Effect of an environmental school-based obesity prevention program on changes in body fat and body weight: a randomized trial

Abstract

This study tested the efficacy of two school-based programs for prevention of body weight/fat gain in comparison to a control group, in all participants and in overweight children. The Louisiana (LA) Health study utilized a longitudinal, cluster randomized three-arm controlled design, with 28 months of follow-up. Children (N = 2,060; mean age = 10.5 years, SD = 1.2) from rural communities in grades 4-6 participated in the study. Seventeen school clusters (mean = 123 children/cluster) were randomly assigned to one of three prevention arms: (i) primary prevention (PP), an environmental modification (EM) program, (ii) primary + secondary prevention (PP+SP), the environmental program with an added classroom and internet education component, or (iii) control (C). Primary outcomes were changes in percent body fat and BMI z scores. Secondary outcomes were changes in behaviors related to energy balance. Comparisons of PP, PP+SP, and C on changes in body fat and BMI z scores found no differences. PP and PP+SP study arms were combined to create an EM arm. Relative to C, EM decreased body fat for boys (-1.7 ± 0.38% vs. -0.14 ± 0.69%) and attenuated fat gain for girls (2.9 ± 0.22% vs. 3.93 ± 0.37%), but standardized effect sizes were relatively small (<0.30). In conclusion, this school-based EM programs had modest beneficial effects on changes in percent body fat. Addition of a classroom/internet program to the environmental program did not enhance weight/fat gain prevention, but did impact physical activity and social support in overweight children.

Trial registration: ClinicalTrials.gov NCT00289315.

Figure 1

CONSORT flow chart that illustrates the recruitment, random assignment, and retention of participants in the LA Health study. Recruitment of schools was described in greater detail by Williamson et al. (12) Six school clusters declined to participate in the study. The decisions by the school administrators of these six clusters were unique to each school system, but none refused to participate because the focus of the project was healthy weight, eating, and activity.

Figure 2

Changes in percent body fat over time as a function of intervention arm (Abbreviations: EM arm = Primary Prevention combined with Primary + Secondary Prevention). Panel A depicts changes for boys and panel B depicts changes for girls.

Figure 3

Changes in dietary fat intake over time as a function of intervention arm (Abbreviations: EM arm = Primary Prevention combined with Primary + Secondary Prevention).