Prevalence of Obesity Among Youths by Household Income and Education Level of Head of Household — United States 2011–2014

Obesity prevalence varies by income and education level, although patterns might differ among adults and youths (1–3). Previous analyses of national data showed that the prevalence of childhood obesity by income and education of household head varied across race/Hispanic origin groups (4). CDC analyzed 2011–2014 data from the National Health and Nutrition Examination Survey (NHANES) to obtain estimates of childhood obesity prevalence by household income (≤130%, >130% to ≤350%, and >350% of the federal poverty level [FPL]) and head of household education level (high school graduate or less, some college, and college graduate). During 2011–2014 the prevalence of obesity among U.S. youths (persons aged 2–19 years) was 17.0%, and was lower in the highest income group (10.9%) than in the other groups (19.9% and 18.9%) and also lower in the highest education group (9.6%) than in the other groups (18.3% and 21.6%). Continued progress is needed to reduce disparities, a goal of Healthy People 2020. The overall Healthy People 2020 target for childhood obesity prevalence is <14.5% (5).

NHANES is a cross-sectional survey designed to monitor the health and nutritional status of the civilian noninstitutionalized U.S. population (6). The survey consists of in-home interviews and standardized physical examinations conducted in mobile examination centers. The NHANES sample is selected using a complex, multistage probability design. During 2011–2014, non-Hispanic black, non-Hispanic Asian, and Hispanic persons, among other groups, were oversampled. Any non-Hispanic person reporting more than one race was included in an “other” category and included in the total estimates but not reported separately. The NHANES response rate for youths aged <20 years was 77.6% during 2011–2012 and 76.1% during 2013–2014. During the physical examination, standardized measurements of weight and height were obtained. Body mass index (BMI) was calculated as weight in kilograms divided by height in meters squared, rounded to the nearest 10th. Obesity among youths was defined as a BMI at or above the age- and sex-specific 95th percentile of the 2000 CDC growth charts (https://www.cdc.gov/growthcharts/cdc_charts.htm).

Household income was defined using FPL information, which accounts for inflation and family size (https://aspe.hhs.gov/prior-hhs-poverty-guidelines-and-federal-register-references) and categorized as ≤130%, >130% to ≤350%, and >350% of FPL. The cut-off point for participation in the Supplemental Nutrition Assistance Program is 130% of FPL, and 350% provides relatively equal sample sizes for each income group. Education was defined using education level of head of household and was categorized as a high school graduate or less, some college, and college graduate.

All estimates accounted for the complex survey design including examination sample weights. Confidence intervals for estimates were constructed using the Korn and Graubard method (7). Differences between groups were tested using a 2-sided univariate t statistic (p<0.05). Linear and quadratic trends from 1999–2002 to 2011–2014 were conducted using 4-year survey cycles. Pregnant females and persons with missing weight or height were excluded (139) for a total sample size of 6,878 during 2011–2014. For estimates by FPL another 517 persons were missing data and were excluded from analyses of FPL; for estimates by education level, 224 persons were missing data and were excluded from analyses of education.

Overall, 17.0% of youths aged 2–19 years had obesity during 2011–2014 (Table). The prevalence was 18.9% among those in the lowest income group, 19.9% among those in the middle group, and 10.9% among those in the highest income group. Among females, patterns in non-Hispanic white, non-Hispanic Asian, and Hispanic youths were similar, with the prevalence of obesity lower in the highest income group than in both other groups, but the differences by income were statistically significant only among non-Hispanic white females. Obesity prevalence did not differ by income among non-Hispanic black females. Among males, there was a lower obesity prevalence in the highest income group only in non-Hispanic Asian youths (compared with the lowest income group) and Hispanic youths (compared with both other income groups).

Among youths, the prevalence of obesity decreased with increasing level of education of the head of household: 21.6% (high school graduate or less), 18.3% (some college), and 9.6% (college graduate). The same pattern was seen overall and in females and males in all race-Hispanic origin groups, but differences were not significant for non-Hispanic black youths (total, male, or female) or non-Hispanic Asian males or females.

From 1999–2002 to 2011–2014 the prevalence of obesity increased among females in the two lowest income groups (Figure 1). There was a nonsignificant decrease in obesity prevalence among females in the highest income group, and the difference in childhood obesity prevalence between the lowest and highest income groups increased over time. Among males, a quadratic trend was observed in the lowest income group: obesity prevalence was 16.9% during 1999–2002, increased to 21.0% during 2007–2010, and then declined to 18.1% during 2011–2014. The difference in prevalence between the lowest and highest income groups did not change over time for males.

Obesity prevalence among youths increased from 1999–2002 to 2011–2014 among females and males in households headed by persons with the least education (high school graduate or less) and among females in households headed by persons with some college education. There were no other significant trends. In addition, the difference in childhood obesity prevalence between the lowest and highest head of household education groups increased over time for females but not for males (Figure 2).

Corresponding author: Cynthia L. Ogden, [email protected], 301-458-4405.

¹Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, CDC; ²Office of Analysis and Epidemiology, National Center for Health Statistics, CDC; ³Division of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion, CDC.

References

1. Wang Y, Zhang Q. Are American children and adolescents of low socioeconomic status at increased risk of obesity? Changes in the association between overweight and family income between 1971 and 2002. Am J Clin Nutr 2006;84:707–16. PubMed
2. Singh GK, Kogan MD, Van Dyck PC, Siahpush M. Racial/ethnic, socioeconomic, and behavioral determinants of childhood and adolescent obesity in the United States: analyzing independent and joint associations. Ann Epidemiol 2008;18:682–95. CrossRef PubMed
3. Ogden CL, Fakhouri TH, Carroll MD, et al. Prevalence of obesity among adults, by household income and education—United States, 2011–2014. MMWR Morb Mortal Wkly Rep 2017;66:1369–73. CrossRef PubMed
4. Ogden CL, Lamb MM, Carroll MD, Flegal KM. Obesity and socioeconomic status in children and adolescents: United States, 2005–2008. NCHS Data Brief 2010;51:1–8. PubMed
5. National Center for Health Statistics. Healthy People 2020 midcourse review. Chapter 29: nutrition and weight status. Hyattsville, MD: US Department of Health and Human Services, CDC, National Center for Health Statistics; 2016. https://www.cdc.gov/nchs/data/hpdata2020/HP2020MCR-C29-NWS.pdf
6. National Center for Health Statistics. National Health and Nutrition Examination Survey. Hyattsville, MD: US Department of Health and Human Services, CDC, National Center for Health Statistics; 2011. https://www.cdc.gov/nchs/nhanes/index.htm
7. Korn EL, Graubard BI. Confidence intervals for proportions with small expected number of positive counts estimated from survey data. Surv Methodol 1998;24:193–201.
8. Lamerz A, Kuepper-Nybelen J, Wehle C, et al. Social class, parental education, and obesity prevalence in a study of six-year-old children in Germany. Int J Obes 2005;29:373–80. CrossRef PubMed
9. Asian Pacific Islander Health Forum. Obesity and overweight among Asian American children and adolescents. Oakland, CA: Asian Pacific Islander Health Forum; 2016. http://www.apiahf.org/resources/resources-database/obesity-and-overweight-among-asian-american-children-and-adolescents
10. Freedman DS, Ogden CL, Flegal KM, Khan LK, Serdula MK, Dietz WH. Childhood overweight and family income. MedGenMed 2007;9:26. PubMed

Abbreviation: CI = confidence interval.
* Significantly different from ≤130% of FPL, p<0.05.
^† Significantly different from >130% to ≤350% of FPL, p<0.05.
^§ Estimate might be unreliable because relative standard error is between 30% and 40%.
^¶ Estimate might be unreliable because relative standard error is >40%.
** Significantly different from high school graduate or less, p<0.05.
^†† Significantly different from some college, p<0.05.

FIGURE 1. Trends*^,† in obesity prevalence among youths (persons aged 2–19 years), by household income — National Health and Nutrition Examination Survey, United States, 1999–2002 through 2011–2014

Abbreviation: FPL = federal poverty level.

* Linear trend (p<0.05) for females ≤130% of FPL, >130% to ≤350% of FPL.

^† Quadratic trend (p<0.05) for males ≤130% of FPL.

The figure above is a line graph showing trends in obesity prevalence among youths (persons aged 2–19 years), by household income, in the United States, from 1999–2002 through 2011–2014.

FIGURE 2. Trends* in prevalence of obesity among youths (persons aged 2–19 years), by education level of head of household — National Health and Nutrition Examination Survey, United States, 1999–2002 through 2011–2014

* Linear trend (p<0.05) for females, high school graduate or less and some college, and males, high school graduate or less.

The figure above is a line graph showing trends in prevalence of obesity among youths (persons aged 2–19 years), by education level of head of household, in the United States, from 1999–2002 through 2011–2014.