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.
Preliminary findings of the effect of a 3-year after-school physical activity intervention on fitness and body fat: the Medical College of Georgia Fitkid Project.
To evaluate the effect of a 3-year after-school physical activity (PA) intervention on aerobic fitness and percent body fat (%BF).
                In total, 18 schools were randomized into intervention or control arms. Measurements were made at the beginning and end of the third, fourth and fifth grades. Fitness was measured with heart rate response to a bench-stepping task.%BF and bone density were measured with dual-energy x-ray absorptiometry. The intervention included 40 min of academic enrichment activities, during which healthy snacks were provided, and 80 min of moderate-to-vigorous PA (MVPA).
                Data analyses were performed on 206 youths who remained in the same schools for the 3-year period, who were measured at all six time points and, for the intervention group, who attended at least 40% of the sessions in each of the 3 years. The group by time interactions were significant for fitness (p < 0.01) and %BF (p < 0.05). Children in intervention schools improved in fitness and %BF during the school years and returned to levels similar to those in control schools during the summers. Over the six measurement points, the intervention group increased more than the control group in bone density (p < 0.01), fat-free soft tissue (p < 0.01), weight (p < 0.01), height (p < 0.01), and body mass index (p < 0.05).
                An after-school program focusing on MVPA had a beneficial effect on fitness and body composition. During the summers, the beneficial effect of the previous year's participation on fitness and %BF was lost. This highlights the importance of year-round programs to promote healthy growth in youths.