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NCHS Health E-Stat
Prevalence of Underweight Among Adults: 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
PDF Version (70 KB)
Poor nutrition or underlying health conditions can result in underweight. Results from the 2003-2006 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 1.8% of U.S. adults are underweight, as shown in Table 1. A statistically significant decrease in the prevalence of underweight between 1988-1994 and 2003-2006 was found only among persons who were aged 60 years and over. The prevalence in this age group was 2.3% in 1988-1994 and 1.2% in 2003-2006.
Surveys before 1988 did not include individuals over 74 years of age, and consequently, Table 2 contains age-adjusted prevalence estimates for adults aged 20-74 years for all survey periods back to 1960. The prevalence of persons who were underweight over the last 45 years has significantly decreased. Underweight prevalence went from an estimated 4% in the early 60s to approximately 2% in 2003-2006. This decrease in prevalence of underweight was found among all age groups.
Body mass index (BMI), expressed as weight/height2 (BMI; kg/m2) is commonly used to classify underweight (BMI less than 18.5) among adults (aged 20 years and over). 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 pregnant women and for persons missing a valid height or weight measurement were not included in the data analysis.
|Age (in years)||NHANES III (1988-1994)||NHANES (1999-2002)||NHANES (2003-2006)|
|60 or over||2.3||1.6||1.2|
1 Age adjusted by the direct method to the year 2000 U.S. Census Bureau estimates using the age groups 20-39, 40-59, and 60 years and over.
NOTE: NHANES is National Health and Nutrition Examination Survey.
|Age (in years)||NHES I (1960-1962)||NHANES I (1971-1974)||NHANES II (1976-1980)||NHANES III (1988-1994)||NHANES (1999-2002)||NHANES (2003-2006)|
1 Age adjusted by the direct method to the year 2000 U.S. Census Bureau estimates using the age groups 20-39, 40-59, and 60-74 years.
NOTE: The National Health Examination Survey (NHES) I and the National Health and Nutrition Examination Survey (NHANES) I and II did not include individuals over 74 years of age, thus trend estimates are based on age 20-74 years.