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.
Assessment of an after-school physical activity program to prevent obesity among 9- to 10-year-old children: a cluster randomized trial.
To assess the impact of a physical activity program on obesity in primary school children.
                Cluster-randomized controlled trial with 10 intervention and 10 control schools.
                A total of 1044 children, mean age 9.4 years (s.d.=0.7) at baseline, of the Province of Cuenca, Spain.
                Recreational, non-competitive physical activity program conducted after school hours on school premises. The program consisted of three 90-min sessions per week, for 24 weeks.
                Body mass index (BMI), triceps skin-fold thickness (TST) and percentage body fat. Secondary measures were blood lipids and blood pressure. Measurements were made at the beginning (September 2004) and at the end of the program (June 2005). Since schools rather than children were randomized, mixed regression models were used to adjust for individual-level covariates under cluster randomization.
                There were no differences in BMI between the intervention and control groups. Compared with controls, intervention children showed a decrease in TST in both boys (-1.14 mm; 95% confidence interval (CI) -1.71 to -057; P<0.001) and girls (-1.55 mm; 95% CI -2.38 to -0.73; P<0.001), as well as a reduction in the percentage of body fat in girls (-0.58%; 95% CI -1.04 to -0.11; P=0.02). Furthermore, the intervention boys exhibited a decrease in apolipoprotein (apo) B levels (-4.59; 95% CI -8.81 to -0.37; P=0.03) and an increase in apo A-I levels (13.57; 95% CI 7.95-19.20; P<0.001). Blood lipid results in girls were very similar. No changes in total cholesterol, triglycerides or blood pressure were associated with the intervention in either sex, except for an increase in diastolic blood pressure (1.55 mm Hg; 95% CI 0.19-2.91; P=0.03) in the intervention versus control boys.
                An after-school program of recreational physical activity reduced adiposity, increased apo A-I and decreased apo B in primary school children.