Advertisement
ADVANCED SEARCH

This Article Figures Only Full Text (PDF) Online Table Submit a response View responses Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Katzmarzyk, P. T. Articles by Mason, C. Search for Related Content PubMed PubMed Citation Articles by Katzmarzyk, P. T. Articles by Mason, C. Related Collections Obesity

Prevalence of class I, II and III obesity in Canada

School of Physical and Health Education, Department of Community Health and Epidemiology, Queen's University, Kingston, Ont.

Obesity places a substantial burden on public health in Canada, and people with more extreme levels of obesity are at substantially increased risk of premature death. In 2003, Health Canada issued updated guidelines for body weight classification in adults (available at www.hc-sc.gc.ca/fn-an/nutrition/weights-poids/guide-ld-adult/index_e.html). Within this framework, adults are considered overweight if their body mass index (BMI, kg/m²) is 25 or greater, and obese if their BMI is 30 or greater. Obesity is further separated into 3 classes according to the increased health risks associated with increasing BMI levels: class I (BMI 30– 34.9), class II (BMI 35– 39.9) and class III (BMI 40). The obesity class guides treatment options: therapeutic lifestyle changes (e.g., increases in physical activity and reductions in dietary intake) should be considered for all obese people, whereas the use of more aggressive approaches to weight loss (e.g., pharmacotherapy or bariatric surgery) are generally reserved for people with more extreme obesity (class II or III) and those with additional risk factors.

Although the prevalence of overall obesity is known to have increased in Canada over recent decades,¹ we sought to determine specific trends for each class of obesity, especially the more extreme classes. We examined the results of 7 surveys of nationally representative samples of Canadians conducted from 1985 through 2003. The surveys included the 1985 and 1990 Health Promotion Surveys, the 1994/95, 1996/97 and 1998/99 National Population Health Surveys, and the 2000/01 and 2003 Canadian Community Health Surveys. Based on the participants' reported heights and weights, we calculated their BMIs and classified them as being not overweight, overweight or obese (class I, II or III). We calculated age-adjusted weighted prevalences of overweight and obesity among the participants (available in an online table at www.cmaj.ca/cgi/content/full/174/2/156/DC1).

The prevalences of overweight and all levels of obesity in Canada have increased between 1985 and 2003 (Fig. 1). We found that the prevalence of class III obesity increased from 0.4% to 1.3% between 1990 and 2003, a 225% increase. This trend is similar to that reported in a US study, which reported an increase in prevalence of class III obesity from 0.8% to 2.2% between 1990 and 2000 (a 175% increase).² However, the absolute prevalence of class III obesity in Canada remains lower than that in the United States. There are no comparable data from Europe.

View larger version (52K): [in this window] [in a new window]   Fig. 1: Prevalence of overweight and obesity (classes I–III) in Canada, 1985–2003. Top: Changes in absolute prevalence. Bottom: Changes relative to baseline (1985 = 100%).

Our estimates are likely conservative, since people tend to underestimate their own weight. An important area of future research is to document changes in the prevalence of class II and III obesity using directly measured data. Indeed, data recently released from the 2004 Canadian Community Health Survey indicate that the prevalences of directly measured class II and III obesity were 5.1% and 2.7%, respectively,³ which are higher than our estimates of 3.0% and 1.3%, respectively, calculated from the 2003 survey data. Similar differences between directly measured and self-reported obesity have also been reported in the United States.

The increases in prevalence of overweight and all levels of obesity in Canada between 1985 and 2003 are cause for concern given the markedly increased risk of premature death and of metabolic and musculoskeletal complications arising from morbid obesity.¹ The rapid increase in the prevalences of class II and III obesity will undoubtedly have a significant impact on our health care system.

Footnotes

Acknowledgement: Our work was supported by a New Emerging Team grant from the Canadian Institutes of Health Research and the Heart and Stroke Foundation of Canada.

Competing interests: None declared.

REFERENCES

1. Katzmarzyk PT. The Canadian obesity epidemic, 1985–1998 [editorial]. CMAJ 2002;166(8):1039-40.[Free Full Text]
2. Freedman DS, Khan LK, Serdula MK, et al. Trends and correlates of class 3 obesity in the United States from 1990 through 2000. JAMA 2002;288:1758-61.[Abstract/Free Full Text]
3. Tjepkema M. Measured obesity. Adult obesity in Canada: measured height and weight. In: Nutrition: findings from the Canadian Community Health Survey 2004;issue 1 (cat no 82-620-MWE2005001). Available: www.statcan.ca/english/research/82-620-MIE/2005001/articles/adults/aobesity.htm (accessed 2005 Dec 8).

This article has been cited by other articles:

				R. S. Padwal and A. M. Sharma Treating severe obesity: morbid weights and morbid waits Can. Med. Assoc. J., November 24, 2009; 181(11): 777 - 778. [Full Text] [PDF]

				J. Stritzke, M. R. P. Markus, S. Duderstadt, W. Lieb, A. Luchner, A. Doring, U. Keil, H.-W. Hense, H. Schunkert, and for the MONICA/KORA Investigators The Aging Process of the Heart: Obesity Is the Main Risk Factor for Left Atrial Enlargement During Aging The MONICA/KORA (Monitoring of Trends and Determinations in Cardiovascular Disease/Cooperative Research in the Region of Augsburg) Study. J. Am. Coll. Cardiol., November 17, 2009; 54(21): 1982 - 1989. [Abstract] [Full Text] [PDF]

				E. S. Ford and A. H. Mokdad Epidemiology of Obesity in the Western Hemisphere J. Clin. Endocrinol. Metab., November 1, 2008; 93(11_Supplement_1): s1 - s8. [Abstract] [Full Text] [PDF]

				K. Tu MD MSc, Z. Chen MD MSc, L. L. Lipscombe MD MSc, and for the Canadian Hypertension Education Program Ou Prevalence and incidence of hypertension from 1995 to 2005: a population-based study Can. Med. Assoc. J., May 20, 2008; 178(11): 1429 - 1435. [Abstract] [Full Text] [PDF]

				E. D. Abel, S. E. Litwin, and G. Sweeney Cardiac Remodeling in Obesity Physiol Rev, April 1, 2008; 88(2): 389 - 419. [Abstract] [Full Text] [PDF]

				M. Poulain, M. Doucet, V. Drapeau, G. Fournier, A. Tremblay, P. Poirier, and F. Maltais Metabolic and inflammatory profile in obese patients with chronic obstructive pulmonary disease Chronic Respiratory Disease, February 1, 2008; 5(1): 35 - 41. [Abstract] [PDF]

eLetters:

This Article Figures Only Full Text (PDF) Online Table Submit a response View responses Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Katzmarzyk, P. T. Articles by Mason, C. Search for Related Content PubMed PubMed Citation Articles by Katzmarzyk, P. T. Articles by Mason, C. Related Collections Obesity

HOME	CURRENT ISSUE	PAST ISSUES	COLLECTIONS	HELP	SEARCH
Copyright 1995-2006, Canadian Medical Association. All rights reserved. ISSN 1488-2329 (e) 0820-3946 (p) All editorial matter in CMAJ represents the opinions of the authors and not necessarily those of the Canadian Medical Association.