Obesity levels in Canada continue to rise
national surveys on obesity levels, conducted between 1985 and
2003, revealing specific trends in the increase in each class of
obesity over the past few decades.
The findings, published in today's issue of the medical journal CMAJ, are not unexpected but continue to put mounting pressure on the food industry, which is held partly responsible for the mounting 'obesity epidemic.'
Peter Katzmarzyk and Caitlin Mason from Queen's University in Kingston, Ontario, found an increase in all levels of obesity, but point out that the number of people suffering from the most extreme form of the disease, class III obesity, increased by 225 percent between 1990 and 2003.
This trend is similar to one reported in a US study in 2002, which revealed a 175 percent increase in class III obesity between 19990 and 2000, but the prevalence of this level of obesity still remains lower in Canada than in the US, said the researchers.
Using 2003 updated guidelines for body weight classification from Health Canada, Katzmarzyk and Mason revealed that general obesity prevalence, measured by a body mass index (BMI) of over 30, more than doubled in the time period, from 6.1 percent to 15.7 percent.
The number of Canadians with class I obesity, measured by a BMI of 30-35, also increased significantly, from 5.1 percent to 11.5 percent. Class II obesity, or a BMI of 35-40 increased from 0.8 percent to 3 percent.
And Canadians classified as 'overweight' have also increased, from 27.8 percent of the population to almost 34 percent.
Indeed, the researchers point out that because their findings were drawn from population surveys, "our estimates are likely to be conservative, since people tend to underestimate their own weight."
And this is confirmed through a comparison of their findings to data published by the 2004 Canadian Community Health Survey, which reveal that the prevalences of directly measured class II and III obesity were 5.1 and 2.7 percent respectively. Results from the population surveys place these figures at 3 and 1.3 percent.
"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," conclude the researchers.