Number 25 n June 25, 2010
Changes in Terminology for Childhood
Overweight and Obesity
by Cynthia L. Ogden, Ph.D., Division of Health and Nutrition Examination Surveys and
Katherine M. Flegal, Ph.D., Office of the Center Director
Abstract
Introduction
A variety of different terms, metrics, and cut-off values have been used to
A variety of different terms,
describe and assess overweight and obesity in children. Body mass index (BMI)
metrics, and cut-off values have been
calculated as weight in kilograms divided by height in meters squared can be
used to describe and assess overweight
used to express weight adjusted for height. In order to account for variability by
and obesity in children (1–3). Strictly
sex and age, BMI in children is compared to sex- and age-specific reference
speaking, overweight refers to weight in
values. In the United States, the Centers for Disease Control and Prevention
excess of a weight standard, and obesity
(CDC) 2000 growth charts serve as reference values. The terminology used for
refers to excess body fatness. However,
high BMI-for-age in children in the United States to date has been based on the
because body fat is difficult to measure,
recommendation of an expert committee convened by federal agencies. This
body weight is often used as a surrogate
committee recommended the use of BMI and defined overweight as a BMI-for­
measure or indicator of obesity.
age at or above the 95th percentile of a specified reference population and the
In children, weight varies with sex
designation of ‘‘at risk for overweight’’ for BMI values between the 85th and the
and age, not only with height (4,5). BMI
95th percentiles of BMI for age. More recently, although the cut-off values and
calculated as weight in kilograms
the interpretation have not changed, changes in terminology were proposed. An
divided by height in meters squared can
American Medical Association expert committee report retained the two cut-off
be used to express weight adjusted for
values of the 85th and 95th percentiles of BMI-for-age but used different
height. To account for variability by sex
terminology, referring to BMI-for-age from the 85th up to the 95th percentile as
and age, BMI in children is compared
‘‘overweight’’ and to BMI-for-age at or above the 95th percentile as ‘‘obesity.’’
with sex- and age-specific reference
The National Center for Health Statistics (NCHS) and other CDC publications
values. In the United States, the 2000
will continue to include prevalence estimates at the 85th and 95th percentiles as
CDC 2000 charts (6) serve as reference
before but will change the terminology to use the term ‘‘overweight’’ for a
values. The CDC growth charts, issued
BMI-for-age between the 85th and 95th percentile (formerly called ‘‘at risk for
in 2000, include smoothed percentiles of
overweight’’) and the term ‘‘obesity’’ for a BMI-for-age at or above the 95th
BMI-for-age in the United States
percentile (formerly called ‘‘overweight’’).
population based on data from the 1960s
Keywords: children • obesity • overweight • definitions
and 1970s, with additional data from
1988–1994 for children under 6 years of
age.
The BMI-for-age growth chart for
boys is displayed in the Figure. The
variation in BMI with age can be seen
in the figure. For example, the median
BMI is 15.8 for an 8-year-old boy and
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
National Center for Health Statistics

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National Health Statistics Reports n Number 25 n June 25, 2010
2 to 20 years: Boys
NAME
Body mass index-for-age percentiles
RECORD #
Date
Age
Weight
Stature
BMI*
Comments
BMI
35
34
33
32
97
31
30
95
29
95th percentile
BMI
28
90
27
27
26
85
26
25
25
75
85th percentile
24
24
23
23
50
22
22
21
21
8 year old boy
15 year old boy
25
20
BMI=21 kg/m2
BMI=21 kg/m2
20
10
19
19
3
18
18
17
17
16
16
15
15
14
14
13
13
12
12
kg/m2
AGE (YEARS)
kg/m2
2
3
4
5
6
7
8

9

10

11
12

13

14
1 5

16
1 7
1 8
1 9

20



Published May 30, 2000 (modified 10/16/00).
SOURCE: Developed by the National Center for Health Statistics in collaboration with the
National Center for Chronic Disease Prevention and Health Promotion (2000).
Available from: http://www.cdc.gov/growthcharts
Figure. 2000 CDC growth chart, boys BMI-for-age, 2–19 years of age

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National Health Statistics Reports n Number 25 n June 25, 2010
Page 3
19.8 for a 15-year-old boy. A BMI value
for these children, it was recommended
indicator of obesity, because the
of 21 is above the 95th percentile for an
that they be referred to a second-level
majority of individuals with high
8-year-old boy but between the 50th and
screen, including consideration of family
weight-for-height are obese. Strictly
75th percentiles for a 15-year-old boy.
history, blood pressure, total cholesterol,
speaking, the term ‘‘obesity’’ should
The terminology used for high
large prior increment in BMI, and
be used only in the context of
BMI-for-age in children in the United
adiposity measurements, for
concern about weight. These children
States to date has been based on the
example skinfold thickness.
would be referred for the in-depth
recommendation of an expert committee
evaluation only if they were positive for
convened by federal agencies (7). The
Changes in Terminology
any of the items on the second-level
Expert Committee report (7) published
screen. The committee used the
More recently, although the cut-off
in 1994 distinguished excess weight
designation of ‘‘at risk for overweight’’
values and the interpretation have not
from excessive body fat, stating:
for BMI values between the 85th and
changed, changes in terminology have
The committee reserved the use of
the 95th percentiles of BMI for age.
been proposed. The Institute of
the term ‘‘obesity’’ for a condition
Although this is sometimes interpreted
Medicine report on ‘‘Preventing
characterized
Childhood Obesity’’ (9) retained the
by excessive body fat.
as a designation for a child who is at
95th percentile of BMI-for-age as a
Body fat is a specific concern, and
risk for becoming overweight in the
cut-off value, but changed the
a valid measure should identify the
future, that was not the original
terminology, stating that,
fattest adolescents. Nevertheless,
intention of the term. The category as
fatness cannot be measured directly
defined by the expert committee was
The committee recognizes that it
by using stature and weight.
intended to identify children who might
has been customary to use the term
Because the indexes used were
be overweight, but who should undergo
‘‘overweight’’ instead of ‘‘obese’’ to
based on body size rather than
a second-level screen (as described
refer to children with BMI values
fatness, the committee elected to
previously) to evaluate whether they
above the age- and gender-specific
define excess body mass as
should be referred for an in-depth
95th percentiles. . . . However, the
overweight, and to rely on
assessment.
term ‘‘obese’’ more effectively
additional measures to distinguish
Following these expert committee
conveys the seriousness, urgency,
those who are obese from those
recommendations, in the United States,
and medical nature of this concern
who are overweight but who may
‘‘overweight’’ was defined as a BMI at
than does the term ‘‘overweight,’’
not be obese.
or above the 95th percentile of the 2000
thereby reinforcing the importance
CDC growth charts, and ‘‘at risk for
of taking immediate action.
This committee recommended the
overweight’’ was defined as a BMI
use of BMI and defined overweight as a
Following along these lines, a
between the 85th and the 95th
BMI-for-age at or above the 95th
subsequent American Medical
percentiles. The term ‘‘obesity,’’
percentile of a specified reference
Association expert committee report
indicating excess body fatness, was not
population and felt that children who
(10) retained the two cut-off values of
used for BMI-for-age categories.
were overweight by this definition
the 85th and 95th percentiles of
A World Health Organization
should be screened for possible
BMI-for-age but used different
(WHO) Expert Committee report (8)
obesity-related conditions. The
terminology, referring to BMI-for-age
published in 1995 distinguished between
committee also noted that these values
from the 85th up to the 95th percentile
the use of the terms ‘‘overweight’’ and
were not designed to provide clinical cut
as ‘‘overweight’’ and to BMI-for-age at
‘‘obesity,’’ based on weight and height,
points, but rather to serve as screening
or above the 95th percentile as
in individuals versus in populations.
values. The committee recommendations
‘‘obesity,’’ stating that
According to this committee:
were that children and adolescents with
The compelling reasons for this
BMI values at or above the 95th
‘‘Overweight’’ is the preferred term
revision are clinical. The term
percentile of a suitable reference
for describing high weight-for­
‘‘obesity’’ denotes excess body fat
population undergo an in-depth
height. Even though there is a
more accurately and reflects the
assessment, stating that ‘‘in-depth
strong correlation between high
associated serious health risks more
assessments are required to distinguish
weight-for-height and obesity as
clearly than does the term
positively screened adolescents who are
measured by adiposity, greater lean
‘‘overweight,’’ which is not
truly obese, to identify underlying
body mass can also contribute to
recognized as a clinical term for
diagnoses and to provide a basis for
high weight-for-height. On an
high adiposity.
prescribing treatment.’’
individual basis, therefore,
The same expert committee
‘‘fatness’’ or ‘‘obesity’’ should not
As shown in Table A, the definition
considered that children with BMI
be used to describe high weight-for­
of overweight as a BMI-for-age at or
values between the 85th and 95th
height. However, on a population-
above the 95th percentile recommended
percentiles might also be overweight,
wide basis, high weight-for-height
by the 1994 report and the definition of
although with a lower probability. Thus
can be considered as an adequate
overweight recommended by the 2007

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National Health Statistics Reports n Number 25 n June 25, 2010
Table A. Changes in terminology
intermediate range of the 85th to 95th
1994 recommended
2007 recommended
percentiles of BMI-for-age have high
Body mass index category
terminology
terminology
adiposity. These data also show that the
relation between these BMI categories
BMI 85th-<95th percentile . . . . . . . . . . . . .
At risk of overweight
Overweight
and body fatness varies by racial-ethnic
BMI =>95th percentile . . . . . . . . . . . . . . .
Overweight
Obese
group (13). Comparisons by racial-
ethnic groups show that at a given BMI
NOTE: BMI is body mass index.
level, non-Hispanic black children have
lower percentage body fat than either
non-Hispanic white or Mexican-
report as a BMI-for-age between the
‘‘overweight’’ for a BMI-for-age
American children and are less likely to
85th and 95th percentiles have no
between the 85th and 95th percentiles
have high adiposity. For example
overlap.
(formerly called ‘‘at risk for
although non-Hispanic black girls have
In recognition of the importance of
overweight’’) and the term ‘‘obesity’’ for
considerably higher prevalence of
language, the 2007 report also
a BMI-for-age at or above the 95th
obesity than non-Hispanic white girls,
recommended the use of more ‘‘neutral’’
percentile (formerly called
the prevalence of high adiposity does
terms when discussing weight issues
‘‘overweight’’). The change in
not differ between the two groups. Thus,
with families, stating that ‘‘Therefore,
terminology reflects the labels used by
caution should be exercised in
the expert committee recommends the
the American Academy of Pediatrics and
interpreting comparisons of obesity
use of the clinical terms ‘overweight’
other organizations. Table B contains the
levels between racial-ethnic groups in
and ‘obesity’ for documentation and risk
estimates from the same National Health
terms of adiposity. Caution should also
assessment but the use of different terms
and Nutrition Examination Survey
be exercised in interpreting intermediate
in the clinician’s office, to avoid an
(NHANES) years comparing the two
BMI levels between the 85th and 95th
inference of judgment or repugnance.’’
sets of terms.
percentiles in terms of excess body fat,
The term ‘‘obesity’’ will be used for
particularly for non-Hispanic black
NCHS Publications
the prevalence of BMI-for-age at or
children.
above the 95th percentile. However, as
Recognizing the imperfections of
Publications from NCHS have
noted by the expert committee, obesity
BMI in classifying adiposity, the
included prevalence estimates based on
strictly speaking refers to excess body
Surgeon General’s recent ‘‘Vision for a
the 85th and 95th percentiles of
fat and not to high BMI-for-age. Not all
Healthy and Fit Nation’’ (14) states that:
BMI-for-age in children (for example
children at the BMI-for-age level
(11,12)). The terminology employed in
labeled ‘‘obesity’’ necessarily have
Assessing if a child is at a healthy
these publications followed the Expert
excess body fat and some children
weight is complex. While BMI is
Committee recommendation from 1994.
below that level may have excess body
often utilized, clinical assessment
The prevalence of BMI-for-age at or
fat. For children, there is no precise
and other markers should be
above the 95th percentile was
widely accepted definition of obesity in
considered when determining a
considered ‘‘overweight’’ and those
terms of body fatness. Research using
child’s overall health and
between the 85th and 95th percentiles
NHANES data on BMI and body
development. . . . Children and
were labeled ‘‘at risk for overweight.’’
fatness show that according to a
adolescents with a BMI at or above
NCHS and other CDC publications
plausible range of possible cut-off
the sex- and age-specific 95th
will continue to include prevalence
values for high adiposity, the majority of
percentile of this reference
estimates at the 85th and 95th
children with BMI at or above the 95th
population are often considered
percentiles as before but will change the
percentile have high adiposity and less
obese, and those with a BMI
terminology to use the term
than one-half of children in the
between the 85th and 94th
percentiles are often considered
Table B. Prevalence (standard error) of high body mass index (BMI): United States,
overweight. Although these cut-off
children 2-19 years
points are not diagnostic criteria,
Definition
2005–2006
2007–2008
elevated BMI among children most
often indicates increased risk for
BMI-for-age >= 95th percentile1
future adverse health outcomes
Old terminology: Overweight . . . . . . . . . . . . . . . . . . . . . . .
15.5 (1.3)
16.9 (1.3)
and/or development of disease.
New terminology: Obese . . . . . . . . . . . . . . . . . . . . . . . . .
15.5 (1.3)
16.9 (1.3)
BMI-for-age >= 85th percentile1
BMI-for-age categories continue to
Old terminology: At risk for overweight or overweight . . . . . . . .
30.1 (1.6)
31.7 (1.2)
be valuable tools for population
New terminology: Overweight or obese . . . . . . . . . . . . . . . .
30.1 (1.6)
31.7 (1.2)
surveillance. It is important to note what
definitions of BMI categories are being
1On the sex-specific CDC growth charts.
SOURCE:
used
CDC/NCHS, National Health and Nutrition Examination Survey.
in a given report to avoid

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National Health Statistics Reports n Number 25 n June 25, 2010
Page 5
confusion, particularly in the meaning of
10. Krebs NF, Himes JH, Jacobson D.
the term ‘‘overweight,’’ which has a
Nicklas TA, Guilday P, Styne D:
different meaning in the new
Assessment of child and adolescent
terminology than in the old terminology.
overweight and obesity. Pediatr 120
When
Suppl 4:S193–S228. 2007.
reporting trends over time, the
11. National Center for Health Statistics.
new terminology will be applied to data
Health, United States, 2008 With
from past surveys as well as to current
Chartbook. Hyattsville, Maryland.
surveys, so that the definitions within a
2009.
given report will be consistent across all
12. Ogden CL, Flegal KM, Carroll MD,
surveys and not vary by survey. It is
Johnson CL. Prevalence and trends
important when comparing estimates
in overweight among United States
from different reports to assure that the
children and adolescents, 1999–2000.
definitions used are the same across
JAMA 288:1728–32. 2002.
reports.
13. Flegal KM, Ogden CL, Yanovski JA,
Freedman DS. High adiposity and
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et al. 2000 CDC growth charts for
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11(246). 2002.
7. Himes JH, Dietz WH. Guidelines for
overweight in adolescent preventive
services: Recommendations from an
expert committee. The Expert
Committee on Clinical Guidelines for
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8. World Health Organization. Physical
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National Health Statistics Reports n Number 25 n June 25, 2010
Suggested citation
Copyright information
National Center for Health Statistics
Ogden CL, Flegal KM. Changes in terminology
All material appearing in this report is in the
Edward J. Sondik, Ph.D., Director
for childhood overweight and obesity. National
public domain and may be reproduced or
Jennifer H. Madans, Ph.D., Associate Director
health statistics reports; no 25. Hyattsville,
copied without permission; citation as to
for Science
MD: National Center for Health Statistics.
source, however, is appreciated.
Division of Health and Nutrition
2010.
Examination Surveys
Clifford L. Johnson, M.S.P.H.,Director
U.S. DEPARTMENT OF
HEALTH & HUMAN SERVICES
FIRST CLASS
Centers for Disease Control and Prevention
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CS213222
T36859 (06/2010)

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Document Outline

• Abstract
• Introduction
• Changes in Terminology
• NCHS Publications
• References

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