Prevalence of Underweight Among Children and Adolescents: United States, 2003-2006

by Cheryl D. Fryar, M.S.P.H., and Cynthia L. Ogden, Ph.D., Division of Health and Nutrition Examination Surveys

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Underlying health conditions can result in underweight. In addition, among children underweight can reflect acute malnutrition. Results from the 2003-2006 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 3.3% of children and adolescents aged 2-19 years are underweight (see table). Trends from 1971-1974 to 2003-2006 show that there has been an overall significant decrease in underweight among children and adolescents from 5.1% to 3.3%. Underweight significantly decreased from 5.8% to 2.8% among 2-5 year olds and from 5.3% to 2.7% among 6-11 year olds between 1971-1974 and 2003-2006. Among adolescents aged 12-19, underweight decreased although not significantly from 4.7% to 3.8% during the same time period. Surveys before 1971 did not include children 2-5 years.

Body mass index (BMI), expressed as weight/height² (BMI;kg/m²) is commonly used to classify weight status among adults, and is also recommended to identify children’s weight status. Cutoff criteria are based on the sex specific 2000 CDC BMI-for-age growth charts for the United States. Based on current recommendations of expert committees, children with BMI values below the 5th percentile of the sex specific BMI-for-age growth charts are categorized as underweight.

NHANES used a stratified multistage probability sample of the U.S. civilian noninstitutionalized population. A household interview and a physical examination were conducted for each survey participant. During the physical examination (conducted in mobile examination centers), height and weight were measured as part of a more comprehensive set of body measurements. These measurements were taken by trained health technicians using standardized measuring procedures and equipment. Observations for persons missing a valid height or weight measurement were not included in the data analysis.

Table. Prevalence of underweight among children and adolescents aged 2-19 years: United States, selected years 1963-1965 through 2003-2006

Age (in years)1	NHANES (1963-1965 and 1966-1970)2	NHANES (1971-1974)	NHANES (1976-1980)	NHANES (1988-1994)	NHANES (1999-2002)	NHANES (2003-2006)
Total	-	5.1	4.5	4.0	3.7	3.3
2-5	-	5.8	5.3	4.3	3.8	2.8
6-11	5.8	5.3	4.2	3.9	3.8	2.7
12-19	4.6	4.7	4.4	3.9	3.7	3.8

- Quantity zero.

¹ Excludes pregnant girls starting with 1971-1974. Pregnancy status not available for 1963-1965 and 1966-1970.

² Data for 1963-1965 are for children 6-11 years of age; data for 1966-1970 are for adolescents 12-17 years of age, not 12-19 years.

NOTE: NHANES is National Health and Nutrition Examination Survey.