CMAJ 2005;173(6):607-13 We measured standing height to the nearest 0.1 cm after students had removed their shoes and body weight to the nearest 0.1 kg on calibrated digital scales. Overweight and obesity were defined using the international body mass index cut-off points established for children and youth. 26 These cut-off points are based on healthrelated adult definitions of overweight (≥ 25 kg/m 2 ) and obesity (≥ 30 kg/m 2 ) but are adjusted to specific age and sex categories for children. 26The CLASS survey included a modified version of Harvard's Youth/Adolescent Food Frequency Questionnaire, 27 which gathers information on both dietary intake and habits pertaining to mealtime behaviours. It also included validated questions on the frequency of physical activities and the number of hours of sedentary activities (watching television, working on a computer, playing video games) taken from the National Longitudinal Survey of Children and Youth (NLSCY).28 Information on sociodemographic factors was taken from a survey completed by parents and included the child's sex, place of birth and residency, as well as the parents' marital status, income level and educational attainment. The children's ages were not included, since the vast majority of grade 5 students were either 10 or 11 years old at the time they completed the CLASS survey.We estimated neighbourhood income by averaging, per school, the postal-code level means of household income (available through the 2001 Canada census) of residential addresses of children attending that school. Finally, we developed and administered a short survey for school principals to collect information on school characteristics, including sales of soft drinks, presence of vending machines, type of food services, frequency of physical education classes and possible financial restraints for recreation and gymnasium equipment.Because our observations of students are nested within those of their schools, we assessed student and school-based factors at distinct levels using multilevel statistical methods. Specifically, student and parental factors were considered as first-level covariates. All school characteristics and neighbourhood income were considered as contextual factors and treated as second-level covariates. We first applied multilevel logistic regression methods to determine to what extent risk factors were associated with overweight or obesity. Second, we grouped each risk factor into 1 of 4 groups -dietary habits, activities, and sociodemographic and school-based factors -and then adjusted for all significant risk factors within each group. These estimates are referred to as theme-adjusted odds ratios. Third, we considered all significant risk factors simultaneously to quantify their independent importance for excess body weight.Because participation rates were slightly lower in residential areas with lower estimates of household income, we calculated re- †Theme-adjusted odds ratios are adjusted for lunch, family supper and supper in front of the television. ‡Fully...

Our finding that school programs are effective in preventing childhood obesity supports the need for broader implementation of successful programs, which will reduce childhood obesity and, in the longer term, comorbid conditions and health care spending.

Objective: Public health policies promote healthy nutrition but evaluations of children's adherence to dietary recommendations and studies of risk factors of poor nutrition are scarce, despite the importance of diet for the temporal increase in the prevalence of childhood obesity. Here we examine dietary intake and risk factors for poor diet quality among children in Nova Scotia to provide direction for health policies and prevention initiatives. Methods: In 2003, we surveyed 5,200 grade five students from 282 public schools in Nova Scotia, as well as their parents. We assessed students' dietary intake (Harvard's Youth Adolescent Food Frequency Questionnaire) and compared this with Canadian food group and nutrient recommendations. We summarized diet quality using the Diet Quality Index International, and used multilevel regression methods to evaluate potential child, parental and school risk factors for poor diet quality. Results: In Nova Scotia, 42.3% of children did not meet recommendations for milk products nor did they meet recommendations for the food groups 'Vegetables and fruit' (49.9%), 'Grain products' (54.4%) and 'Meat and alternatives' (73.7%). Children adequately met nutrient requirements with the exception of calcium and fibre, of which intakes were low, and dietary fat and sodium, of which intakes were high. Skipping meals and purchasing meals at school or fast-food restaurants were statistically significant determinants of poor diet. Parents' assessment of their own eating habits was positively associated with the quality of their children's diets. Interpretation: Dietary intake among children in Nova Scotia is relatively poor. Explicit public health policies and prevention initiatives targeting children, their parents and schools may improve diet quality and prevent obesity. MeSH terms: Nutrition; obesity; child; lifestyle; prevention & control; public health La traduction du résumé se trouve à la fin de l'article.

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