Nutrition Diet and Weight Issues Among Children and Adolescents - How Many Children And Teens Are Overweight?, Why Are So Many Children And Teens Overweight?, Health Risks And Consequences

One of the most disturbing observations about overweight and obesity in the United States is the epidemic of super-sized kids. A survey of adolescents in thirteen European countries, the United States, and Israel found that the United States, followed by Greece and Portugal, had the highest percentage of overweight teens (Inge Lissau et al., "Body Mass Index and Overweight in Adolescents in Thirteen European Countries, Israel, and the United States," Archives of Pediatrics and Adolescent Medicine, vol. 158, no. 1, January 2004). In 2006 more than twice as many American children and adolescents are seriously overweight than were overweight just twenty-five years ago. While there is no generally accepted definition for obesity as distinct from overweight in children and adolescents, the percentage of children who are overweight has quadrupled (from 4% to 16%) and the prevalence of overweight among adolescents has more than tripled (from 5% to 16%) since the 1960s. (See Figure 4.1.)

With children and teens as well as adults, body mass index (BMI; a formula describing the relationship between height and weight) is used to determine underweight, overweight, and at risk for overweight. Children's body fatness changes over the years as they grow, and girls and boys differ in their body fatness as they mature. In light of these differences, BMI for children (also referred to as BMI-for-age) is gender and age-specific. For example, Table 4.1 shows the BMI of a boy as he ages from two to thirteen years of age, with a typical decline in BMI during the preschool years and subsequent increases. Despite changing BMI with age, the boy in this example remains in the 95th percentile—at the cut-off point for overweight.

Overweight is defined as at or above the age- and gender-specific 95th percentile on the body mass index. Still, even children at the 85th percentile are considered at risk for overweight- and obesity-induced illness and overweight throughout their adult lives. Figure 4.2 shows BMI-for-age percentiles for boys aged two to twenty, and Figure 4.3 shows the comparable sex- and age-specific BMI percentiles for girls aged two to twenty.

Overweight children are much more likely to become overweight adults—an estimated 30% of adult obesity begins in childhood—unless they adopt and maintain healthier patterns of eating and exercise. The prevalence of overweight among adolescents is of particular concern because overweight adolescents are at even greater risk than overweight children of becoming overweight adults.

Like adults, children and adolescents are eating more than ever and exercising less. Although the link between obesity and disease in adolescence is weaker than it is for obese adults, teens who are overweight are at high risk of health problems later in life, and 50% to 80% of obese teens become obese adults. Type 2 diabetes, high blood lipid levels, and hypertension (high blood pressure) occur with increased frequency among overweight youth. Overweight children and teens are also at risk for psychosocial problems ranging from teasing and ostracism to social isolation and discrimination.

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