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OBJECTIVE: To assess changes in the prevalence of overweight and obesity among Canadian children and adults between 1981 and 1996 using recent recommendations for the classification of overweight and obesity. DESIGN: Epidemiological study comparing the prevalence of overweight and obesity from the 1981 Canada Fitness Survey (CFS) to the 1996 National Longitudinal Survey of Children and Youth (NLSCY) and the 1996 National Population Health Survey (NPHS). SUBJECTS: Adults 20-64 y of age and children 7-13 y of age from the CFS, NLSCY and NPHS. MEASUREMENTS: BMI was calculated from directly measured or self-reported body mass and height. For adults 20-64 y of age, overweight and obesity were defined as BMI 25 kg=m 2 and BMI 30 kg=m 2 , respectively. Age-and sex-specific cut-off points for children that correspond to the adulthood categories were used to define overweight and obesity for children 7-13 y of age. RESULTS: The prevalence of overweight increased from 48 to 57% among men and from 30 to 35% among women, while the prevalence of obesity increased from 9 to 14% in men and from 8 to 12% in women. The corresponding increases were from 11 to 33% in boys and from 13 to 27% in girls for overweight and from 2 to 10% in boys and from 2 to 9% in girls for obesity. CONCLUSION:The results indicate dramatic increases in the prevalence of both overweight and obesity in Canada over the last 15 y, and the problem is particularly pronounced among children.

OBJECTIVE: This study examined the relation among children's physical activity, sedentary behaviours, and body mass index (BMI), while controlling for sex, family structure, and socioeconomic status. DESIGN: Epidemiological study examining the relations among physical activity participation, sedentary behaviour (video game use and television (TV)/video watching), and BMI on a nationally representative sample of Canadian children. SUBJECTS: A representative sample of Canadian children aged 7-11 (N ¼ 7216) from the 1994 National Longitudinal Survey of Children and Youth was used in the analysis. MEASUREMENTS: Physical activity and sport participation, sedentary behaviour (video game use and TV/video watching), and BMI measured by parental report. RESULTS: Both organized and unorganized sport and physical activity are negatively associated with being overweight (10-24% reduced risk) or obese (23-43% reduced risk), while TV watching and video game use are risk factors for being overweight (17-44% increased risk) or obese (10-61% increased risk). Physical activity and sedentary behaviour partially account for the association of high socioeconomic status and two-parent family structure with the likelihood of being overweight or obese. CONCLUSION: This study provides evidence supporting the link between physical inactivity and obesity of Canadian children.

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This study examined the relationships between children's reported levels of physical activity, body-mass index, self-esteem, and reading and mathematics scores, while controlling for sex, family structure, and socioeconomic status.The data were collected from the full population of Grade 6 students (N = 6,923) in New Brunswick (NB), Canada in 1996, as part of the Elementary School Climate Study, and the NB Department of Education's Grade 6 Assessment. Physical activity had a negative relationship with body-mass index. Physical activity had a positive relationship with self-esteem, and a trivial negative relationship with academic achievement. The analysis revealed that both females and males who were more physically active had considerably higher levels of self-esteem. The study suggests that the relationship between physical activity and academic achievement is weak. For some children, physical activity may be indirectly related to enhanced academic performance by improving physical health and self-esteem.