Journal Issue: Childhood Obesity Volume 16 Number 1 Spring 2006
Obesity Prevalence among Minority and Low-Income Children
No single data source provides information on trends in child obesity for all the major racial and ethnic groups in the United States. The National Health and Nutrition Examination Survey (NHANES), a nationally representative survey that has been conducted periodically since the early 1970s, has large enough samples of white, African American, and (since 1982) Mexican American children to estimate obesity rates within racial and ethnic groups at different points in time. Table 1, which is based on NHANES data, shows rates of obesity for white, African American, and Mexican American boys and girls in two age groups, ages six to eleven and twelve to nineteen, for three time periods since the mid-1970s. Although obesity rates have increased for boys and girls within each ethnic and racial group, they have increased more for African American and Mexican American children. By 1999–2002, obesity rates were higher for both of these two groups than for white children within each age and gender group. In some cases, obesity rates for ethnic minority children exceeded rates for white children by 10 to 12 percentage points. For boys of both age groups, the obesity rate among Mexican Americans exceeded that among African Americans. For example, nearly a quarter of Mexican American adolescent boys were obese in 1999–2002, as against 19 percent of African Americans and 15 percent of whites. This pattern differs for girls, with the highest obesity rates found among African American girls. For example, among adolescent girls, 24 percent of African Americans, 20 percent of Mexican Americans, and 13 percent of whites were obese.
Several other ethnic minority groups have high rates of child obesity. Measures of obesity for preschool children participating in Hawaii's Supplemental Nutrition Program for Women, Infants, and Children (WIC) indicate that more than a quarter of Samoan children are obese, a rate more than double that for any other ethnic subgroup represented in the sample.3 Note, however, that the WIC sample is not representative—families must be low-income and nutritionally “at risk” to qualify. Obesity rates are also high among American Indian children. A large Indian Health Service study estimated obesity prevalence at 22 percent for boys and 18 percent for girls based on data for more than 12,000 five- to seventeen- year-old American Indian children in North and South Dakota, Iowa, and Nebraska.4 A study of seven American Indian communities in Arizona, New Mexico, and South Dakota reported obesity prevalence of 26.8 percent for boys and 30.5 percent for girls based on data for 1,704 elementary school children with an average age of 7.6 years.5 As with U.S. children generally, trend data for Navajo six- to twelve-year-olds showed an increase in obesity rates over time.6
Asian American children are an exception to the general pattern of higher obesity rates among ethnic minority groups. A 2003 study of New York City elementary school children found obesity rates of 31 percent for Hispanics, 23 percent for African Americans, 16 percent for whites, and 14 percent for Asian Americans.7 Another study compared overweight (with an 85th percentile BMI cutoff) for white, African American, Hispanic, and Asian American adolescents in 1996, using data from the National Longitudinal Study of Adolescent Health.8 This survey of more than 14,000 students in seventh through twelfth grade indicates that Asian American adolescents have relatively low rates of overweight. The share of boys that were overweight was 23 percent among Asian Americans, 26 percent among African Americans, 27 percent among whites, and 28 percent among Hispanics. Among girls, only 10 percent of Asian Americans were overweight, as against 22 percent of whites, 30 percent of Hispanics, and 38 percent of African Americans. However, in adults, a BMI below the usual cutoff for obesity is associated with higher health risks in people of Asian origin when compared to other populations.9 If this case is also true in children, the lower prevalence of obesity in Asian American children does not necessarily reflect an equivalent lower level of health risk.
Low-income children are at excess risk of obesity regardless of ethnicity, although ethnic differences in pediatric obesity appear at lower-income levels.10 Several authors have analyzed NHANES data on the links between socioeconomic status and obesity among children and youth overall and in specific age groups.11 One analysis of two- to nineteen-year-old children in NHANES surveys between 1971–74 and 1999–2002 finds higher rates of obesity among low-income children than among all children after 1976–80.12 Similarly, the National Longitudinal Survey of Youth for four- to twelve-year-olds indicates that low-income children have higher obesity rates than do wealthier children.13
The association between socioeconomic status and obesity in school-aged children and adolescents varies by ethnicity and gender and appears to be quite complex.14 In general, among white children, obesity typically declines as income and parental education increase. Different patterns have been found for children from ethnic minority groups. For example, among twelve- to seventeen-year-old non-Hispanic white children in the 1988–94 NHANES survey, rates of obesity decline for both boys and girls as family income increases. By contrast, among African Americans and Mexican Americans, girls' obesity rates increase with income; boys' rates show no consistent pattern.15 Another study found that although rates of obesity for white girls decrease as family income rises, rates for African American girls are higher in the lowest and highest income ranges than in the in-between bracket.16 For both groups, however, obesity rates decline with higher parental education. An analysis of the National Heart, Lung, and Blood Institute Growth and Health Study also noted ethnic differences in the relationship between socioeconomic status and obesity.17 It found the expected inverse link between obesity and both parental income and education— with obesity decreasing as income or education increased—in white girls but not in African American girls. Overall, these studies indicate that differences in obesity rates across race and ethnic groups do not simply reflect differences in the average socioeconomic status across groups.
In summary, obesity rates are higher for African American and Hispanic children and adolescents than for their white peers. Among African Americans rates are particularly high among girls, although the disparity varies by age and socioeconomic status. Hispanic boys seem to be at particularly high risk for obesity. Obesity rates for American Indian children appear to be comparable to or in some cases higher than those for African American children. Samoan children are also at high risk. Asian American children, by contrast, are less likely than those from other ethnic groups to be obese by standard definitions although the applicability of the standard definitions to Asian Americans is unclear. Although poorer children are more likely to be obese when all children are considered, this link varies across ethnic and racial groups.