to their obesity.

Hypertension, until recently virtually unseen in young people, now strikes an estimated 4.5% of obese school-age children. Type 2 diabetes, also once considered rare in youngsters, is now showing up more frequently (the CDC is currently investigating incidence and prevalence). In addition, obese youth often suffer from impaired quality of life, emotional effects such as poor self-image, elevated cholesterol, orthopedic conditions, liver diseases, sleep apnea, and metabolic syndrome (a cluster of disorders that increases risk of heart disease and diabetes), among other negative outcomes. If left unchecked, the public health burden of childhood obesity will only continue to increase.

Finding Common Ground

Speaker David McCarron described the work of Shaping America's Youth (SAY), a public-private partnership that recently conducted a national survey of programs directed at physical activity and nutrition in children. SAY has established a national registry of such initiatives and is now approaching 2,500 program entries, with overall expenditures estimated at $3.9-7.1 billion. SAY's mission is to define the scope of those efforts and to make its information widely accessible. The goal is to foster dialogue at the community level, and ultimately develop a national action plan to combat childhood obesity.

"People are committed, but the problem is [the effort to address childhood obesity is] not organized, it's not being sustained, it's probably not directed at the right age group, and we need to take this commitment and interest and really get it focused ... on the very youngest children and their families," said McCarron, who is executive director of SAY. "We have to get to common goals, common language, common standards." He added, "They'll be modified community by community, and for each family they may be different, but we have to get to some very fundamental messages."

SAY will be conducting a series of town hall meetings over the next year in Memphis, Dallas, Philadelphia, and several California cities to get feedback from demographically representative community members. "It's not so much about teaching them something," McCarron explained. "We need to hear at a local level from the communities and the families as to what they see the problem as, what the barriers are. Otherwise, whatever we come away with from these national meetings might be totally disconnected."

The local socioeconomic environment, with often profound disparities in physical and financial access to healthy foods and physical activity, may contribute to the obesity epidemic, particularly among minority groups, who tend to suffer even higher obesity rates than the general population. Adam Drewnowski, director of the Center for Public Health Nutrition at the University of Washington, addressed this concept and showed that in his area of Washington state, geographic information system mapping of the distribution of obesity rates demonstrated an association of higher obesity rates with lower socioeconomic status and limited access to healthy foods. Using that type of methodology to tease out associations at the local level will be critical to successfully combating the problem, Drewnowski said.

Growing Smarter

The effect of sprawling development on sprawling waistlines was a subject of particular scrutiny at the conference. Roland Sturm, a senior economist at RAND, presented data from his recent unpublished national study of the impact of suburban sprawl on the development of chronic health conditions, including obesity. He found that greater sprawl was associated with an increase in chronic health problems, with the strongest associations with heart disease, abdominal and digestive problems, migraines and headaches, arthritis and joint pain, and trouble breathing. The study also suggested a relation between sprawl, reduced walking, and higher BMI.

"Smart growth" may be one approach that can help reverse these trends. Former Maryland governor Parris N. Glendening, who is now president of the nonprofit Smart Growth Leadership Institute, believes that incorporating opportunities for physical activity into built environment design is an important part of the mix to fight childhood obesity. "If we continue to build environments that discourage physical activity, we're going to continue to contribute to the problem," he said.

The Smart Growth Leadership Institute urges policy makers to take a broader, more long-term view of the potential impact of their decisions regarding the built environment and health. Policy changes encouraging mixed-use zoning and actual mixed land use--such as the shift of funds to public transit, the creation of sidewalks and bicycle paths, and the preservation of open spaces--are critical to the smart growth concept.