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What are overweight and
obesity?
How are weight-related
health risks determined?
Body Mass Index Table
Why do statistics about
overweight and obesity differ?
Prevalence Statistics
Related to Overweight and Obesity
Economic Costs Related to
Overweight and Obesity
Other Statistics Related to
Overweight and Obesity
References
About two-thirds of adults in the United States
are overweight, and almost one-third are obese,
according to data from the National Health and
Nutrition Examination Survey (NHANES) 2001 to 2004.
This fact sheet presents statistics on the
prevalence of overweight and obesity in the United
States, as well as the health risks, mortality
rates, and economic costs associated with these
conditions. To understand these statistics, it is
necessary to know how overweight and obesity are
defined and measured, something this publication
addresses. This fact sheet also explains why
statistics from different sources may not
match.
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Overweight and obesity are known
risk factors for:
- diabetes
- coronary heart disease
- high blood cholesterol
- stroke
- hypertension
- gallbladder disease
- osteoarthritis (degeneration of
cartilage and bone of joints)
- sleep apnea and other breathing
problems
- some forms of cancer (breast,
colorectal, endometrial, and
kidney)
Obesity is also associated
with:
- complications of pregnancy
- menstrual irregularities
- hirsutism (presence of excess body
and facial hair)
- stress incontinence (urine leakage
caused by weak pelvic floor
muscles)
- psychological disorders, such as
depression
- increased surgical risk
- increased mortality
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What are overweight and
obesity?
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Overweight refers to an
excess of body weight compared to set standards.
The excess weight may come from muscle, bone, fat,
and/or body water. Obesity refers specifically to
having an abnormally high proportion of body
fat.[1] A person can be overweight without being
obese, as in the example of a bodybuilder or other
athlete who has a lot of muscle. However, many
people who are overweight are also obese.
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How are weight-related health
risks determined?
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Various methods are used
to determine if someone’s weight has
increased his or her health risks. Some are based
on the relationship between height and weight;
others are based on measurements of body fat. The
most commonly used method today is the body mass
index (BMI). BMI is an index of weight adjusted
for the height of an individual.
BMI can be used to screen for both overweight
and obesity in adults. It is the measurement of
choice for many obesity researchers and other
health professionals, as well as the definition
used in most published information on overweight
and obesity. BMI is a calculation based on height
and weight, and it is not gender-specific in
adults. BMI does not directly measure percentage
of body fat, but it is a more accurate indicator
of overweight and obesity than relying on weight
alone.
BMI is calculated by dividing
a person’s weight in kilograms by height in
meters squared. The mathematical formula is
“weight (kg)/height
(m²).”
To determine BMI using pounds and inches,
multiply weight in pounds by 704.5,* divide the
result by height in inches, and then divide that
result by height in inches a second time. (You
can also use the BMI calculator at
www.nhlbisupport.com/bmi or check the
chart below.)
* The multiplier 704.5 is used by the
National Institutes of Health (NIH). Other
organizations may use a slightly different
multiplier; for example, the American Dietetic
Association suggests multiplying by 700. The
variation in outcome (a few tenths) is
insignificant.
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Body Mass
Index Table
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To use the table, find the appropriate height in
the left-hand column and then move across to a
given weight. The number at the top of the column
is the BMI at that height and weight. Pounds have
been rounded off.
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Source: Clinical Guidelines on
Identification, Evaluation, and Treatment of
Overweight and Obesity in Adults, NHLBI, September
1998
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An expert panel convened by the National Heart,
Lung, and Blood Institute (NHLBI) in cooperation
with the National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK), both part of
NIH, identified overweight as a BMI of 25 to 29.9
kg/m², and obesity as a BMI of 30 kg/m²
or greater. However, overweight and obesity are not
mutually exclusive, since people who are obese are
also overweight.[1] Defining overweight as a BMI of
25 or greater is consistent with the
recommendations of the World Health Organization
(WHO)[2] and most other countries.
Calculating BMI is simple, quick, and
inexpensive—but it does have limitations. One
problem with using BMI as a measurement tool is
that very muscular people may fall into the
“overweight” category when they are
actually healthy and fit. Another problem with
using BMI is that people who have lost muscle mass,
such as the elderly, may be in the “healthy
weight” BMI category (BMI 18.5 to 24.9) when
they actually have reduced nutritional reserves.
BMI, therefore, is useful as a screening tool for
individuals and as a general guideline to monitor
trends in the population, but by itself is not
diagnostic of an individual patient’s health
status. Further assessment of patients should be
performed to evaluate their weight status and
associated health risks.
For more information on measuring overweight and
obesity, see Weight and Waist
Measurement: Tools for Adults.
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Why do statistics about
overweight and obesity differ?
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The definitions or
measurement characteristics for overweight and
obesity have varied over time, from study to study,
and from one part of the world to another. The
varied definitions affect prevalence statistics and
make it difficult to compare data from different
studies. Prevalence refers to the total number of
existing cases of a disease or condition in a given
population at a given time. Some overweight- and
obesity-related prevalence rates are presented as
crude or unadjusted estimates, while others are
age-adjusted estimates. Unadjusted prevalence
estimates are used to present cross-sectional data
for population groups at a given point or time
period, without accounting for the effect of
different age variations among groups. For
age-adjusted rates, statistical procedures are used
to remove the effect of age differences when
comparing two or more populations at one point in
time, or one population at two or more points in
time. Unadjusted estimates and age-adjusted
estimates will yield slightly different values.
Previous studies in the United States have used
the 1959 or the 1983 Metropolitan Life Insurance
tables of desirable weight-for-height as the
reference for overweight.[3] More recently, many
Government agencies and scientific health
organizations have estimated overweight using data
from a series of cross-sectional surveys called the
National Health Examination Surveys (NHES) and
NHANES. The National Center for Health Statistics
(NCHS) of the Centers for Disease Control and
Prevention (CDC) conducted these surveys. Each had
three cycles: NHES I, II, and III spanned the
period from 1960 to 1970, and NHANES I, II, and III
were conducted in the 1970s, 1980s, and early
1990s. Since 1999, NHANES has become a continuous
survey.
Many earlier reports use a statistically derived
definition of overweight from NHANES II (1976 to
1980). This definition (based on the
gender-specific 85th percentile values of BMI for
20- to 29-year-olds) is a BMI greater than or equal
to (>) 27.3 for women and 27.8 for men.
NHANES II further defines “severe
overweight” (based on 95th percentile values)
as a BMI > 31.1 for men and a BMI
> 32.2 for women.[4] Some studies round
these numbers to a whole number, which affects the
statistical prevalence. In 1995, WHO recommended a
classification for three “grades” of
overweight using BMI cutoff points of 25, 30, and
40.[5] WHO suggested an additional cutoff point of
35 and slightly different terminology in
1998.[2]
The expert panel convened by NHLBI and NIDDK
released a report in September 1998 that provided
definitions for overweight and obesity similar to
those used by WHO. The panel identified overweight
as a BMI > 25 to less than (<) 30, and
obesity as a BMI > 30. These definitions,
widely used by the Federal Government and more
frequently by the broader medical and scientific
communities, are based on evidence that health
risks increase in individuals with a BMI
> 25.
BMI cutoff points are a guide for
definitions of overweight and obesity and are
useful for comparative purposes across populations
and over time; however, the health risks associated
with overweight and obesity are on a continuum and
do not necessarily correspond to rigid cutoff
points. For example, an overweight individual with
a BMI of 29 does not acquire additional health
consequences associated with obesity simply by
crossing the BMI threshold of > 30.
However, health risks generally increase with
increasing BMI.
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Prevalence Statistics Related to
Overweight and Obesity*
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Overweight and obesity are found worldwide, and
the prevalence of these conditions in the United
States ranks high along with other developed
nations.
Below are some frequently asked questions and
answers about overweight and obesity statistics.
Data are based on NHANES 2001 to 2004. Unless
otherwise specified, the figures given represent
age-adjusted estimates. Age-adjusted estimates are
used in order to account for the age variations
among the groups being compared. Population numbers
are based on estimates from the U.S. Census
Bureau’s Current Population
Survey.
Q: How many adults age 20 and older are
overweight or obese (BMI >
25)?
A: About two-thirds of U.S.
adults are overweight or obese.[6]
All adults: 133.6 million (66 percent)
Women: 65 million (61.6 percent)
Men: 68.3 million (70.5 percent)
* The statistics presented here are based on
the following definitions unless otherwise
specified: healthy weight = BMI > 18.5 to
< 25; overweight = BMI > 25 to <
30; obesity = BMI > 30; and extreme
obesity = BMI > 40.
Q: How many adults age 20 and older are
obese (BMI > 30)?
A: Nearly one-third of U.S.
adults are obese.[6]
All adults: 63.6 million (31.4 percent)
Women: 35 million (33.2 percent)
Men: 28.6 million (29.5 percent)
Q: How many adults age 20 and older are
at a healthy weight (BMI > 18.5 through
24.9)?
A: Less than one-third of U.S.
adults are at a healthy weight.[6]
All adults: 65.4 million (32.3 percent)
Women: 38.1 million (36.1 percent)
Men: 27.4 million (28.3 percent)
Q: How has the prevalence of overweight
and obesity in adults changed over the
years?
A: The prevalence has steadily
increased over the years among both genders, all
ages, all racial and ethnic groups, all educational
levels, and all smoking levels.[7] From 1960 to
2004, the prevalence of overweight increased from
44.8 to 66 percent in U.S. adults age 20 to 74.[6]
The prevalence of obesity during this same time
period more than doubled among adults age 20 to 74
from 13.3 to 32.1 percent, with most of this rise
occurring since 1980.[6]
Q: What is the prevalence of overweight
or obesity in minorities?
A: Among women, the
age-adjusted prevalence of overweight or obesity
(BMI > 25) in racial and ethnic
minorities is higher among non-Hispanic Black and
Mexican-American women than among non-Hispanic
White women. Among men, there is little
difference in prevalence among these three groups
[6]. Sufficient data for other racial and ethnic
minorities has not yet been collected.
Non-Hispanic Black Women: 79.6 percent
Mexican-American Women: 73 percent
Non-Hispanic White Women: 57.6 percent
Non-Hispanic Black Men: 67 percent
Mexican-American Men: 74.6 percent
Non-Hispanic White Men: 71 percent
(Statistics are for populations age 20 and
older.)
Studies using this definition of overweight and
obesity provide ethnicity-specific data only for
these three racial and ethnic groups. Studies using
different BMI cutoff points derived from NHANES II
data to define overweight and obesity have reported
a high prevalence of overweight and obesity among
Hispanics and American Indians. The prevalence of
overweight and obesity in Asian Americans is lower
than in the population as a whole.[1]
Q: What is the prevalence of overweight
and obesity in children and
adolescents?
A: While there is no generally
accepted definition for obesity as
distinct from overweight in children and
adolescents, the prevalence of overweight* is
increasing for children and adolescents in the
United States. Approximately 17.5 percent of
children (age 6 to 11) and 17 percent of
adolescents (age 12 to 19) were overweight in 2001
to 2004.[6]
* Overweight is defined by the sex- and
age-specific 95th percentile cutoff points of the
2000 CDC growth charts. These revised growth
charts incorporate smoothed BMI percentiles and are
based on data from NHES II (1963 to 1965) and III
(1966 to 1970), and NHANES I (1971 to 1974), II
(1976 to 1980), and III (1988 to 1994). The CDC BMI
growth charts specifically excluded NHANES III data
for children older than 6 years.[8]
Figure 1. Overweight and Obesity, by
Age: United States, 1960-2004
Source: CDC/NCHS, Health, United States,
2006
Q: What is the mortality rate
associated with obesity?
A: Most studies show an
increase in mortality rates associated with
obesity. Individuals who are obese have a 10- to
50-percent increased risk of death from all
causes, compared with healthy weight individuals
(BMI 18.5 to 24.9). Most of the increased risk is
due to cardiovascular causes.[1] Obesity is
associated with about 112,000 excess deaths per
year in the U.S. population relative to healthy
weight individuals.[9]
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Economic Costs Related to
Overweight and Obesity
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As the prevalence of
overweight and obesity has increased in the United
States, so have related health care
costs—both direct and indirect. Direct health
care costs refer to preventive, diagnostic, and
treatment services such as physician visits,
medications, and hospital and nursing home care.
Indirect costs are the value of wages lost by
people unable to work because of illness or
disability, as well as the value of future earnings
lost by premature death.
Most of the statistics presented here represent
the economic cost of overweight and obesity in the
United States in 1995, updated to 2001 dollars.[10]
Unless otherwise noted, these statistics are
adapted from Wolf and Colditz,[11] who based their
data on existing epidemiological studies that
defined overweight and obesity as a BMI >
29. Because the prevalence of overweight and
obesity has increased since 1995, the costs today
are higher than the figures given here.
Q: What is the cost of overweight and
obesity?
A: Total Cost: $117 billion
Direct
Cost: $61 billion*
Indirect
Cost: $56 billion
*A recent study estimated annual medical
spending due to overweight and obesity (BMI
>25) to be as much as $92.6 billion in
2002 dollars—9.1 percent of U.S. health
expenditures.[12]
Q: What is the cost of lost productivity
related to overweight and obesity?
A: The cost of lost
productivity related to obesity among Americans age
17 to 64 is $3.9 billion. This value considers the
following annual numbers (for 1994):
Workdays lost: $39.3
million
Physician office visits: $62.7
million
Restricted-activity days: $239
million
Bed-days: $89.5 million
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Other Statistics Related to
Overweight and Obesity
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Q: How
physically active is the U.S.
population?
A: Only 26 percent of U.S.
adults engage in vigorous leisure-time physical
activity three or more times per week (defined as
periods of vigorous physical activity lasting 10
minutes or more). About 59 percent of adults do
no vigorous physical activity at all in their
leisure time.[13]
About 25 percent of young people (age 12 to
21) participate in light-to-moderate activity
(e.g., walking, bicycling) nearly every day.
About 50 percent regularly engage in vigorous
physical activity. Approximately 25 percent
report no vigorous physical activity, and 14
percent report no recent vigorous or
light-to-moderate physical activity.[14]
Q: What is the cost of physical
inactivity?
A: The direct cost of
physical inactivity may be as high as $24.3
billion.[15]
Q: What are the benefits of physical
activity?
A: In addition to helping
control weight, physical activity decreases the
risk of dying from coronary heart disease and
reduces the risk of developing diabetes,
hypertension, and colon cancer.[14]
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References
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[1] Clinical
Guidelines on the Identification, Evaluation, and
Treatment of Overweight and Obesity in
Adults—The Evidence Report. National
Institutes of Health, National Heart, Lung, and
Blood Institute. September 1998. Available at
www.nhlbi.nih.gov/guidelines/obesity/ob_gdlns.htm.
[2] World Health Organization. Obesity:
Preventing and managing the global epidemic. Report
of a World Health Organization Consultation on
Obesity, Geneva, 3–5 June, 1997. World Health
Organization. Geneva, 1998.
[3] Flegal KM, Carroll MD, Kuczmarski RJ,
Johnson CL. Overweight and obesity in the United
States: Prevalence and trends, 1960–1994.
International Journal of Obesity. 1998;
22:39–47.
[4] Kuczmarski RJ, Flegal KM. Criteria for
definition of overweight in transition: Background
and recommendations for the United States.
American Journal of Clinical Nutrition.
2000; 72:1074–1081.
[5] Physical status: The use and interpretation
of anthropometry. Report of a World Health
Organization Expert Committee. World Health
Organization: Geneva, 1995 (World Health
Organization Technical Report Series; 854).
[6] National Center for Health Statistics.
Chartbook on Trends in the Health of Americans.
Health, United States, 2006. Hyattsville, MD:
Public Health Service. 2006.
[7] Mokdad AH, Ford ES, Bowman BA, Dietz WH,
Vinicor F, Bales VS, Marks JS. Prevalence of
obesity, diabetes, and obesity-related health risk
factors, 2001. Journal of the American Medical
Association. 2003; 289(1):76–79.
[8] Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000
Centers for Disease Control and Prevention growth
charts for the United States: Methods and
development. National Center for Health Statistics.
Vital Health Stat 11(246). 2002.
[9] Flegal KM, Graubard BI, Williamson, DF, Gail
MH. Excess deaths associated with underweight,
overweight, and obesity. Journal of the
American Medical Association. 2005;
293(15):1861–7.
[10] Wolf AM, Manson JE, Colditz GA. The
Economic Impact of Overweight, Obesity and Weight
Loss. In: Eckel R, ed. Obesity: Mechanisms and
Clinical Management. Lippincott, Williams and
Wilkins; 2002.
[11] Wolf AM, Colditz GA. Current estimates of
the economic cost of obesity in the United States.
Obesity Research. March 1998;
6(2):97–106.
[12] Finkelstein EA, Fiebelkorn IC, Wang G.
National medical spending attributable to
overweight and obesity: How much, and who's paying?
Health Affairs Web Exclusive. 2003;
W3:219-226. Available at
http://content.healthaffairs.org/cgi/content/full/hlthaff.w3.219v1/DC1.
[13] Lethbridge-Çejku M, Vickerie J.
Summary health statistics for U.S. adults: National
Health Interview Survey, 2003. National Center for
Health Statistics. Vital Health Stat 10(225).
2005.
[14] U.S. Department of Health and Human
Services. Physical Activity and Health: A Report of
the Surgeon General. Centers for Disease Control
and Prevention. 1996.
[15] Colditz GA. Economic costs of obesity and
inactivity. Medicine & Science in Sports
& Exercise. 1999; S663–S667.
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Weight-control Information
Network
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1 WIN Way
Bethesda, MD 20892–3665
Phone: (202) 828–1025
Toll-free number:
1–877–946–4627
Fax: (202) 828–1028
Email: WIN@info.niddk.nih.gov
Internet: www.win.niddk.nih.gov
The Weight-control Information Network (WIN) is
a service of the National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK) of the
National Institutes of Health (NIH), which is the
Federal Government’s lead agency responsible
for biomedical research on nutrition and obesity.
Authorized by Congress (Public Law 103–43),
WIN provides the general public, health
professionals, the media, and Congress with
up-to-date, science-based information on weight
control, obesity, physical activity, and related
nutritional issues.
Publications produced by WIN are reviewed by
both NIDDK scientists and outside experts. This
fact sheet was also reviewed by David F.
Williamson, Ph.D., CAPT U.S. Public Health Service,
Centers for Disease Control and Prevention (CDC),
Division of Diabetes Translation; Katherine Flegal,
Ph.D., Senior Research Scientist, National Center
for Health Statistics, CDC; and Rachel
Ballard-Barbash, M.D., M.P.H., Associate Director,
Applied Research Program, National Cancer
Institute, NIH.
This publication is not copyrighted. WIN
encourages users of this fact sheet to duplicate
and distribute as many copies as desired. This fact
sheet is also available at www.win.niddk.nih.gov.
Updated May 2007
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