Free Summer Programming and Body Mass Index Among Schoolchildren From Low-Income Households

ImportanceChildren experience accelerated gains in body mass index (BMI) during the summer months when school is not in session. Children from low-income households are most susceptible. Accelerated BMI gain in summer may be due to the removal of the health-promoting structure provided by schools. During summer, a common form of health-promoting structure is summer day camps (SDCs). Summer day camps are predominately fee for service, which creates a financial barrier for children from low-income households. One solution to mitigate accelerated BMI gain is providing free access to an existing SDC.ObjectiveTo investigate whether providing free access to an existing community SDC can mitigate accelerated BMI z score (zBMI) gain in elementary school–age children.Design, Setting, and ParticipantsThis randomized clinical trial was conducted during the summers of 2021, 2022, and 2023 in the southeastern United States. Participants were children (kindergarten through fourth grade) from predominantly low-income households who were randomized to attend an SDC operated by a parks and recreation commission or continue summer as usual (control).InterventionFree SDC every weekday (Monday through Friday) for 8 to 10 weeks.Main Outcomes and MeasuresThe primary outcome was between-group differences in change of zBMI measured before school ended (May) and on return to school from summer (late August). Secondary analyses examined the dose response of zBMI change with parent-reported child attendance at SDCs during the summer for all children (intervention and control).ResultsA total of 422 children (mean [SD] age, 8.2 [1.5] years; 202 [48%] female, 220 [52%] male, 292 [69%] at or below 200% federal poverty level, 127 [30%] with food insecurity) were randomized to 1 of 2 conditions: summer as usual (control, n = 199) or free SDC (n = 223). Intent-to-treat analysis indicated mean (SE) change in zBMI at the end of the summer was 0.046 (0.027) for the control and −0.048 (0.025) for the intervention group, representing a significant between-group difference of −0.094 (95% CI, −0.166 to −0.022). Dose-response analyses indicated that every 1 day per week increase in attending an SDC resulted in a −0.034 to −0.018 zBMI reduction, which translates to a gain of 0.046 to 0.080 zBMI for children never attending summer programming vs −0.09 to −0.04 zBMI reduction for children attending summer programming every weekday.Conclusions and RelevanceProviding children free access to existing community summer programming can have a meaningful effect on children’s zBMI gain during the summer. Future studies should replicate these findings across different regions and identify the optimal dose of programming to mitigate unhealthy zBMI gains.Trial RegistrationClinicalTrials.gov Identifier: NCT04072549