Since the 1970s there has been a steady and dramatic increase in overweight and obesity in the entire U.S. population. In 1991, the Centers for Disease Control and Prevention (CDC) had documented through the Behavioral Risk Factor Surveillance System (BRFSS) that four states had adult obesity prevalence rates of 15 to 19 percent and that no states had rates at or above 20 percent. By 2004, seven states had adult obesity prevalence rates of 15 to 19 percent, 33 states had adult obesity rates of 20 to 24 percent, and nine states had adult obesity rates of 25 percent or greater (CDC, 2005a).
Obesity rates among American children and youth have also increased significantly. Between 1963 and 2004, obesity rates quadrupled for older children, ages 6 to 11 years (from 4 to 19 percent), and tripled for adolescents, ages 12 to 19 years (from 5 to 17 percent) (Figure 1-2) (CDC, 2005b; Ogden et al., 2002, 2006). Between 1971 and 2004, obesity rates increased from 5 to 14 percent in 2- to 5-year-olds (Figure 1-2) (Ogden et al., 2006).3 Given these trends, it does not appear that the Healthy People 2010 target of reducing childhood obesity to 5 percent of the population (DHHS, 2000, 2004) will be reached by 2010.
At present, one-third (33.6 percent) of American children and adolescents are either obese or at risk of becoming obese (Ogden et al., 2006). National Health and Nutrition Examination Survey (NHANES) data show that the national obesity prevalence for 2- to 19-year olds was 13.9 percent in 1999–2000, which increased to 15.4 percent in 2001–2002 and to 17.1 percent in 2003–2004. In 2003–2004, 16.5 percent of 2- to 10-year olds were at risk of becoming obese (Ogden et al., 2006).
Between 1999–2000 and 2003–2004, the prevalence of obesity among girls increased from 13.8 to 16.0 percent and among boys increased from 14.0 to 18.2 percent (Ogden et al., 2006). Obesity prevalence rates in children and youth reveal significant differences by sex and between racial/ethnic and socioeconomic groups (Chapter 3) (Ogden et al., 2006). By 2010, it is projected that an estimated 20 percent of children and youth in the United States will be obese if the current trajectory continues (Sondik, 2004).
Although surveillance systems have tracked children’s and adolescents’ weight trends since the 1960s for those ages 6 years and older, a rise in obesity prevalence was not observed until the late 1970s. Obesity prevalence estimates are often averaged across a span of years. The prevalence was estimated at 16 percent for 1999–2002 (CDC, 2005b).