Correlates of body weight in the 1994 National Population Health Survey

OBJECTIVE: This study examines three specific questions about obesity and overweight, using a nationally representative sample of Canadians. Are sociodemographic and lifestyle behaviors associated with body weight? Is body weight correlated with specific health outcomes? Has the prevalence of obesity in Canada changed since 1978? METHODS: Secondary data analysis of a cross-sectional survey. SAMPLE: This study uses the 1994 National Population Health Survey (NPHS) by Statistics Canada. It is a stratified random sample of 19,600 Canadians across all provinces. RESULTS: The results show that age, gender, education, birth place and region, are significantly associated with obesity. When a lower criterion is used for overweight and obesity (body mass index, BMI ≤ 25), dummy variables for marital status and occupation are also significant. Second, obesity is associated with poorer self-rated health, high blood pressure, heart disease, diabetes, arthritis, respiratory and stomach problems. For those respondents who have a BMI score of 25 or greater, there is also an association with stroke. Finally, it is unclear whether the prevalence of obesity has changed. However, there appears to be a systematic difference between studies using actual height and weight measurements (anthropometric) vs self-reported measurements. CONCLUSIONS: Weight can be considered a modifiable risk factor and reductions in the prevalence of obesity should reduce the risk of specific chronic conditions. Provincial variations in the prevalence of obesity (BMI ≤ 27) and overweight and obesity (BMI ≤ 25) suggest that collapsing provinces into regions may obscure important interprovincial differences in body weight. More research is required to assess whether or not obesity is decreasing in Canada. Some of the limitations of self-reported data are discussed