- OBJECTIVES: The objectives of this study are to: i) examine differences in body mass index (BMI) and prevalence of overweight/obesity between immigrant versus non-immigrant youth aged 12-19 years, and ii) identify the extent to which lifestyle and socio-demographic factors account for between-group differences. METHODS: Data for analyses come from combining repeated, cross-sectional surveys of the Canadian Community Health Survey (CCHS) conducted between 2000 and 2008. The sample for analyses included 63,509 youth aged 12 to 19 years (mean 15.2, SD 2.3 years) with self-reported weight and height. Immigrant youth composed 6.4% of this sample. Multilevel linear and logistic regression analyses were used to address the study objectives. RESULTS: Approximately 22% of non-immigrant youth were overweight/obese, compared to 18% of immigrant youth (p<0.001). Immigrant youth had a lower zBMI by 0.44 compared to non-immigrant youth (p<0.001) and zBMI increased by 0.02 for every year an immigrant-respondent resided in Canada. Measures of lifestyle and socio-demographic factors did not account for differences in body composition between immigrant and non-immigrant youth. CONCLUSION: Even after adjusting for lifestyle and socio-demographic factors, immigrant youth have a lower level of overweight/obesity and a lower zBMI, compared to non-immigrant youth. Further, for immigrant youth zBMI increases with time spent in Canada, which highlights an opportunity for primary preventative strategies for obesity aimed at newcomers to Canada.