Child Overweight and Obesity

Narrative

Childhood overweight and obesity is a significant public health issue, affecting nearly a third of all children in the United States.1 Obese children are at increased risk of several adverse health outcomes, including high blood pressure and cholesterol, asthma, and many other chronic physiologic and psychosocial health conditions.2 Childhood obesity is also associated with obesity in adulthood and children who are overweight are more likely to have severe obesity in adulthood.5

Body mass index (BMI) is the ratio of weight to height squared that is used to define overweight and obesity. In children, BMI is categorized as a function of age and sex, since both of these factors affect body composition. Children below the 5th percentile of BMI for age are considered underweight, those between the 5th and 84th percentiles are considered to have a normal weight, those between the 85th and 94th percentiles are considered overweight, and those in the 95th percentile or above are considered obese. In 2011–2012, nearly 30 percent of children aged 2–11 years were overweight or obese, 66.9 percent were of normal weight, and 3.4 percent were underweight based on measured height and weight.

Children’s weight status varies by a number of factors, including age, sex, and race and ethnicity. For example, school-aged children are more likely to be obese than preschool-aged children. In 2011–2012, 17.7 percent of children aged 6–11 years were obese, compared to 8.4 percent of children aged 2–5 years (Figure 1). The percent of children who were overweight was similar by age: 14.5 percent of 2- to 5-year-olds and 16.5 percent of 6- to 11-year-olds.

weight status by sex and age

Figure 1 Source

With regard to race and ethnicity, nearly 40 percent of Hispanic children and 31.4 percent of non-Hispanic Black children aged 6–11 years were overweight or obese overall. By comparison, 26.1 percent of non-Hispanic White children and 15.5 percent of non-Hispanic Asian children were overweight or obese. Racial and ethnic differences in obesity were particularly pronounced among males: 18.6 percent of non-Hispanic Black males and 24.2 percent of Hispanic males were obese, compared to 7.9 percent of their non-Hispanic White counterparts (Figure 2).

weight status by sex and race

Figure 2 Source

Several strategies may prevent childhood obesity, such as increasing physical activity, eating right, and reducing screen time. Dietary strategies for preventing childhood obesity include limiting access calories from fats and sugars, consuming smaller portions, and increasing intake of whole grains, vegetables, and fruits.6 The 2008 Physical Activity Guidelines for Americans recommend that children aged 6–11 years participate in 60 minutes or more per day of aerobic activity.3 The recommended amount of fruits and vegetables is 1–1.5 cups of each for children aged 2–8 years.4 Recommendations for children aged 9 years and older vary depending on their age, sex, and activity level. The Community Preventive Services Task Force also recommends behavioral interventions for reducing screen time (e.g., time spent watching television, playing computer games, or browsing the Internet) to improve physical activity, diet, and weight-related outcomes.7

Data Sources

Figure 1. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Health and Nutrition Examination Survey, 2011–2012. Unpublished estimates. Analyses conducted by the National Center for Health Statistics.

Figure 2. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Health and Nutrition Examination Survey, 2011–2012. Unpublished estimates. Analyses conducted by the National Center for Health Statistics.

Endnotes

1 Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of childhood and adult obesity in the United States, 2011–2012. Journal of the American Medical Association. 2014;311(8):806–814.

2 U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Childhood Overweight and Obesity. 2012. Accessed September 5, 2014.

3 U.S. Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans. 2008. Accessed September 5, 2014.

4 U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Strategies To Prevent Obesity and Other Chronic Diseases: The CDC Guide to Strategies To Increase the Consumption of Fruits and Vegetables. Atlanta: U.S. Department of Health and Human Services; 2011.

5 Centers for Disease Control and Prevention. 2012. Basics about childhood obesity. Accessed February 17, 2015.

6 U.S. Department of Agriculture and U.S. Department of Health and Human Services. 2010. Dietary Guidelines for Americans 2010. Accessed February 12, 2015.

7 Guide to Community Preventive Services. Obesity prevention and control: behavioral interventions that aim to reduce recreational sedentary screen time among children. Accessed September 5, 2014.

Data

Statistical Significance Test

Calculate the difference between two estimates:

Calculated Z-Test Result 0.9567433 Not statistically significant

We follow statistical conventions in defining a significant difference by a p-value less than 0.05 where there is a less than 5% probability of observing a difference of that magnitude or greater by chance alone if there were really no difference between estimates. The 95% confidence interval includes a plausible range of values for the observed difference; 95% of random samples would include the true difference with fewer than 5% of random samples failing to capture the true difference.

This website allows comparisons between two estimates using the independent z-test for differences in rates or proportions. This test is appropriate for comparing independent populations across years (e.g., 2011 versus 2012) or subgroups (e.g., Male versus Female) on corresponding measures. To the extent possible, the functionality of this application has limited estimate comparisons based on appropriate use of the independent z-test. However, some tables present subgroup categories within broader categories that will allow comparisons between non-independent populations (e.g., low birth weight and very low birth weight). Users should exercise caution when interpreting these test results, which will frequently overstate statistical significance.

For some tables, the website does not allow for comparisons between two estimates, even though the data represent independent populations. Generally, this is because the standard errors were not publicly available at the time this website was created.

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