we carefully evaluate our programs and policies in terms of efficacy, effectiveness, and cost utility, we can devise new and innovative approaches based on our experience, discard those that are less useful, promote those that work, and follow through accordingly.

Childhood obesity is complex because it has biological, behavioral, social, economic, environmental, and cultural causes, which collectively have created over decades an adverse environment for maintaining a healthy weight. This environment is characterized by:

• Urban and suburban designs that discourage walking and other physical activities

• Pressures on families to minimize food costs and acquisition and preparation time, resulting in frequent consumption of energy-dense convenience foods that are high in calories and fat

• Reduced access and affordability in some communities to fruits, vegetables, and other nutritious foods

• Decreased opportunities for physical activity at school and after school, and reduced walking or biking to and from school

• Competition for leisure time that was once spent playing outdoors with sedentary screen time—including watching television or playing computer and video games.

The result is that obesity from unhealthful eating and inactivity has rapidly become the social norm in many communities across America. In that respect, the nation is moving away from—instead of toward—the “healthy people in healthy communities” vision of Healthy People 2010. Although assigning blame for this situation may be easy, it is unlikely to be accurate or productive. In general, the average person does not make the conscious choice to become obese, despite the adverse health and social consequences. No industry aims to promote weight gain among its customers. Nonetheless, excess weight is gained slowly over time as companies develop and market foods and beverages to maximize revenues; community zoning and street-design decisions are influenced by numerous social and financial pressures; schools face scheduling constraints in fitting everything into the school day while facing the reality of budgetary limits; and individuals make small but cumulative behavioral decisions daily about eating and physical activity in the obesogenic environment that surrounds them.

Now that the nation has begun to realize the significant health, psychological, and societal costs of an unhealthy weight, it is time to re-examine its way of thinking and revise the social norms that are now accepted. This process should span virtually the entire spectrum of society, from corporate board rooms to federal agencies, from elected officials to health insurers and employee unions, from health and medical professionals to teachers