Establishing a standard definition for child overweight and obesity worldwide: international survey
BMJ 2000; 320 doi: https://doi.org/10.1136/bmj.320.7244.1240 (Published 06 May 2000) Cite this as: BMJ 2000;320:1240
All rapid responses
Rapid responses are electronic comments to the editor. They enable our users to debate issues raised in articles published on bmj.com. A rapid response is first posted online. If you need the URL (web address) of an individual response, simply click on the response headline and copy the URL from the browser window. A proportion of responses will, after editing, be published online and in the print journal as letters, which are indexed in PubMed. Rapid responses are not indexed in PubMed and they are not journal articles. The BMJ reserves the right to remove responses which are being wilfully misrepresented as published articles or when it is brought to our attention that a response spreads misinformation.
From March 2022, the word limit for rapid responses will be 600 words not including references and author details. We will no longer post responses that exceed this limit.
The word limit for letters selected from posted responses remains 300 words.
Dear Sir,
Childhood obesity is a new challenge in both the developed and developing world. However, the data on prevalence in various populations in children and adolescence were very much lacking because there was no simple and good cut off for the measurement of obesity in childhood, unlike in adult.
Dr. TJ Cole and colleagues (BMJ, 6 May, 2000) proposed a standard definition for child overweight and obesity, basing on six large international growth surveys, Hong Kong being one of these(1).
As one of the workers of the Hong Kong growth survey, I would like to congratulate the authors making a very good point that any such cut off should coincide with that of adult at age 18. However, there are three points that I would like to raise for further discussion.
First, children are unique in their complicated issue of growth so that description of their weight and height is usually age specific. Body fat accumulation has four physiological phases(2) and obesity is usually an exaggeration of the prepubertal phase. Paediatricians who look after obese children are familiar with a typical information given by parents that 'their child put on weight rapidly after the age of 5 years.' That is why obesity is mainly a problem of childhood and adolescence but rarely of infants and toddlers. It is hence absurd to believe that throughout childhood and adolescence the prevalence of obesity is the same.Therefore, using a uniform centile line across the whole age range of childhood to define obesity is not scientific and can be very misleading. e.g. any infant, toddler or preschooler who has BMI above the 90th centiles might have been advised to have weight control when they were in fact normal.
The Hong Kong growth survey was performed in 1993, basing on 25,000 individuals. 120% median weight for height was used as cut off for obesity(3). Children who were defined obese do look obese by observation. If 120% median BMI was used as cut off for obesity, the prevalence was also quite close, particularly before puberty (Fig.1). The knowledge of the varied prevalence between 0-18 years is also important in designing strategy for the community health services. One obvious deduction is that it is important to help all toddlers and preschoolers to establish healthy diet and life style even before many of them become obese. Whereas for school children, it is important to design exercise programme and healthy meals at school in addition to educating the parents about healthy life style.
Second, the argument for using an international reference for growth assessment in childhood is still ongoing. Studies have shown that Asians develop morbidity related to obesity, such as diabetes mellitus, hypertension and hypercholesterolemia, at a lower BMI compared to the Caucasians (4). Recently WHO recommended a cut off BMI index for Asians: >23-24.9 as overweight and > 25 as obese. For the Caucasians these would be : > 25-29.9 as overweight and > 30 as obese. If Asians were to use the international reference and cut off, then they would easily underestimate the severity of the problem of obesity. If national or ethnically appropriate reference for defining obesity were used we can still compare the prevalence of obesity between populations, be it adults or children.
Last, in the childhood population, the differentiation between overweight and obesity may not have much implication in the management, unlike the adults. Therefore, if 120% median BMI was used for Hong Kong, then at 18 years it would approximate that of 25.
Unless there is a better reason to change the cut off reference, I think Hong Kong can still stick to the use of 120% median BMI or 120% median weight for height. The latter is much more convenient in the clinic setting and the local Student Health Services has been using it to monitor the progression of the problem of childhood obesity since it's establishment in 1997.
Yours sincerely,
Dr. Sophie Leung
Centre for Nutritional Studies,
The Chinese University of Hong Kong
Corresponding address:
Dr. Sophie Leung,Sophie Leung,
Shop G32, MetroCity Phase III,
8, Mau Yip Road,
Tseung Kwan O, Hong Kong
Email: ssfleung@netvigator.com
References:
1. Leung SSF, Cole TJ, Tse LY, Lau JYF. Body mass index reference curves for Chinese children. Ann of Hum Bio 1998;25(2):169-74.
2. Leung SSF, Chan SM, Lee WTK, Davies DP. Growth and nutrition of Hong Kong children aged 0-7 years. J. Paed Child Heath 2000;36:56-65.
3. Leung SSF, Lau JTF, Tse LY, Oppenheimer SJ. Weight for age and weight for height reference for Hong Kong children birth -18 years. Aust J. Paediatrics 1996;32:103-9.
4. Ko GTC, Chan JCN, Cockram CS, Woo J. Prediction of hypertension, diabetes, dyslipidaemia or albuminuria using simple anthropometric indexes in Hong Kong Chinese. Int J Obes. 1999;23:1136-42.
5. The Asia Pacific Perspective: redefining obesity and its treatment. Feb 2000. Health Communications Australia Pty Limited.
Competing interests: No competing interests
Is the proposed standard definition for child overweight and obesity
internationally acceptable?
The issue of internationally acceptable definitions of overweight and
obesity is discussed by Cole et. al. (1). The article is a much welcome
contribution to the ongoing debate. However, it also raises some
questions:
1) Why did the authors use for constructing the average percentile
curves based on 6 data sets only two European studies (Great Britain and
the Netherlands)? What selection criteria were used that disqualified
other existing data sets?
2) The assumption that in a population of 18-year olds, there are 10
per cent of individuals with BMI values above 25 and 3 per cent with BMI
values above 30 can be also disputed. If this were the case, we would have
to conclude that in the European population of 18 year old individuals
only 0.9 per cent of overweight and 0.3 per cent of obese can be found,
whereas in populations of the United States and Hong Kong these values
would be 3.3 and 3.1 per cent, respectively.
The results of the 5th Nationwide Anthropological Survey of children
and adolescents from 0-18-years of age, carried out in the Czech Republic
in 1991, seem to strongly indicate that the proposed definitions are too
tolerant for the European population. The survey collected information on
basic anthropometric characteristics of 86 846 individuals from 0 - 18
years old (2, 3). Empirical percentiles was smoothed (using moving
average) and resulting curves were plotted. Using the cut off points
suggested by Cole (1), the percentage of Czech children who would fall
into a category of overweight or obese was calculated.
Results clearly shows that values of the 90th percentile do not vary
significantly from the values proposed by Cole. However, values for the
97th percentile are significantly lower for the Czech population. While
the values of the 97th percentile reach 27.7 in boys and 28.2 in girls,
respectively, the value suggested by Cole, to ensure a smooth link with
values for the adult population, is BMI 30. The above mentioned results
and comparisons imply that the proposed cut off points underestimate
considerably the actual prevalence of obesity. Instead of the expected 3
per cent prevalence of obesity, we find only 1 per cent of obese
individuals.
In conclusion, we believe that a starting point for developing values
for the 90th and 97th percentile in 18-year olds should be based on
analysis of growth studies from more that two European countries.
This research is supported by Grant Agency of MofH CR, grant no. 5158-3
References
1 Cole TJ, Belizzi MC, Flegal KM, Dietz WH: Establishing a standard
definition for child overweight and obesity worldwide: international
survey. BMJ 2000, 320:1240-3.
2 Vignerová J., Bláha P.: The Growth of the Czech Child during the past 40
Years. In: Bodzár, B.É., and Suzanne, C. (Eds) Secular Growth Changes in
Europe, Eotwos Univ. Press, Budapest, 1998. pp. 93-107.
3 Vignerová J., Lhotská L., Bláha P., Roth Z.: Growth of Czech Child
Population 0-18 Years Compared to the World Health Organisation Growth
Reference, American Journal of Human Biology, 9:459-468, 1997.
Competing interests: No competing interests
Re: Reanalysis suggests that the new definition for child obesity has questionable validity in puber
This is not a new letter but additional information only.
In my previous letter, I quoted a article (in press).
The article has now been published and it may be of interest (as a source
of data for reanalysis:
Reference:
Kinra S, Nelder RP, Lewendon GJ. Deprivation and childhood obesity: a
cross-sectional study of 20 973 children in Plymouth, United Kingdom. J
Epidemiol Community Health 2000;54:456-60.
Thank you
Sanjay Kinra
Competing interests: No competing interests
EDITOR- Cole at al (1) suggest a new definition of child obesity
which they argue is less arbitrary and potentially more international. It
is unclear how pooling data from six non-representative countries and
linking the cut-off to a certain adult cut-off value, which was
arbitrarily defined in itself, serves either of the two purposes greatly.
If anything, it muddies the waters a bit as one of the advantages of using
cut-offs based on one population, however inappropriate, is that it allows
the user to predict the direction of the bias, which becomes harder with a
mixed population.
The authors argue that 'the sensitivity of the curve to the timing of
puberty may affect performance of the cut-off points where puberty is
appreciably delayed, although differences of less than two years are
unlikely to make much difference'. To test this claim on the behalf of the
authors, I have compared the standard definition used in the UK, which was
also provided by Cole, (BMI above the 98th centile of UK reference) (2) to
the new definition using a local data set of 20,802 children, aged 5.5 -
14 years, from Plymouth, UK (3). Overall, there were 5% (n=1035) children
considered obese by the old definition as against 3.0% (n=614) by the new
definition; of these 611 children were classified obese by both the
definitions (kappa statistic=0.73; p<_0.001. most="most" of="of" this="this" difference="difference" in="in" classification="classification" however="however" was="was" manifest="manifest" the="the" pubertal="pubertal" age="age" group="group" see="see" table="table" _1.="_1." p="p"/>
| Age quartiles (years) | BOYS | GIRLS | BOTH SEXES | |||
| Old def. | New def. | Old def. | New def. | Old def. | New def. | |
| 5.3-7.1 | 3.8% (104) | 2.2% (60) | 3.2% (80) | 3.1% (78) | 3.5% (184) | 2.7% (138) |
| 7.1-8.9 | 5.0% (131) | 2.8% (74) | 3.8% (97) | 3.3% (84) | 4.4% (228) | 3.0% (158) |
| 8.9-11.7 | 5.7% (154) | 2.7% (74) | 5.0% (125) | 3.2% (83) | 5.4% (279) | 3.0% (157) |
| 11.7-14.1 | 6.2% (161) | 2.1% (53) | 7.0% (183) | 4.1% (108) | 6.6% (344) | 3.1% (161) |
| ALL AGES | 5.2% (550) | 2.5% (261) | 4.8% (485) | 3.5% (353) | 5.0% (1035) | 3.0% (614) |
| * All differences significant at 5% level (chi2 test p | ||||||
Significant differences in the timing of the pubertal onset between
populations are well known (4). A key determinant of variation in pubertal
timing between populations is socio-economic status and five out of the
six countries (Brazil excluded) have Gross Domestic Products (GDP's) way
above most of the African and Asian countries. Most childhood obesity is
manifest in puberty and it is exactly at this stage that the new
definition is likely to misclassify. Definitions such as these, produced
by respected authorities, often get accepted very quickly without
sufficient debate. Over time, the word 'international' sticks and gives
people the impression of universality; long after the original baseline
population gets forgotten. The authors make the time immemorial
misassumption of regarding children as little adults and trying to extend
the relatively greater homogeneity of adult populations to children.
Inconvenient as it may be, we will just have to learn to live with the
quirks of childhood growth, instead of trying to fudge them in one all
encompassing international definition.
Sanjay Kinra specialist registrar in public health medicine
South & West Devon Health Authority, Dartington TQ9 6JE
1. Cole TJ, Bellizzi MC, Flegal K, Dietz WH. Establishing a standard
definition for child overweight and obesity worldwide: international
survey. BMJ 2000;320:1240-3.
2. Cole TJ, Freeman JV, Preece MA. Body mass index reference curves for
the UK, 1990. Arch Dis Child 1995;73:25-9.
3. Kinra S, Nelder R, Lewendon G. Deprivation and childhood obesity: a
cross-sectional study of 20,973 children in Plymouth, UK. The Journal of
Epidemiology & Community Health (in press).
4. Proos LA. Anthropometry in adolescence - secular trends, adoption,
ethnic and environmental differences. Hormone Res 1993;39 Suppl 3:18-24.
Competing interests: Table 1. Numbers (in brackets) and proportions of children consideredobese by old and new definitions (def.)*
To the Editor: The impending global climate change would adversely
affect innumerable patients of diabetes mellitus globally. The climate
change would interfere with diagnostic techniques and therapeutic
interventions. Insulin, the sheet anchor of therapeutic intervention, has
to be stored in powered form at -20oC and in injection form at 2-8oC. To
maintain biological activity, injections have never to be frozen during
storage1. Furthermore, oral hypoglycemic, suplhonylureas and biguanids are
to be stored in controlled temperature of 15 to 25 or 30oC. Any
inadvertent exposure to higher temperatures or accidental freezing could
be disastrous for insulin potency.
A new record for global temperature was established during July 1998 when
the average global temperature reached was 15.5oC, while July 1998 was the
hottest month in past 120 years2. High temperature if accompanied by high
humidity would involve enormous heat transmission to insulin and oral
antidiabetic preparations prescribed for patients with diabetes mellitus.
During the 1995 heat wave in Chicago, the maximum temperature reached was
40oC, but the heat-index, an estimate of radiative and evaporative
transfer of heat was 48.3oC3. Moreover, in developing countries, poor
electricity supplies that disrupt the working of appliances designed to
maintain temperatures at appropriate level4, accompany heat waves.
Furthermore, wars, civil unrest, and natural distress disrupt power
generation facilities in large metropolitan towns for a long period5.
Insulin injections with a mandate to be never frozen and like the vials of
hepatitis B vaccine might be frozen accidentally. In the Northern
territory of Australia, continuous monitoring of 144 vaccine vials
unveiled that during transport to various immunization centers, 47.5%
vials had been exposed to temperature of -3oC or lower6. Similar handling
could be possible with insulin also. Potency of oral hypoglycemic agents,
with desired temperature maxima of 25 or 30oC, might also resemble the
data on potency of assay on other therapeutics with identical storage
temperature requirements.
During the assay of field samples of chloroquine, amoxycillin,
tetracycline, cotrimoxozole and ampiclox in Nigeria and Thailand, 36.5%
samples were found to be substandard. Moreover, in six samples of
chloroquine, there was no active ingredient left7. The scourge of poor
quality antidiabetic therapeutics needs attention by quantification of
field samples for active ingredients and their stabilization against
adverse environment.
Addition of trehalose, pirodavir or deuterium oxide to labile vaccines
stabilized the formulation against high temperature8. An identical
strategy would be useful for insulin and oral antidiabetics Distinctive
symbols have been mandatory for inflammables, poisons and radioactive
substances. It would be desirable to insist for distinctive marks on
vials or tablets to indicate storage requirements about temperature and
humidity. Furthermore, simple tests that do not require costly equipment
or trained personnel would be needed to quantify active ingredient of
insulin, suphlonylurea or biguanid in physicians' premises itself.
High and low ambient temperatures modify the assay data on blood glucose.
A glucose load in a tolerance test is associated with different mean
adjusted glucose concentration at a high or low ambient temperature. A 75g
load of glucose in 1030 pregnant women led to 0.20 mmol/L (3.6 mgm %)
higher concentration at 25-31oC than at 20-24oC. The readings at 5-14oC
were 1.03 mmol/ L (18.6 mgm%) lower than at 25-31oC9. Temperature,
humidity, light and altitude 10 also affect the performance of blood
glucose monitors frequently used to quantify glucose in home rather than
hospitals11.
Future effect of global climate warming and the El Niño effect on blood
glucose assay would be minimized after a comprehensive evaluation on the
inimical effects of temperature, humidity, sunlight and altitude on
different parameters. The conventional assays performed in laboratories
and in home with portable glucose meters10 should be meticulously
evaluated to ensure the data on glucose estimates samples were accurate
and precise. An well-integrated approach to ensure availability of potent
therapeutic agents as well as sensitive and specific test for glucose
level would indeed ensure that the harmful effects of climate change would
be countered effectively. Vast magnitude of diabetics all over the globe
need not suffer due to cryptic effects of environment on potency of anti-
diabetic therapeutics r efficacy of glucose quantification technology
available locally.
Subhash C Arya
Centre for Logistical Research and Innovation
M-122 (of part 2), Greater Kailash-II
New Delhi- 110048, India
REFERENCES
1. Physicians' Desk Reference. 53rd edition. Medical Economics
Company. Montvale, 1999
2. United States Environmental Protection Agency. Global warming.
Vice President Gore announces new data showing that July 1998 was the
hottest month on record. August 10, 1998
3. Heat-related mortality- Chicago, July 1998. MMWR 1995; 44: 577-579
4. Kumar S. India's heat wave and rains result in massive death toll.
Lancet 1998;351: 1869
5. Horton R. Croatia and Bosnia: the imprints of War-II.
Consequences. Lancet 1999; 1999;353:771
6. Miller NC, Harris MF. Are childhood immunization programmes in
Australia at risk? Bull Wld Hlth Org 1994; 72:401-408
7. Shakoor O, Taylor RB, Behrens RH. Assessment of the incidence of
substandard drugs in developing countries. Trop Med Int Hlth 1997;2:839-
845
8. In Brown F, editor. New approaches to stabilisation of vaccine
potency. Basel, Karger, 1996
9. Schmidt MI, Matos, Branchtein L, et al. Variation in glucose
tolerance with ambient temperature. Lancet 1994;344:1054-1055
10. Urdang M, Ansede-Luna G, Muller B, et al. An independent pilot
study into the accuracy and reliability of home glucose monitors. Lancet
1999;353:165-166
11. Nichols JH. Laboratory and bedside evaluation of portable glucose
meters: the Author's reply. Am J Clin Path 1995;104:483
Competing interests: No competing interests
There is widespread agreement that for adults a body mass index (BMI)
of 25 kg/m2 constitutes overweight and 30 kg/m2 obesity, but there are no
agreed definitions for children. Cole et al [1] propose using BMI centile
curves and the LMS method to derive childhood standards. First, the z-
scores at age 18 years corresponding to 25 kg/m2 and 30 kg/m2 were
calculated. Next, the BMI values corresponding to these z-scores were
found for children aged 2 to 18 years. The authors thus assume that the
incidence of overweight/obesity remains constant throughout childhood.
The prevalence of overweight increases with age and, using the 1990
British reference data [2] and a definition of 25 kg/m2, is approximately
10-12% at aged 18 years but increases to 20-25% at aged 23 years. However,
the critical period for excessive weight gain is considered to be late
adolescent/early adulthood [3]. Therefore, although 10% of 18 year olds
may well be overweight, it is unlikely that a similar percentage of five-
year-olds will be.
There are difficulties associated with the interpretation of BMI in
childhood, which is dependent on not only on height but also on gender and
pubertal status [4]. Moreover, a recent report comparing BMI cut off
values with percentage body fat in prepubertal children found that
although high cut off points had high specificity the sensitivity was poor
and gender dependent [5].
Body mass index charts, standardised at an agreed level, are
undoubtedly useful for monitoring trends in fatness [6]. It is unlikely,
however, that BMI in itself can provide a standard definition for
overweight and obesity in children that would be useful in clinical
practice.
Yours sincerely
Jean Mulligan
Data Manager
Wessex Growth Study,
Southampton
References
1. Cole TJ, Bellizzi MC, Flegel KM, Dietz WH. Establishing a standard
definition for child overweight and obesity worldwide: international
survey. Br Med J 2000; 320: 1240-1243.
2. Cole TJ, Freeman JV, Preece MA. Body mass index reference curves for
the UK, 1990. Arch Dis Child 1995; 73: 25-29.
3. Power C, Lake JK, Cole TJ. Measurement and long-term health risks of
child and adolescent fatness. Int J Obesity 1997; 21: 507-526.
4. Bini V, Celi F, Berioli MG, Bacosi ML, Stella P, Giglio P, Tosti L,
Falorni A. Body mass index in children and adolescents according to age
and pubertal stage. Eur J Clin Nutr 2000; 54(3): 214-218.
5. Reilly JJ, Savage SA, Ruxton CH, Kirk TR. Assessment of obesity in a
community sample of prepubertal children. Int J Obes 1999; 23(2): 217-219.
6. Voss LD, Mulligan J. Child obesity and body mass index. Lancet 1999;
353: 2070.
Competing interests: No competing interests
EDITOR - Cole TJ et al. proposed a set of sex- and age-specific body mass index (BMI) cut-points as definitions for overweight and obesity status in children, corresponding to an adult BMI of 25 kg/m2and 30 kg/m2 respectively.1 These tables are very useful to clinicians and researchers, as they are based on large, representative, international samples. However, for clinical and epidemiological research, tables may be impractical. We developed a set of commands, which can be used through the Stata Statistical Software (College Station, TX) in order to apply these definitions to a research setting. This set of commands (do-file) can be downloaded by researchers, free of charge on the following web-site:
http://stokes.chop.edu/web/stettler
1. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000; 320: 1240-3.
Nicolas Stettler, Nutrition Fellow
Division of Gastroenterology and Nutrition
The Children's Hospital of Philadelphia
34th Street and Civic Center Boulevard
Philadelphia, PA 19104-4399
USA
Competing interests: No competing interests
Underweight in children – how show we define fine it?
Editor - Cole et al (the International Obesity Task Force (IOFT))
have suggested a new definition of overweight and obesity in children.[1]
The authors argue that the new definition is less arbitrary and more
international than others, and should encourage direct comparison of
trends in child obesity worldwide.
Unfortunately, the authors did not provide definition for
underweight, which is still very important public health problem
especially in many low income countries.[2] As the IOTF definition is more
international and encouraging researchers like me to adopt these new
categories, it will be very useful if they could provide additional
definition for underweight, which might help in assessing and addressing
the underweight problem as well as overweight and obesity problem. This
will also help researchers to be more consistent rather than using this
new definition for overweight and obesity, and the old definition for
underweight.[3]
References
1. Cole TJ, Bellizi MC, Flegal KM & Dietz WH (2000): Establishing
a standard definition for child overweight and obesity worldwide:
international survey. BMJ. 320, 1240–1243.
3. Svedberg P. Declining child malnutrition: a reassessment. Int J
Epidemiol. 2006;35(5):1336-46.
2. de Assis MA, Rolland-Cachera MF, Grosseman S, de Vasconcelos FA,
Luna ME, Calvo MC, Barros MV, Pires MM, Bellisle F. Obesity, overweight
and thinness in schoolchildren of the city of Florianopolis, Southern
Brazil. Eur J Clin Nutr. 2005;59(9):1015-21.
Competing interests:
None declared
Competing interests: No competing interests