The Role of Early and Later Response on Overall Outcomes in School-Based Obesity Intervention

Objective: Early response to obesity intervention consistently predicts long-term BMI reductions. However, little is known about how changes in weight at other times in an intervention may impact long-term outcomes. This study examined the relationship between weight-related changes that occurred early and later during an intervention and the association between these changes with overall outcomes. Methods: A secondary analysis of a school-based obesity intervention with replicated efficacy among Hispanic middle school students was conducted (n = 174). Linear regression models were developed in which first and second semester changes in BMI represented as a percentage of the 95th BMI percentile (%BMIp95) were separately used to predict overall %BMIp95 outcomes. First semester changes in %BMIp95 were used to predict subsequent %BMIp95 change (i.e., second semester). Results: Changes in %BMIp95 during both the first and second semesters were independently associated with overall changes from baseline (e.g., at 24 months: first semester, β = 0.59, P < 0.01; second semester, β = 1.02, P < 0.001). First semester %BMIp95 change was not associated with second semester change (β = −0.07, P = 0.32). Conclusions: Change at any point during the intervention was predictive of overall weight outcomes. Additional research is needed to understand patterns of weight changes throughout interventions to better understand long-term outcomes.