Summary: The latest data show continued increases in rates of childhood obesity. For example, obesity rates for children 6 to 11 years old are estimated to have increased from 15.1 to 18.8 percent between 1999 and 2004. The Department of Health and Human Services estimates that 20 percent of children and youth in the United States will be obese by 2010. There are numerous negative health outcomes and financial consequences related to childhood obesity. Researchers have found that childhood obesity is associated with a number of disorders including hypertension, insulin resistance, sleep apnea, menstrual abnormalities, and orthopedic problems. According to one estimate, insured children treated for obesity are approximately three times more expensive for the health system than the average insured child. Some researchers have suggested that childhood obesity is largely the result of a decline in regular physical activity. In our October 2005 report, we surveyed experts on the key strategies to include in the design or implementation of a program to prevent or reduce childhood obesity. The program strategy identified by experts as most important was "increasing physical activity." Congress asked us to provide information on the factors affecting physical activity in children.
Obesity results from an imbalance between the amount of energy consumed and the amount of energy expended. While there are many elements that affect the energy balance (for example, genetics, growth, and physiology), children and their parents can influence both energy consumed through diet and energy expended through physical activity. In summary, the articles we reviewed identified a number of factors affecting levels of physical activity in children. We categorized the factors presented in the articles we reviewed into three groups--demographic factors, cognitive and behavioral factors, and community factors. Demographic factors include socioeconomic status and race. Cognitive and behavioral factors include attitudes, beliefs, and perceptions and sedentary behaviors. Community factors include the built environment and school-based physical activity. The articles and additional materials we reviewed identified additional research needs, such as using objective measures of physical activity and sedentary time. The body of research we examined suggests that multiple factors that affect physical activity among children may contribute to childhood obesity.
