Obesity in Canada: where and how many?

Context: Obesity rates are rising sharply among all industrialized countries; the situation seems to be worse in English speaking countries. Taking into account genetic predisposition, excess of caloric intake combined with low energy expenditure will usually result in obesity. Objectives: To describe and compare regional obesity rates across Canada and assess the ecological relationship between regional rates of obesity, low level of leisure-time physical activity, and low fruit and vegetable consumption. Design: Cross-sectional population-based analysis from the 2003 Canadian Community Health Survey. Measures and data analyses: Canadian population distributions of body mass index (BMI), leisure-time physical activity and daily fruit and vegetable consumption were obtained from Statistics Canada. All these measures were based on the respondent's self-reported answers to a computer-assisted personal or telephone interview. Obesity rates (BMI >= 30), rates of low level of leisure-time physical activity ( less than 1.5 kcal of energy expenditure per day), and rates of low fruit and vegetable consumption ( less than five times a day) for the 106 Canadian Health regions were mapped to illustrate their geographical distribution. Cartograms were used in addition to traditional mapping to take into account the differences in population density between these small areas. Results: In 2003, 15.2% of Canadian individuals aged 20 years and older were considered obese. The rates of obesity varied substantially between the 106 Canadian health regions: from 6.2% in Vancouver to 47.5% in aboriginal population area. At the health region level, low leisure-time physical activity and low fruit and vegetable consumption are both good predictors of obesity ( odds ratio of 9.2 and positive predictive value of 93% when considered simultaneously). Conclusion: There is a strong gradient in obesity prevalence between Canadian health regions. At the regional level, high rates of low level of physical activity, and high rates of low fruit and vegetable consumption were both found good predictors of high rates of obesity.