The objectives of this study were to implement, test adherence to and examine the preliminary effectiveness of a summertime weight-gain prevention intervention in youth from a low-income, Rhode Island community. In 2016, 51 children, ages 6–12 years, participated in a daily, summertime intervention, which offered a minimum of two hours of physical activity programming and free lunch through the USDA's Summer Food Service Program (SFSP). Thirty children from the same community with similar SFSP access served as a comparison group. Height and weight were measured before and at the end of summer to assess change in body mass index z-score (BMIz). Diet and physical activity were assessed midsummer. Multivariate mixed models were used to test group differences in change in BMIz over the summer and weight-related behaviors midsummer. Repeated measures ANOVA was used to examine the relationships of intervention participation with change in BMIz and weight-related behaviors in intervention participants. On average, intervention participants attended 65.6% of program sessions. They lost 0.04 BMIz units, while those in the comparison group gained 0.03 BMIz units (p = 0.07). Midsummer, intervention participants spent 4.6% less time sedentary on weekdays as compared to comparison participants (p = 0.03). Among intervention participants, attendance was significantly associated with change in BMIz (p = 0.01), spending 41 more minutes in moderate to vigorous physical activity (MVPA) (p = 0.004) and 8.5% less time sedentary (p < 0.001). Implementing a summertime obesity prevention intervention in a low-income community is feasible. Despite moderate adherence, preliminary findings suggest that participation in the intervention was associated with reductions in BMIz.Clinical trials registrationClinicalTrials.govNCT03118635

Background Children from racial and ethnic minority groups, low-income households, and those with overweight or obesity gain more weight during the summer than the school year. Summer day camps, which offer routine opportunities for physical activity and regular meal and snack times, have potential to mitigate excess weight gain. This randomized controlled trial was done to determine the feasibility and preliminary effectiveness of summer camp in preventing excess summer weight gain among youth from low-income households. Methods Children, ages 6 to 12 years, were randomized to attend 8-weeks of summer day camp (CAMP) or to experience an unstructured summer as usual (SAU) in 2017–2018. Primary feasibility outcomes included retention, engagement and completion of midsummer measures. Secondary outcomes included changes in BMIz, engagement in moderate to vigorous physical activity (MVPA) and sedentary behavior, and diet quality and energy intake from the school year to summer. Multivariable linear mixed models were used to assess group differences. Results Ninety-four participants were randomized to CAMP (n = 46) or SAU (n = 48), of whom 93.0 and 91.6% completed end of school and end of summer assessments, respectively. While CAMP participants attended only 50% of camp days offered, on average, they lost − 0.03 BMIz units while those in SAU gained 0.07 BMIz units over the summer (b = 0.10; p = .02). Group differences in change in energy intake from the school year to summer were borderline significant, as energy intake remained relatively unchanged in CAMP participants but increased among participants in SAU (p = 0.07). Conclusions Randomizing children to attend summer day camp or experience an unstructured summer as usual was effective in this low-income sample. Our findings support the potential for summer camps in mitigating excess summer weight gain. A larger randomized trial is needed explore efficacy, cost-effectiveness and longer-term effects of attending summer camp on weight and weight-related behaviors. Trial registration ClinicalTrials.gov Registration: NCT04085965 (09/2019, retrospective registration).