System dynamics modeling of childhood obesity

Summary form only given. Effective strategies for prevention of obesity, particularly in youths, have been elusive since the recognition of obesity as a major public health issue two decades ago. In general, obesity is a result of chronic, quantitative imbalance between energy intake and energy expenditure, which is influenced by a combination of genetic, environmental, psychological and social factors. Therefore, a systems perspective is needed to examine effective obesity prevention strategies. In this study, a systems dynamics model was developed using the data from the Girls health Enrichment Multi-site Studies (GEMS). GEMS tested the efficacy of a 2-year family-based intervention to reduce excessive increase in body mass index (BMI) in 8-10 year old African- American girls. First, an optimum model was built by systematically adding variables to fit the observed data by regression analysis for 50 randomly selected individuals from the cohort. The final model included nutrition, physical activity, and several environmental factors. Next, the model was used to compare two intervention strategies used in the GEMS study. Consistent with previous reports, we found that the two strategies did not affect the BMI increases observed in this cohort. Interestingly however, the model predicted that a 10 min increase in exercise would decrease BMI in the group receiving behavioral counseling. Our work suggests that system dynamics modeling may be useful for testing potential intervention strategies in complex disorders such as obesity.