Over the past three decades, obesity rates have more than doubled among adults, and tripled among children and adolescents. In 2011-2012, about 32% of U.S. children and adolescents between the ages of 2 and 19 years old were overweight, and more than half of those children were considered obese. Recent data suggest that obesity rates are stabilizing, but prevalence remains high, and obesity as a public health issue has gained the attention of health care professionals, policymakers, schools, employers, and the media. Obesity increases mortality risk and is associated with a number of chronic conditions in children, such as diabetes, asthma, and risk factors for heart disease. Obese children are at a greater risk for obesity and other chronic conditions in adulthood. Some researchers believe that today's children may lead shorter lives than their parents due to the negative effects of obesity. In addition to those risks, obesity rates in children and adolescents have raised concerns about increased burden on the health care system and the effects of obesity on military readiness. Overweight and obesity often begin in childhood and adolescence and continue into adulthood. Adults are generally considered capable of understanding how to maintain a healthy weight, and are considered capable of making personal choices, when possible, to control their weight. However, children may not have the tools or capacity to understand or prevent overweight and obesity, and the government often has a larger influence on their well-being, through schools, health care, and programs for low-income families. The Obama Administration has shown a strong interest in developing policies to address childhood overweight and obesity. Childhood obesity is a major initiative of First Lady Michelle Obama, the Department of Health and Human Services (HHS), and the Department of Agriculture (USDA). The 2010 Dietary Guidelines for Americans (DGA), the White House Task Force on Childhood Obesity Report, and the Let's Move initiative have focused research and policy attention on improving the health of American children, especially in terms of weight status. The President's Task Force on Childhood Obesity released an action plan with a series of recommendations to reduce childhood obesity to 5% by 2030. Healthy People 2020 objectives aim for a 10% reduction, from 16.1% in 2005-2008 to 14.6% by 2020, and an increase in access to and consumption of nutritious foods. In some instances, activities are conducted subject to Congress's funding decisions in annual appropriations bills. In recent years, Congress has considered many approaches to these issues, including increased funding for school lunch programs, updating school meal nutrition standards, encouraging "farm-to-school" activities, and broadened coverage and support for school wellness programs. Many of these issues were addressed in the Healthy, Hunger-Free Kids Act ( P.L. 111-296 ), which is discussed in greater detail in CRS Report R41354, Child Nutrition and WIC Reauthorization: P.L. 111-296 . The Patient Protection and Affordable Care Act ( P.L. 111-148 ) appropriated $25 million for a Childhood Obesity Research Demonstration (CORD) project that was authorized in the 2009 CHIP reauthorization ( P.L. 111-3 ). Funded through September 2015, CORD provides funding for the development of a comprehensive and systematic model for reducing childhood obesity, through targeted support to families, the identification of behavioral risk factors, identification of needed clinical preventive, screening benefits, and medical assistance. Other approaches have addressed collection of program participant data on student fitness levels, nutrition behavior, and physical activity, in addition to higher physical education standards and required activity time in schools and child care settings. Additionally, Congress has expressed interest in coordination of these activities with private sector efforts. Some have suggested requirements for local education agencies to integrate fitness into the school environment and to disseminate information on physical activity to families. Others have called for nationwide physical education requirements in schools, which are currently determined at the local level. Programs such as Communities Putting Prevention to Work (CPPW) seek to address environmental determinants of obesity through initiatives that include increasing the availability of healthy food and beverages in schools, supporting development of sidewalks and bike lanes, and working with afterschool programs to implement physical activity requirements. Congress has at times required the collection of participant data, either to establish or compare to national benchmarks, to examine trends over time, or to evaluate programs. This report presents data on obesity among children and adolescents, and includes a discussion of obesity measurement, trends in obesity rates, and differences in rates that exist across gender, race, ethnicity, socioeconomic status, and geographic location. According to the Centers for Disease Control and Prevention (CDC), obesity and overweight are terms used to describe ranges of weight that are higher than what is generally considered healthy for a given height. While several methods are available to measure or estimate overweight and obesity, this report relies on the use of BMI to present the data on childhood overweight and obesity. While BMI is not an exact measure of body fat, as discussed below, it is regarded as an efficient measure of childhood overweight and obesity for population-based data. BMI is presented as the indicator of overweight and obesity in most federally sponsored studies and reports of children's health, including the National Health and Nutrition Examination Survey (NHANES) and Healthy People 202 0 . BMI is also the most commonly used clinical screening measure for both child and adult overweight and obesity, and is recommended by the U.S. Preventive Services Task Force (USPSTF) for screening purposes. One aspect of the discussion surrounding childhood overweight and obesity is the issue of measurement. Body mass index (BMI), a number calculated from a person's weight and height, is commonly used to screen for obesity. BMI is considered a reliable, easy, and inexpensive way to screen individuals over age two for possible weight problems. In addition to its use in research and surveillance, BMI is widely used in clinical settings. BMI is not a direct measure of body fat, but research has shown that BMI correlates with direct measures of body fat. BMI is used as a rapid and inexpensive screening tool; however, not all children with a high BMI are overweight or obese. Some children may be heavier due to extra muscle mass, not extra body fat. The CDC recommends that a child with a high BMI be examined by a health care provider to determine if overweight or obesity is a concern. BMI percentiles are determined using population-based growth charts developed by CDC that show age- and sex-specific BMI. These charts were created using reference populations from several surveys administered by CDC between 1963 and 1994. Consequently, when using BMI as an indicator of overweight and obesity today, the measure is referring to the BMI index levels of individuals based on their age, sex, weight, and height compared to their respective reference populations' BMI distributions from which the index was developed. In children, obesity is defined as being at or above the 95 th percentile of the age- and sex-specific BMI relative to those reference populations ; overweight, also known as "at risk for obesity," is defined as being between the 85 th and 94 th percentiles. In most children and adolescents, a BMI level at or above the 95 th percentile indicates elevated body fat and reflects the presence or risk of related chronic disease. The most recent NHANES data, including those corresponding to a higher cut point (>97 th percentile), are presented in Appendix B . Generally, children in the higher BMI percentile groups are at greater risk for metabolic complications (e.g., type 2 diabetes) and are more likely to become obese as adults. Because the CDC growth chart data is based on a "preobesity epidemic population," there is insufficient data to construct percentiles beyond the 97 th percentile, and CDC BMI growth charts cannot be used to characterize severely obese children and adolescents. Child health data are available from several sources, but the types of data and resulting analyses vary. This report presents data from several sources, including the National Health and Nutrition Examination Survey (NHANES), the Youth Risk Behavior Surveillance System (YRBSS), and the National Survey of Children's Health (NSCH). The Pediatric Nutrition Surveillance System (PedNSS) has been used to monitor the nutritional status of low-income children in federally funded programs from birth through age five, but was discontinued in 2012. All data used in this report are collected by HHS with the intent to monitor the nation's health. Each data source is described below, followed by a general discussion of the strengths and weaknesses of the data collected by each system. For a more detailed comparison of the data sources, see Appendix A . The National Health and Nutrition Examination Survey is a continuous national survey that uses mobile examination centers to conduct in-person interviews, physical examinations, diagnostic tests, and nutritional assessments on a nationally representative sample of about 5,000 people of all ages annually. BMI is calculated from direct measure of height and weight by survey staff. These data are available from 1976 to the present. Because the sample size is relatively small, state-level data for children and adolescents are not available from NHANES. The Youth Risk Behavior Surveillance System is composed of national, state, and local school-based surveys of students in grades 9 through 12. It is designed to monitor six categories of health-risk behaviors, including physical activity and dietary habits, in this age group. Participation is voluntary, and students are asked to complete the questionnaire during one class period. In 2013, approximately 13,500 students participated in YRBSS. Since 1991, the survey has been administered once every two years, and it is designed to be nationally representative of all U.S. students in grades 9 through 12. BMI is calculated based on the responses to questions about age, gender, height, and weight. The sample size is large enough to present state-level data, and data are often available from states, as well as from CDC.