Middle school transition and body weight outcomes: Evidence from Arkansas Public Schoolchildren

• We investigate the impacts of middle school transition on BMI of children.
• Instrumental variable estimation is employed to identify causality.
• Middle school transition in grade 6 led to moderate BMI z-score decreases.
• Such impacts were driven by boys and especially non-minority boys.
• Changing levels of physical activities provide the best explanation.

There is evidence that middle school transition adversely affects educational and psychological outcomes of pre-teen children, but little is known about the impacts of middle school transition on other aspects of health. In this article, we estimate the impact of middle school transition on the body mass index (BMI) of public schoolchildren in Arkansas, United States. Using an instrumental variable approach, we find that middle school transition in grade 6 led to a moderate decrease of 0.04 standard deviations in BMI z-scores for all students. Analysis by subsample indicated that this result was driven by boys (0.06–0.07 standard deviations) and especially by non-minority boys (0.09 standard deviations). We speculate that the changing levels of physical activities associated with middle school transition provide the most reasonable explanation for this result.