Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home

About NCHS

NCHS Fact Sheet

May 2014

National Health and Nutrition Examination Survey

PDF Version (223 KB)

About NCHS

The CDC’s National Center for Health Statistics (NCHS) is the nation’s principal health statistics agency, providing data to identify and address health issues. NCHS compiles statistical information to help guide public health and health policy decisions.

Collaborating with other public and private health partners, NCHS employs a variety of data collection mechanisms to obtain accurate information from multiple sources. This process provides a broad perspective to help us understand the population’s health, influences on health, and health outcomes.

National Health and Nutrition Examination Survey (NHANES)

The NHANES is NCHS’ most in-depth and logistically complex survey, designed to assess the health and nutritional status of adults and children in the United States. This comprehensive survey combines personal interviews with standardized physical examinations, diagnostic procedures, and lab tests.

Diseases, medical conditions, health indicators studied:

  • Obesity
  • Diabetes
  • Sexual behavior
  • Kidney disease
  • Oral health
  • Physical activity
  • Nutrition
  • Infectious diseases
  • Osteoporosis
  • Cardiovascular disease
  • Cognitive functioning
  • Environmental exposures
  • Reproductive history
  • Sexually transmitted diseases
  • Supplements and medications

Why is NHANES unique?

  • Annually, NHANES examines a nationally representative sample of 5,000 individuals of all ages. To produce reliable statistics, NHANES oversamples African Americans, Asian Americans, Hispanics, and persons over age 60.
  • Inclusion of an examination component allows the survey to provide an objective assessment of the prevalence of both diagnosed and undiagnosed medical conditions in the United States.
  • The physical exams are conducted in mobile examination centers that travel to 15 U.S. sites annually, allowing trained specialists to work in quality controlled settings.
  • Findings from this survey are used to determine the prevalence of major diseases and risk factors for diseases.
  • Participants receive a report of their medical findings and appropriate referrals if needed.
  • These data produce national references for such measurements as height and weight (pediatric growth charts), and blood pressure.
  • NHANES serves as the data collection mechanism for a joint Health and Human Services/U.S. Department of Agriculture effort to monitor the diet and nutritional status of Americans, providing information needed for food policy and dietary guidelines.
  • NHANES data can be linked to Medicare and National Death Index records to permit studies of disease outcomes.

Methods of data collection

  • Home-based interviews
  • Mobile examination centers
    • Physical exams
    • Standardized dental exams
    • Physiological measurements
    • Laboratory tests on blood and urine

Examples of NHANES Data

Obesity among adults

  • More than one-third of U.S. adults (34.9 percent) were obese in 2011-2012. This includes 33.5 percent of men and 36.1 percent of women. There was no significant change in the prevalence of obesity among all men or all women between 2003-2004 and 2011-2012.
  • The prevalence of obesity among middle aged adults aged 40-59 (39.5 percent) was higher than among younger adults aged 20-39 (30.3 percent) or older adults aged 60 and over (35.4 percent) in 2011-2012.
  • The prevalence of obesity in women aged 60 years and older increased between 2003-2004 and 2011-2012.

Figure 1 is a bar chart that shows the prevalence of obesity among adults 20 years and over by sex and race and Hispanic origin in the U.S. for 2011-2012
NOTE: Obesity defined as BMI ≥ 30 kg/m2.
Source: National Health and Nutrition Examination Survey, 2011-2012.


  • The overall prevalence of hypertension among U.S. adults was 29.1 percent in 2011-2012, and was similar among men (29.7 percent) and women (28.5 percent).
  • During 2011-2012, among adults with hypertension, 82.7 percent were aware of their hypertension, 75.6 percent reported currently taking prescribed medication to lower their blood pressure, and 51.8 percent had their blood pressure controlled.
  • There was no significant change in awareness, treatment, or control among adults with hypertension from 2009-2010 to 2011-2012.

Figure 2 is a bar chart that shows the awareness, treatment and control of hypertension among adults iwth hypertension in the U.S. from 2009-2012.
Source: National Health and Nutrition Examination Survey, 2011-2012.

Challenges and Future Opportunities

  • Due to the comprehensive nature of the interviews and examinations as well as increasing challenges in reaching participants in the household, it is increasingly difficult to maintain survey response rates. In addition, the oversampling of some special populations increases the likelihood that interviewers will encounter linguistic and cultural barriers to participation.
  • As health issues and biomedical science advance, a continuing need exists to develop new components in NHANES and related surveys to ensure that needed information can be collected using state-of-the art methods.

For further information about NCHS and its programs, visit us at

For further information on NHANES, visit us at

Contact Us:
  • National Center for Health Statistics
    3311 Toledo Rd
    Room 5419
    Hyattsville, MD 20782-2064
  • 1 (800) 232-4636
    TTY: 1 (888) 232-6348
  • Contact CDC–INFO
  • Page last reviewed: November 6, 2015
  • Page last updated: June 10, 2014
  • Content source: CDC/National Center for Health Statistics
  • The U.S. Government's Official Web PortalDepartment of Health and Human Services
    Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30329-4027, USA
    800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC-INFO