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

A variety of different terms, metrics, and cut-off values have been used to

describe and assess overweight and obesity in children. Body mass index (BMI)

calculated as weight in kilograms divided by height in meters squared can be

used to express weight adjusted for height. In order to account for variability by

sex and age, BMI in children is compared to sex- and age-specific reference

values. In the United States, the Centers for Disease Control and Prevention

(CDC) 2000 growth charts serve as reference values. The terminology used for

high BMI-for-age in children in the United States to date has been based on the

recommendation of an expert committee convened by federal agencies. This

committee recommended the use of BMI and defined overweight as a BMI-forage at or above the 95th percentile of a specified reference population and the

designation of ‘‘at risk for overweight’’ for BMI values between the 85th and the

95th percentiles of BMI for age. More recently, although the cut-off values and

the interpretation have not changed, changes in terminology were proposed. An

American Medical Association expert committee report retained the two cut-off

values of the 85th and 95th percentiles of BMI-for-age but used different

terminology, referring to BMI-for-age from the 85th up to the 95th percentile as

‘‘overweight’’ and to BMI-for-age at or above the 95th percentile as ‘‘obesity.’’

The National Center for Health Statistics (NCHS) and other CDC publications

will continue to include prevalence estimates at the 85th and 95th percentiles as

before but will change the terminology to use the term ‘‘overweight’’ for a

BMI-for-age between the 85th and 95th percentile (formerly called ‘‘at risk for

overweight’’) and the term ‘‘obesity’’ for a BMI-for-age at or above the 95th

percentile (formerly called ‘‘overweight’’).

Keywords: children • obesity • overweight • definitions

Introduction

A variety of different terms,

metrics, and cut-off values have been

used to describe and assess overweight

and obesity in children (1–3). Strictly

speaking, overweight refers to weight in

excess of a weight standard, and obesity

refers to excess body fatness. However,

because body fat is difficult to measure,

body weight is often used as a surrogate

measure or indicator of obesity.

In children, weight varies with sex

and age, not only with height (4,5). BMI

calculated as weight in kilograms

divided by height in meters squared can

be used to express weight adjusted for

height. To account for variability by sex

and age, BMI in children is compared

with sex- and age-specific reference

values. In the United States, the 2000

CDC 2000 charts (6) serve as reference

values. The CDC growth charts, issued

in 2000, include smoothed percentiles of

BMI-for-age in the United States

population based on data from the 1960s

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 
2 to 20 years: Boys NAME 

Body mass index-for-age percentiles RECORD # 

Date Age Weight Stature BMI* Comments 

35 

BMI 

34 

33 

97

32 

30 

31 

95 

29 

BMI 28

90 

26 

27 

85 26 

27 

25 25 

24 

75 

24 

23 23 

22 

50 

22 

21 21 

20 8 year old boy 15 year old boy 25 

20 

19 

BMI=21 kg/m2 BMI=21 kg/m2 

10 

19 

18 3 18 

17 17 

15 

16 

15 

16 

14 14 

13 

12 

13 

12 

kg/m2 AGE Y( EARS) kg/m2 

95th percentile 

85th percentile 

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 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

Page 2 National Health Statistics Reports n Number 25 n June 25, 2010

Figure. 2000 CDC growth chart, boys BMI-for-age, 2–19 years of age
National Health Statistics Reports n Number 25 n June 25, 2010 Page 3

19.8 for a 15-year-old boy. A BMI value

of 21 is above the 95th percentile for an

8-year-old boy but between the 50th and

75th percentiles for a 15-year-old boy.

The terminology used for high

BMI-for-age in children in the United

States to date has been based on the

recommendation of an expert committee

convened by federal agencies (7). The

Expert Committee report (7) published

in 1994 distinguished excess weight

from excessive body fat, stating:

The committee reserved the use of

the term ‘‘obesity’’ for a condition

characterized by excessive body fat.

Body fat is a specific concern, and

a valid measure should identify the

fattest adolescents. Nevertheless,

fatness cannot be measured directly

by using stature and weight.

Because the indexes used were

based on body size rather than

fatness, the committee elected to

define excess body mass as

overweight, and to rely on

additional measures to distinguish

those who are obese from those

who are overweight but who may

not be obese.

This committee recommended the

use of BMI and defined overweight as a

BMI-for-age at or above the 95th

percentile of a specified reference

population and felt that children who

were overweight by this definition

should be screened for possible

obesity-related conditions. The

committee also noted that these values

were not designed to provide clinical cut

points, but rather to serve as screening

values. The committee recommendations

were that children and adolescents with

BMI values at or above the 95th

percentile of a suitable reference

population undergo an in-depth

assessment, stating that ‘‘in-depth

assessments are required to distinguish

positively screened adolescents who are

truly obese, to identify underlying

diagnoses and to provide a basis for

prescribing treatment.’’

The same expert committee

considered that children with BMI

values between the 85th and 95th

percentiles might also be overweight,

although with a lower probability. Thus

for these children, it was recommended

that they be referred to a second-level

screen, including consideration of family

history, blood pressure, total cholesterol,

large prior increment in BMI, and

concern about weight. These children

would be referred for the in-depth

evaluation only if they were positive for

any of the items on the second-level

screen. The committee used the

designation of ‘‘at risk for overweight’’

for BMI values between the 85th and

the 95th percentiles of BMI for age.

Although this is sometimes interpreted

as a designation for a child who is at

risk for becoming overweight in the

future, that was not the original

intention of the term. The category as

defined by the expert committee was

intended to identify children who might

be overweight, but who should undergo

a second-level screen (as described

previously) to evaluate whether they

should be referred for an in-depth

assessment.

Following these expert committee

recommendations, in the United States,

‘‘overweight’’ was defined as a BMI at

or above the 95th percentile of the 2000

CDC growth charts, and ‘‘at risk for

overweight’’ was defined as a BMI

between the 85th and the 95th

percentiles. The term ‘‘obesity,’’

indicating excess body fatness, was not

used for BMI-for-age categories.

A World Health Organization

(WHO) Expert Committee report (8)

published in 1995 distinguished between

the use of the terms ‘‘overweight’’ and

‘‘obesity,’’ based on weight and height,

in individuals versus in populations.

According to this committee:

‘‘Overweight’’ is the preferred term

for describing high weight-forheight. Even though there is a

strong correlation between high

weight-for-height and obesity as

measured by adiposity, greater lean

body mass can also contribute to

high weight-for-height. On an

individual basis, therefore,

‘‘fatness’’ or ‘‘obesity’’ should not

be used to describe high weight-forheight. However, on a populationwide basis, high weight-for-height

can be considered as an adequate

indicator of obesity, because the

majority of individuals with high

weight-for-height are obese. Strictly

speaking, the term ‘‘obesity’’ should

be used only in the context of

adiposity measurements, for

example skinfold thickness.

Changes in Terminology

More recently, although the cut-off

values and the interpretation have not

changed, changes in terminology have

been proposed. The Institute of

Medicine report on ‘‘Preventing

Childhood Obesity’’ (9) retained the

95th percentile of BMI-for-age as a

cut-off value, but changed the

terminology, stating that,

The committee recognizes that it

has been customary to use the term

‘‘overweight’’ instead of ‘‘obese’’ to

refer to children with BMI values

above the age- and gender-specific

95th percentiles. . . . However, the

term ‘‘obese’’ more effectively

conveys the seriousness, urgency,

and medical nature of this concern

than does the term ‘‘overweight,’’

thereby reinforcing the importance

of taking immediate action.

Following along these lines, a

subsequent American Medical

Association expert committee report

(10) retained the two cut-off values of

the 85th and 95th percentiles of

BMI-for-age but used different

terminology, referring to BMI-for-age

from the 85th up to the 95th percentile

as ‘‘overweight’’ and to BMI-for-age at

or above the 95th percentile as

‘‘obesity,’’ stating that

The compelling reasons for this

revision are clinical. The term

‘‘obesity’’ denotes excess body fat

more accurately and reflects the

associated serious health risks more

clearly than does the term

‘‘overweight,’’ which is not

recognized as a clinical term for

high adiposity.

As shown in Table A, the definition

of overweight as a BMI-for-age at or

above the 95th percentile recommended

by the 1994 report and the definition of

overweight recommended by the 2007
Page 4 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

BMI 85th-<95th percentile ............. At risk of overweight Overweight
 

BMI =>95th percentile ............... Overweight Obese
 

NOTE: BMI is body mass index.

report as a BMI-for-age between the

85th and 95th percentiles have no

overlap.

In recognition of the importance of

language, the 2007 report also

recommended the use of more ‘‘neutral’’

terms when discussing weight issues

with families, stating that ‘‘Therefore,

the expert committee recommends the

use of the clinical terms ‘overweight’

and ‘obesity’ for documentation and risk

assessment but the use of different terms

in the clinician’s office, to avoid an

inference of judgment or repugnance.’’

NCHS Publications

Publications from NCHS have

included prevalence estimates based on

the 85th and 95th percentiles of

BMI-for-age in children (for example

(11,12)). The terminology employed in

these publications followed the Expert

Committee recommendation from 1994.

The prevalence of BMI-for-age at or

above the 95th percentile was

considered ‘‘overweight’’ and those

between the 85th and 95th percentiles

were labeled ‘‘at risk for overweight.’’

NCHS and other CDC publications

will continue to include prevalence

estimates at the 85th and 95th

percentiles as before but will change the

terminology to use the term

‘‘overweight’’ for a BMI-for-age

between the 85th and 95th percentiles

(formerly called ‘‘at risk for

overweight’’) and the term ‘‘obesity’’ for

a BMI-for-age at or above the 95th

percentile (formerly called

‘‘overweight’’). The change in

terminology reflects the labels used by

the American Academy of Pediatrics and

other organizations. Table B contains the

estimates from the same National Health

and Nutrition Examination Survey

(NHANES) years comparing the two

sets of terms.

The term ‘‘obesity’’ will be used for

the prevalence of BMI-for-age at or

above the 95th percentile. However, as

noted by the expert committee, obesity

strictly speaking refers to excess body

fat and not to high BMI-for-age. Not all

children at the BMI-for-age level

labeled ‘‘obesity’’ necessarily have

excess body fat and some children

below that level may have excess body

fat. For children, there is no precise

widely accepted definition of obesity in

terms of body fatness. Research using

NHANES data on BMI and body

fatness show that according to a

plausible range of possible cut-off

values for high adiposity, the majority of

children with BMI at or above the 95th

percentile have high adiposity and less

than one-half of children in the

Table B. Prevalence (standard error) of high body mass index (BMI): United States,

children 2-19 years

Definition 2005–2006 2007–2008

BMI-for-age >= 95th percentile1
 

Old terminology: Overweight ....................... 
 

New terminology: Obese ......................... 
 

BMI-for-age >= 85th percentile1
 

Old terminology: At risk for overweight or overweight ........ 
 

New terminology: Overweight or obese ................ 
 

1

On the sex-specific CDC growth charts.
 

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

15.5 (1.3) 16.9 (1.3)

15.5 (1.3) 16.9 (1.3)

30.1 (1.6) 31.7 (1.2)

30.1 (1.6) 31.7 (1.2)

relation between these BMI categories

and body fatness varies by racial-ethnic

group (13). Comparisons by racialethnic groups show that at a given BMI

level, non-Hispanic black children have

lower percentage body fat than either

non-Hispanic white or MexicanAmerican children and are less likely to

have high adiposity. For example

although non-Hispanic black girls have

considerably higher prevalence of

obesity than non-Hispanic white girls,

the prevalence of high adiposity does

not differ between the two groups. Thus,

caution should be exercised in

interpreting comparisons of obesity

levels between racial-ethnic groups in

terms of adiposity. Caution should also

be exercised in interpreting intermediate

BMI levels between the 85th and 95th

percentiles in terms of excess body fat,

particularly for non-Hispanic black

children.

Recognizing the imperfections of

BMI in classifying adiposity, the

Surgeon General’s recent ‘‘Vision for a

Healthy and Fit Nation’’ (14) states that:

Assessing if a child is at a healthy

weight is complex. While BMI is

often utilized, clinical assessment

and other markers should be

considered when determining a

child’s overall health and

development. . . . Children and

adolescents with a BMI at or above

the sex- and age-specific 95th

percentile of this reference

population are often considered

obese, and those with a BMI

between the 85th and 94th

percentiles are often considered

overweight. Although these cut-off

points are not diagnostic criteria,

elevated BMI among children most

often indicates increased risk for

future adverse health outcomes

and/or development of disease.

BMI-for-age categories continue to

be valuable tools for population

surveillance. It is important to note what

definitions of BMI categories are being

used in a given report to avoid
National Health Statistics Reports

n Number 25n June 25, 2010	 Page5

confusion, particularly in the meaning of

the term ‘‘overweight,’’ which hasa

different meaning in the new

terminology than in the old terminology.

When reporting trends over time, the

new terminology will be applied to data

from past surveys as well as to current

surveys, so that the definitions withina

given report will be consistent across all

surveys and not vary by survey. It is

important when comparing estimates

from different reports to assure that the

definitions used are the same across

reports.

References

1.Flegal KM, Tabak CJ, Ogden CL.

Overweight in children: definitions

and interpretation. Health Educ Res

21:755–760. 2006.

2.Guillaume M. Defining obesity in

childhood: Current practice 2. AmJ

Clin Nutr 70:126S–30S. 1999.

3.Neovius M, Linne Y, Barkeling B,

Rossner S. Discrepancies between

classification systems of childhood

obesity. Obes Rev 5:105–14. 2004.

4.Dietz WH, Robinson TN. Use of the

body mass index (BMI) asa measure

of overweight in children and

adolescents.J Pediatr 132:191–3.

1998.

5.Dietz WH, Bellizzi MC.

Introduction: The use of body mass

index to assess obesity in children.

AmJ Clin Nutr 70:123S–5S. 1999.

6.Kuczmarski RJ, Ogden CL, Guo SS,

et al. 2000 CDC growth charts for

the United States: Methods and

development. National Center for

Health Statistics, Vital Health Stat

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

Overweight in Adolescent Preventive

Services. AmJ Clin Nutr 59:307–16.

1994.

8.World Health Organization. Physical

status: The use and interpretation of

anthropometry. Geneva, Switzerland,

WHO. WHO Techincal Report Series

854. 1995.

9.Koplan JP, Liverman CT, Kraak VI.

Preventing childhood obesity: Health

in the balance: executive summary.J

Am Diet Assoc 105:131–8. 2005.

10. Krebs NF, Himes JH, Jacobson D.

Nicklas TA, Guilday P, Styne D:

Assessment of child and adolescent

overweight and obesity. Pediatr 120

Suppl 4:S193–S228. 2007.

11. National Center for Health Statistics.

Health, United States, 2008 With

Chartbook. Hyattsville, Maryland.

2009.

12. Ogden CL, Flegal KM, Carroll MD,

Johnson CL. Prevalence and trends

in overweight among United States

children and adolescents, 1999–2000.

JAMA 288:1728–32. 2002.

13. Flegal KM, Ogden CL, Yanovski JA,

Freedman DS. High adiposity and

high body mass index-for-age in U.S.

children and adolescents overall and

by race-ethnic group. AmJ Clin Nutr

91:1020–6. 2010.

14. U.S. Department of Health and

Human Services. The Surgeon

General’s Vision fora Healthy and

Fit Nation. Rockville, Maryland, U.S.

Department of Health and Human

Services, Office of the Surgeon

General. 2010.
Page 8 National Health Statistics Reports n Number 25 n June 25, 2010

Suggested citation

Ogden CL, Flegal KM. Changes in terminology

for childhood overweight and obesity. National

health statistics reports; no 25. Hyattsville,

MD: National Center for Health Statistics.

2010.

Copyright information

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source, however, is appreciated.

National Center for Health Statistics

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Jennifer H. Madans, Ph.D., Associate Director
 

for Science
 

Division of Health and Nutrition
 

Examination Surveys
 

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HEALTH & HUMAN SERVICES

Centers for Disease Control and Prevention

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