Obesity, energy intake and physical activity in rural and urban New Zealand children.

Introduction: Concerns have been raised about childhood obesity and its long-term impact on the health of children. The objective of this study was to investigate rural-urban differences in body composition, energy intake, physical activity and screen time in New Zealand children.

Methods: This study reports on data collected in a large national cross-sectional population survey of 5-15 year-old New Zealanders (the 2002 National Children's Nutrition Survey, CNS02). Schools were randomly selected to participate, as were pupils from the selected schools. Measurements of body composition were taken at school. Energy intake, physical activity and screen time information were taken from interviews and questionnaires undertaken by the child and parent/guardian. Means and standard deviations were calculated in the Statistical Analysis System (SAS Inst; Cary, NC, USA). Differences between groups were analysed using Proc Mixed after adjusting for socio-economic status and ethnicity. Data indicating differences between groups were presented as least square means +/- 95% confidence limits (CL); unless otherwise stated, and the alpha was set at p< 0.05.

Results: Rural children had a significantly lower BMI, smaller waist circumferences and thinner skinfold measurements than urban children. The differences in skinfold thicknesses remained after controlling for ethnicity and socioeconomic status. Furthermore, urban boys were 1.3 times more likely to be overweight or obese than rural boys (95% confidence limits 1.1-1.6, p <0.01) and urban girls were 1.4 times more likely to be overweight or obese than rural girls (95% CL 1.2-1.7, p <0.01).There was no significant difference in the energy intake per day of rural and urban children. Similarly, there was no significant difference in the frequency of bouts of physical activity undertaken by rural and urban children.

Conclusion: Differences were found in body composition with rural children being leaner than urban children. This finding is different from other Western countries and may be due to differences in the physical and social environment in New Zealand. More research is required to understand these potential environmental rural-urban differences.