Effect of school-based interventions on body composition of grade-4 children from lower socioeconomic communities in Gqeberha, South Africa

Background: South African children from disadvantaged communities are plagued by a double burden of under- and over-nutrition. The resulting overweight and obesity on one hand, and stunting on the other hand, are risk factors for chronic diseases in adulthood. Objective: To determine the effect of school-based interventions on body composition of grade-4 children from lower socioeconomic communities in the Port Elizabeth region. Methods: A cluster-randomized controlled trial was carried out with children from eight schools. Schools were randomly assigned, either to a 10-week school-based intervention (4 schools) or a control condition (4 schools). The intervention comprised several arms, with each intervention school receiving a different combination of the following measures: physical activity, health and hygiene education, and nutrition education with supplementation. Effects on children's body composition were evaluated using standardized, quality-controlled methods. Height and weight were assessed to calculate body mass index (BMI), and percentage body fat was measured via thickness of skinfold (triceps and subscapular). Results: Overall, 898 children (458 boys and 440 girls) aged 8-11 years participated in the trial. Children's BMI, BMI for age and percentage body fat increased significantly over time. Increases were similar in boys and girls. Body fat remained unchanged in underweight children, whereas increases occurred in normal weight and (particularly) overweight/obese peers. In normal weight children, the physical activity intervention (either alone or combined with health education) mitigated increments in body fat levels. A similar pattern was observed in overweight/obese children, but only in the physical activity intervention alone. Conclusion: Our study shows that normal weight children are at risk of becoming overweight and children who are already overweight/obese are at even greater risk. The physical activity intervention (alone or in combination with health education) can mitigate increases in body fat in normal weight children as well as in overweight/obese children. Our findings reveal that school-based physical activity, nutrition, and health and hygiene interventions can have beneficial effects on children's body composition. Further analyses are needed to examine how (school-based) physical activity interventions should be designed to improve children's health in lower socioeconomic areas.