Prevalence of Underweight Among Adults Aged 20 and Over: United States, 1960–1962 Through 2011–2012

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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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Poor nutrition or underlying health conditions in adults can result in underweight. Results from the 2011–2012 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 1.7% of U.S. adults aged 20 and over are underweight. Body mass index (BMI), expressed as weight in kilograms divided by height in meters squared (kg/m2), is commonly used to classify underweight (BMI less than 18.5) among adults aged 20 and over.

The age-specific and age-adjusted prevalence of underweight among adults aged 20 and over is shown in Table 1. Because surveys before 1988 did not include persons over age 74, Table 2 shows age-specific and age-adjusted prevalence estimates of underweight for adults aged 20–74 for all survey periods dating back to 1960.

NHANES, conducted by CDC’s National Center for Health Statistics (NCHS), is a multistage probability sample of the civilian noninstitutionalized population of the United States. A household interview and a physical examination are conducted for each survey participant. During the physical examination, conducted in a mobile examination center, height and weight are measured as part of a more comprehensive set of body measurements. These measurements are 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.

For additional information on NHANES methods, visit the NHANES methods page.

Tables

Table 1a. Prevalence of underweight among adults aged 20 and over, by age: United States, selected years 1988–1994 through 2011–2012
Survey period Sample (n) Total1 20–39 years 40–59 years 60 years and over
Percent (standard error)
1988–1994 16,235 2.3 (0.2) 3.0 (0.4) 1.7 (0.3) 2.3 (0.3)
1999–2000 4,117 2.0 (0.2) 2.9 (0.5) 1.3 (0.2) 1.4 (0.4)
2001–2002 4,413 1.9 (0.2) 2.9 (0.5) 0.9 (0.2) 3.0 (0.4)
2003–2004 4,431 1.7 (0.2) 2.8 (0.3) *1.0 (0.4) 0.8 (0.2)
2005–2006 4,356 1.9 (0.3) 2.4 (0.6) 1.4 (0.4) 1.6 (0.3)
2007–2008 5,550 1.6 (0.3) 1.9 (0.5) *1.5 (0.5) 1.1 (0.2)
2009–2010 5,926 1.8 (0.3) 2.0 (0.3) 2.1 (0.5) 1.3 (0.2)
2011–2012 5,181 1.7 (0.2) 2.5 (0.4) 0.9 (0.2) 1.6 (0.4)

* Estimate has a relative standard error greater than 30% and should be used with caution because it does not meet standards of reliability or precision.

1Age-adjusted by the direct method to the year 2000 U.S. Census Bureau estimates using the age groups 20–39, 40–59, and 60 and over.

NOTE: Underweight is body mass index less than 18.5 kg/m2. Pregnant females were excluded from analysis.

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey.

Table 1b. Age-adjusted prevalence of underweight among adults aged 20 and over, by sex: United States, selected years 1988–1994 through 2011–2012
Survey period Sample (n) Total Men Women
Percent (standard error)
1988–1994 16,235 2.3 (0.2) 1.1 (0.2) 3.5 (0.3)
1999–2000 4,117 2.0 (0.2) 1.1 (0.2) 2.7 (0.5)
2001–2002 4,413 1.9 (0.2) 1.0 (0.3) 2.7 (0.3)
2003–2004 4,431 1.7 (0.2) 1.4 (0.3) 2.0 (0.4)
2005–2006 4,356 1.9 (0.3) 1.2 (0.4) 2.5 (0.4)
2007–2008 5,550 1.6 (0.3) 1.0 (0.3) 2.2 (0.4)
2009–2010 5,926 1.8 (0.3) 1.0 (0.2) 2.6 (0.5)
2011–2012 5,181 1.7 (0.2) 0.7 (0.1) 2.6 (0.4)

NOTES: Underweight is body mass index less than 18.5 kg/m2. 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 and over. Pregnant females were excluded from analysis.

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey.

Table 2a. Prevalence of underweight among adults aged 20–74, by age: United States, selected years 1960–1962 through 2011–2012
Survey period Sample (n) Total1 20–39 years 40–59 years 60–74 years
Percent (standard error)
1960–1962 6,126 4.0 (0.3) 5.7 (0.4) 2.3 (0.3) 3.7 (0.6)
1971–1974 12,911 3.6 (0.2) 4.9 (0.4) 2.2 (0.3) 3.8 (0.4)
1976–1980 11,765 3.0 (0.2) 4.2 (0.3) 1.9 (0.3) 2.7 (0.4)
1988–1994 14,319 2.3 (0.2) 3.0 (0.4) 1.7 (0.3) 1.9 (0.3)
1999–2000 3,603 2.0 (0.2) 2.9 (0.5) 1.3 (0.2) 1.1 (0.2)
2001–2002 3,916 1.8 (0.2) 2.9 (0.5) 0.9 (0.2) 1.4 (0.4)
2003–2004 3,756 1.7 (0.2) 2.8 (0.3) *1.0 (0.4) *0.7 (0.3)
2005–2006 3,835 1.8 (0.3) 2.4 (0.6) 1.4 (0.4) *1.1 (0.5)
2007–2008 4,876 1.6 (0.3) 1.9 (0.5) *1.5 (0.5) 0.9 (0.2)
2009–2010 5,279 1.9 (0.3) 2.0 (0.3) 2.1 (0.5) 1.2 (0.3)
2011–2012 4,674 1.7 (0.2) 2.5 (0.4) 0.9 (0.2) *1.2 (0.5)

* Estimate has a relative standard error greater than 30% and should be used with caution because it does not meet standards of reliability or precision.

1Age-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.

NOTE: Underweight is body mass index less than 18.5 kg/m2. Pregnant females were excluded from analysis.

SOURCE: CDC/NCHS, National Health Examination Survey (NHES) 1960–1962 and National Health and Nutrition Examination Surveys (NHANES) 1971–1974 , 1976–1980, 1988–1994, and 1999–2012. Because NHES 1960–1962 and NHANES 1971–1974 and 1976–1980 did not include individuals over age 74, trend estimates are based on ages 20–74.

Table 2b. Age-adjusted prevalence of underweight among adults aged 20–74, by sex: United States, selected years 1960–1962 through 2011–2012
Survey period Sample (n) Total Men Women
Percent (standard error)
1960–1962 6,126 4.0 (0.3) 2.2 (0.3) 5.7 (0.4)
1971–1974 12,911 3.6 (0.2) 2.4 (0.3) 4.8 (0.3)
1976–1980 11,765 3.0 (0.2) 1.6 (0.2) 4.4 (0.3)
1988–1994 14,319 2.3 (0.2) 1.1 (0.2) 3.5 (0.3)
1999–2000 3,603 2.0 (0.2) 1.2 (0.2) 2.7 (0.6)
2001–2002 3,916 1.8 (0.2) 1.0 (0.3) 2.6 (0.4)
2003–2004 3,756 1.7 (0.2) 1.4 (0.3) 2.1 (0.4)
2005–2006 3,835 1.8 (0.3) 1.3 (0.4) 2.4 (0.5)
2007–2008 4,876 1.6 (0.3) *0.9 (0.3) 2.3 (0.4)
2009–2010 5,279 1.9 (0.3) 1.0 (0.3) 2.7 (0.6)
2011–2012 4,674 1.7 (0.2) 0.7 (0.1) 2.6 (0.4)

* Estimate has a relative standard error greater than 30% and should be used with caution because it does not meet standards of reliability or precision.

NOTES: Underweight is body mass index less than 18.5 kg/m2. 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. Pregnant females were excluded from analysis.

SOURCE: CDC/NCHS, National Health Examination Survey (NHES) 1960–1962 and National Health and Nutrition Examination Surveys (NHANES) 1971–1974 , 1976–1980, 1988–1994, and 1999–2012. Because NHES 1960–1962 and NHANES 1971–1974 and 1976–1980 did not include individuals over age 74, trend estimates are based on ages 20–74.

This Health E-Stat supersedes the earlier version below: