We found strong evidence to support beneficial effects of child obesity prevention programmes on BMI, particularly for programmes targeted to children aged six to 12 years. However, given the unexplained heterogeneity and the likelihood of small study bias, these findings must be interpreted cautiously. A broad range of programme components were used in these studies and whilst it is not possible to distinguish which of these components contributed most to the beneficial effects observed, our synthesis indicates the following to be promising policies and strategies:
·         school curriculum that includes healthy eating, physical activity and body image
·         increased sessions for physical activity and the development of fundamental movement skills throughout the school week
·         improvements in nutritional quality of the food supply in schools
·         environments and cultural practices that support children eating healthier foods and being active throughout each day
·         support for teachers and other staff to implement health promotion strategies and activities (e.g. professional development, capacity building activities)
·         parent support and home activities that encourage children to be more active, eat more nutritious foods and spend less time in screen based activities
However, study and evaluation designs need to be strengthened, and reporting extended to capture process and implementation factors, outcomes in relation to measures of equity, longer term outcomes, potential harms and costs.
Childhood obesity prevention research must now move towards identifying how effective intervention components can be embedded within health, education and care systems and achieve long term sustainable impacts.
Influence of a health education intervention on physical activity and screen time in primary school children: 'Switch Off--Get Active'.
Low levels of physical activity coupled with high levels of television viewing have been linked with obesity in children. The objective of this study was to assess the efficacy of 'Switch Off-Get Active', a 16-week controlled health education intervention, in increasing physical activity and reducing screen time and BMI in primary school children. A secondary objective was to compare children with high and low screen time. Participants were 312 children aged 10.2+/-0.7 years, attending nine schools in areas of social disadvantage. The 10-lesson, teacher-led intervention, conducted in spring 2003, emphasised self-monitoring, budgeting of time and selective viewing. Differences, adjusted for baseline values by ANCOVA, existed between intervention and control children at follow-up for self-reported physical activity (intervention +0.84 30 min blocks/day, 95%CI 0.11-1.57, p<0.05) and self-efficacy for physical activity (p<0.05) but not self-reported screen time (intervention--0.41 blocks/day, 95%CI--0.93-0.12, p=0.13) or BMI (p=0.63). Cross-sectional comparisons at baseline indicated lower physical activity, self-efficacy for physical activity and aerobic fitness and a higher BMI in children with high screen time. In conclusion, health education interventions can increase physical activity in primary school children but follow-ups of longer duration may be needed to demonstrate intervention effects on BMI.