Obesity: An Overview
Over the last twenty years or so, the increased prevalence of obesity here in Canada as well as in other developed countries around the world has been unprecedented.
Is it any wonder that the World Health Organization has listed obesity among the top ten health concerns and that experts predict that it will soon overtake smoking as our number one preventable cause of death?1
The most recent data from the Canadian Community Health Survey: Nutrition2 indicated that nearly one-quarter (23.1%) of adults 18 and older are obese. Another 36.1% are overweight, which is quite alarming.
Not a simple problem, obesity is a complex chronic disease with a diverse etiology.3 Simply put: an interplay of genetics and environment. Studies with identical twins reared apart suggest that the genetic contribution to body mass index may be considerable.4 A unifying theory hypothesizes the existence of a complex “genotype-by-environment” interaction whereby those with a susceptible genotype may have an increased risk of obesity in a society (i.e., environment) that is conducive to weight gain.5
Satiety is no longer the determining factor in ending a meal – rather the meal ends when there’s nothing left on the plate.6 Healthy young American adults were randomized to four different portions of a pasta dish (500 g, 625 g, 750 g or 1000 g) for lunch once a week for four weeks. Permitted to eat as much as they wanted, they consumed 30% more when served the largest versus the smallest portion (p<0.0001)6 – an unnecessary increase of 160 calories. And the problem is only exacerbated by the fact that, in our society over the last few decades, “cleaning one’s plate” has become a moral imperative.
However, it’s not all simply a question of energy balance. It’s quite clearly also a result of the poor diet choices so many consumers all too often make – foods low in nutrients and high in fat and calories, such as commercial baked goods, snacks, and sugary beverages.
But if you think this is an adult problem, think again. Relative to adults, the upswing in childhood obesity is staggering. Since 1978-1979, the overweight/obesity rate in 2- to 17-year-olds for both sexes increased by about 70%. For children aged 2 to 5 years, the overweight/obesity rate was virtually unchanged.7 However, the overweight/obesity rate of 12- to 17-year-olds has more than doubled, and the obesity rate tripled.7 This is of particular importance as adolescence is the critical period for the development of adult obesity.7 More and more, children are presenting health problems that used to be considered adult concerns. For example, the incidence of type 2 diabetes – which used to be called adult-onset diabetes – is growing exponentially in children.8 The prevalence of overweight children is increasing all over the world but, for some reason, Canada appears to be among the most affected.9
The issue of healthy weight and milk products has sparked a great deal of interest in both the media at large and among health professionals.
The Medical Post
The Role of Milk Products in Attaining a Healthy Weight (PDF format. Adobe Reader required.)The prevalence of obesity in Canada has increased by 70% in adults and a whopping 270% in children. Based on interviews, this informative, thought-provoking article was funded by the Dairy Farmers of Canada to help promote knowledge and understanding of this pervasive issue. Developed by Rogers Healthcare and Financial Services, this article first appeared as an insert in the November 22, 2005 issue of The Medical Post.
Drs. Angelo Tremblay, Mark Tremblay, Stephanie Atkinson, and Ian Janssen were interviewed for this article based on their expertise.
Article reproduced in PDF format with the permission of Rogers Healthcare and Financial Services Group.
To order copies, visit the Request for Material section.
References
- Manson JE and Bassuk SS. 2003. Obesity in the United States. A fresh look at its high toll. JAMA 289:229-230.
- Tjepkema M. 2005. Measured Obesity, Adult obesity in Canada: Measured height and weight from Nutrition: Findings from the Canadian Community Health Survey, Issue no.1, Component of Statistics Canada Catalogue no. 82-620-MWE2005001.
- Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. 1998. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: executive summary. Am J Clin Nutr 68:899-917.
- Stunkard AJ et al. 1990. The body-mass index of twins that have been reared apart. N Eng J Med 322:1483-1487.
- Katzmarzyk PT. 2002. The Canadian obesity epidemic: an historical perspective. Obes Res 10:666-674.
- Rolls BJ et al. 2002. Portion size of food affects energy intake in normal-weight and overweight men and women. Am J Clin Nutr 76:1207-1213.
- Sheilds Margot. 2005. Measured Obesity, Overweight Canadian children and adolescents from Nutrition: Findings from the Canadian Community Health Survey, Issue no. 1, Component of Statistics Canada Catalogue no. 82-620-MWE2005001.
- Vivian EM. 2006. Type 2 diabetes in children and adolescents—the next epidemic? Curr Med Res Opin 22:297-306.
- Janssen I et al. 2005. Comparison of overweight and obesity prevalence in school-aged youth from 34 countries and their relationships with physical activity and dietary patterns. Obes Rev 6:123-132.
Keywords: obesity, health studies
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