Correlates of body mass index among a nationally representative sample of New Zealand children

Objectives. To describe how nutrition behaviours and physical activity are associated with body mass index (BMI) among New Zealand children and to determine if these relationships vary by ethnicity. Methods. Data were collected during the 2002 National Children's Nutrition Survey. 3250 children provided information about their eating and activity behaviours and anthropometric measurements. Results. Approximately 31% of New Zealand children aged 5 to 14 years were overweight/obese, with the highest prevalences of overweight/obesity among Pacific children (62%) and Maori children (41%). Higher prevalences of obesity were also observed among females and children experiencing socioeconomic deprivation. Television use, buying school food from the dairy/takeaway shops, skipping breakfast, consumption of fruit drinks/soft drinks, and low physical activity were associated with BMI in analyses controlling for demographic characteristics among the total population. Buying school food from the dairy/takeaway (p=0.04) and skipping breakfast (p=0.007) retained significance when all nutrition behaviours and physical activity were analysed simultaneously. Significant interactions between ethnicity and bringing school food from home and buying school food from school were observed in relation to BMI. In most cases, the relationships were most significant for Pacific children. Conclusions. Strategies to address childhood obesity among all New Zealand children should primarily include efforts to increase breakfast consumption and decrease food purchases away from home. Given the high rates of obesity between Pacific and Maori children, targeted interventions are warranted and should include strategies to improve the school food environment.