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. 2001 Oct 27;323(7319):999.

Single definition of overweight and obesity should be used

Susan A Jebb 1,2, Andrew M Prentice 1,2
PMCID: PMC1121519  PMID: 11679395

Editor—In May 2000 the BMJ published details of a new reference standard for childhood obesity developed by the International Obesity Task Force.1 The task force's standards take a logical and pragmatic approach to the problem of defining the cut-off points of body mass index indicating overweight and obesity in children.

In adults these cut-off points are based on the morbidity and mortality associated with excess weight. In the absence of such data in children the task force defined the cut-off points for young people by back-extrapolating from the centile of body mass index corresponding to values of >25 kg/m2 (overweight) and 30 kg/m2 (obese) at age 18. Subsequent papers in the BMJ and elsewhere, however, have not all applied this definition, instead choosing more liberal cut-off points, usually the 85th and 95th centiles of national standards for overweight and obesity respectively. This practice has several flaws.

Firstly, different values are obtained according to which centile standards are used, which makes international comparisons impossible.

Secondly, the true nature of secular trends are obscured if updated standards are used; these standards are themselves affected by the developing epidemic of obesity (leading ultimately to the self fulfilling prophecy that there will always be 15% overweight and 5% obesity if these cut-off points are applied to contemporary standards).

Thirdly, the choice of 85th and 95th centiles effectively inflates the apparent number of overweight and obese children.2,3 This has led to confusion over the prevalence of obesity in young people.

The upward trend in childhood obesity is clearly of major concern even without any artificial inflation of the statistics. The prevalence of obesity has roughly trebled in 20 years4—a similar increase to that seen in adults. This secular trend should be the basis for strategies to tackle excess weight gain in young people. Exaggerating the absolute prevalence of obesity is ultimately unhelpful since it leads to confusing discrepancies in the transition from children to adults. For example, using the 95th centile of United Kingdom standards indicates that about 14% of 16 year olds were obese in the national diet and nutrition survey of young people 19975; when the adult cut-off point of body mass index 30 kg/m2 is used, however, only 5.8% are defined as obese.

Public health policy will best be served by a single definition of overweight and obesity in children and young people, which is consistently applied. We urge health professionals, scientists, and editors to adopt the International Obesity Task Force's proposed reference standard for obesity in children.

References

  • 1.Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ. 2000;320:1240–1243. doi: 10.1136/bmj.320.7244.1240. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Rudolf MCJ, Sahota P, Barth JH, Walker J. Increasing prevalence of obesity in primary school children: cohort study. BMJ. 2001;322:1094–1095. doi: 10.1136/bmj.322.7294.1094. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Bundred P, Kitchiner D, Buchan I. Prevalence of overweight and obese children between 1989 and 1998: population based series of cross sectional studies. BMJ. 2001;322:1–4. doi: 10.1136/bmj.322.7282.326. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Chinn S, Rona RJ. Prevalence and trends in overweight and obesity in three cross sectional studies of British children, 1974-94. BMJ. 2001;322:24–26. doi: 10.1136/bmj.322.7277.24. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Finch S, Doyle W, Lowe C, Bates CJ, Prentice A, Smithers G, et al. National diet and nutrition survey: people aged 65 years and over. 1. Report of the diet and nutrition survey. London: Stationery Office; 1998. [Google Scholar]

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