Sedentary behaviour and obesity
by Margot Shields and Mark S. Tremblay
This article examines sedentary behaviours (television viewing, computer use and reading) in relation to obesity among Canadian adults aged 20 to 64 years.
MethodsThe analysis is based on 42,612 respondents from the 2007 Canadian Community Health Survey. Cross-tabulations were used to compare the prevalence of obesity by time engaged in sedentary behaviours. Multiple logistic regression models were used to determine if associations between sedentary behaviours and obesity were independent of the effects of socio-demographic variables, leisure-time physical activity and diet.
ResultsApproximately one-quarter of men (25%) and women (24%) who reported watching television 21 or more hours per week were classified as obese. The prevalence of obesity was substantially lower for those who averaged 5 or fewer hours of television per week (14% of men and 11% of women). When examined in multivariate models controlling for leisure-time physical activity and diet, the associations between time spent watching television and obesity persisted for both sexes. Frequent computer users (11 or more hours per week) of both sexes had increased odds of obesity, compared with those who used computers for 5 or fewer hours per week. Time spent reading was not related to obesity.
body mass index, computer use, diet, health behaviour, leisure-time physical activity, reading, television
Over the past 25 years, the prevalence of obesity in Canada has increased substantially among people of all ages. Understanding the causes of this trend is critical for the establishment of effective population-level interventions. [Full text]Margot.Shields@statcan.gc.ca) is with the Health Information and Research Division and Mark S. Tremblay (613-951-4385; Mark.Tremblay@statcan.gc.ca) is with the Physical Health Measures Division at Statistics Canada, Ottawa, Ontario, K1A 0T6 and the Healthy Active Living and Obesity Research Group at the Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, K1H 8L1.
- Numerous studies have examined associations between sedentary behaviours and obesity among children and adolescents. Results provide evidence of a positive association between television viewing and excess weight, but the effects have generally been small.
- Studies of adults have been relatively rare and have usually been based on small-scale surveys or specific population sub-groups and occupations.
- Among Canadian men and women, the odds of being obese increased as weekly hours of television viewing rose. Furthermore, associations between time spent watching television and obesity were independent of leisure-time physical activity and diet.
- When the effects of age and other potential confounding variables were controlled, a modest association was observed between frequent computer use and obesity among men and women.
- Reading was not associated with obesity for either sex.
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