Obesity rates in Canada have tripled between 1985 and 2011, according to a study from Memorial University in St. John's.

Dr. L.K. Twells analyzed national and provincial data from a number of Canadian health surveys conducted in that time period. His findings, published by the Canadian Medical Association Journal (CMAJ), project that about 21 per cent of Canadian adults will be obese by 2019.

More alarming is the assertion by Twells and his team that health surveys collect information on heights and weights that are reported by individuals. Many people tend to under report and therefore, predictions of Canadians' body mass index (BMI) are likely an underestimation.

Obesity, defined as a BMI of 30 or higher is associated with health risks such as diabetes, high blood pressure and cancer and associated with an annual cost in Canada between $4.6 and $7.1 billion.

Normal weight is classified as a BMI 18.5 to 24.9 while overweight as BMI 25 to 29.9.

Newfoundland and Labrador and New Brunswick had the highest rates of obesity, while rates were lower in western provinces.

Researchers say they are especially concerned about the massive increase in the extreme ends of the obesity spectrum – class 2 and class 3.

In terms of obesity:

- Obesity class 1 is BMI 30 to 34.9.

- Obesity class 2 is BMI 35 to 39.9.

- Obesity class 3 is BMI 40 or over.

According to the findings:

- Obesity rates surged 200 per cent between 1985 and 2011 (from six per cent to 18 per cent).

- For the obesity class 3, New Brunswick reported the highest rate (2.8 per cent) while B.C. and Quebec had the lowest at 1.2 per cent.

- There was a 350 per cent increase in obesity class 2 and a 433 per cent increase in obesity class 3 overall.

- All the provinces had increases in obesity classes 1 and 2.

"These results raise concern at a policy level, because people in these obesity classes are at a much higher risk of developing complex care needs," said the study's authors.

In conclusion, the study points to the various national, provincial and local programs aimed at encouraging healthier lifestyles and weight management, but say that "it's difficult to know which strategies are effective."

They encourage an analysis of all the programs across the country and for an "improved understanding of why such substantial interprovincial variations exist" in terms of approaches to the prevention and treatment of obesity.

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