Impact of a year‐round school calendar on children's BMI and fitness: Final outcomes from a natural experiment

Abstract

Background: Structure may mitigate children's accelerated summer BMI gain and cardiorespiratory-fitness (CRF) loss.Objectives: Examine BMI and CRF change during school and summer for year-round and traditional calendar school children.Methods: Three schools (N = 2279, 1 year-round) participated in this natural experiment. Children's BMI z-score (zBMI) and CRF (PACER laps) were measured from 2017 to 2019 each May/August. Mixed effects regression estimated monthly zBMI and CRF change during school/summer. Secondary analyses examined differences by weight status and race. Spline regression models estimated zBMI and CRF growth from kindergarten-sixth grade.Results: Compared to traditional school, children attending a year-round school gained more zBMI (difference = 0.015; 95CI = 0.002, 0.028) during school, and less zBMI (difference = −0.029; 95CI = −0.041, −0.018), and more CRF (difference = 0.834; 95CI = 0.575, 1.093) monthly during summer. Differences by weight status and race were observed during summer and school. Growth models demonstrated that the magnitude of overall zBMI and CRF change from kindergarten-sixth grade was similar for year-round or traditional school children.Conclusions: Contrary to traditional school children zBMI increased during the traditional 9-month school calendar and zBMI decreased during the traditional summer vacation for year-round school children. Structured summer programming may mitigate accelerated summer BMI gain and CRF loss especially for overweight or obese, and/or Black children.

Children’s Health, Wellbeing and Academic Outcomes over the Summer Holidays: A Scoping Review

“…Of the studies measuring adiposity, 84% (21/25) found an increase over the summer [ 9 , 31 , 32 , 35 , 37 , 43 , 45 , 47 , 49 , 52 , 54 , 61 , 64 , 73 , 74 , 75 , 76 , 85 , 86 , 93 , 96 , 99 , 100 , 101 ]. Two studies (8%, 2/25) displayed mixed results [ 26 , 95 ] and two more showed a decrease in adiposity over the summer [ 39 , 104 ] ( Figure 3 ).…”

Depressive Symptoms and Their Longitudinal Impact on Physical Activity and Sedentary Behaviors Among Mexican-Heritage Youth

“…Nevertheless, our study has several strengths. We employed a longitudinal, family-based design that allowed for PA assessments during both out-of-school (eg, summer season) and in-school (eg, fall season) time points, which is an important consideration for the youth given the educational and seasonal variations in PA over time 76,77. Our ethnically homogenous sample allowed us to identify patterns in depression and PA that can be used for culturally appropriate intervention development among Mexican-heritage families.…”

“…We employed a longitudinal, family-based design that allowed for PA assessments during both out-of-school (eg, summer season) and in-school (eg, fall season) time points, which is an important consideration for the youth given the educational and seasonal variations in PA over time. 76,77 Our ethnically homogenous sample allowed us to identify patterns in depression and PA that can be used for culturally appropriate intervention development among Mexican-heritage families. Hispanic/Latinx populations, the majority of whom are of Mexican heritage, 78 are one of the largest and fastest growing race/ethnic minority groups in the US and make up almost 1 in 5 people in the US.…”

Seasonal variability in body mass index change among children enrolled in the Pediatric Obesity Weight Evaluation Registry: A step in the right direction

“…Recent research has highlighted that body mass index (BMI) gain in children is not consistent throughout the calendar year; children seem to disproportionately experience excess BMI gain over the summer months compared with other periods of the year (e.g., school months) 4–8 . Several studies have provided longitudinal evidence of summer accelerated BMI changes demonstrating a consistent pattern of findings 9–21 . Accelerated BMI gain during the summer has been found to be amplified for children who already have obesity, 9–14,16,22,23 children from lower socioeconomic backgrounds, 9,15,19 and Hispanic and Black children 12–15,21 .…”

“…[4][5][6][7][8] Several studies have provided longitudinal evidence of summer accelerated BMI changes demonstrating a consistent pattern of findings. [9][10][11][12][13][14][15][16][17][18][19][20][21] Accelerated BMI gain during the summer has been found to be amplified for children who already have obesity, [9][10][11][12][13][14]16,22,23 children from lower socioeconomic backgrounds, 9,15,19 and Hispanic and Black children. [12][13][14][15]21 Over several summers, accelerated BMI gain has the potential to create a compounding effect, resulting in substantial disparities between groups akin to the 'summer setback' gap in academic achievement between low and middle/upper socioeconomic families.…”