Purpose: To examine secular trends in obesity and overweight among Canadian adults between 1970 and 1992. The impact of education level and smoking on weight trends is explored.
Data: Adults aged 20-69 participating in three national health surveys which obtained measured height and weight: the Nutrition Canada Survey conducted between 1970 and 1972 (analysis sample n=5963); the Canada Health Survey of 1978-1979 (analysis sample n=3622); and the Canadian Heart Health Surveys conducted between 1986 and 1992 (analysis sample n=17 699).
Methods: Comparison of percentage overweight (age-standardized body mass index (BMI) 25.0-29.9) and obese (age-standardized BMI > or = 30.0) by sex, education level and smoking status across the three surveys.
Results: Among men, the proportion overweight and obese increased steadily from 1970-1972 to 1986-1992. Among women, there was a substantial increase in the proportion overweight and obese between 1970-1972 and 1978-1979, then an increase in proportion obese, but not overweight, between 1978-1979 and 1986-1992. Although the prevalence of obesity increased in all education levels, the sub-groups with the greatest relative increase are men in the primary education category, and women in the secondary and post-secondary between 1970-1972 and 1986-1992. An increase in the prevalence of obesity was greatest among current smokers and, to a lesser extent, among former smokers.
Conclusion: While excess weight has become an increasing public health problem among Canadian adults, the rate of increase in prevalence of obesity since 1970 varied with sex, education level and smoking status. There is a need for new data on measured heights and weights of Canadian adults and children and youth to update trends.