Are closed campus policies associated with adolescent eating behaviours?

INTRODUCTION: The effectiveness of school nutrition regulations may be undermined by food environments surrounding schools. Given challenges in regulating external retail, some have recommended policies that ensure students are unable to leave school property during the day (closed campus policies; CCP). We aimed to examine whether CCP are associated with student eating behaviours.
METHODS: We used student and school-administrator survey data from the 60 610 Grades 9 to 12 students and 134 Canadian secondary schools that participated in Year 7 (2018/19) of the COMPASS study. Multiple ordinal regression models tested school CCP as a predictor of weekday dietary behaviours (0-5 days), controlling for student-level (grade, sex, spending money, ethnicity) and school-level (urbanicity, province, area median household income, vending machines) covariates.
RESULTS: CCP were reported by 16 schools. Students who attended CCP schools reported eating lunch purchased from fast food outlets or other restaurants and drinking sugar-sweetened beverages (SSBs; soft drinks and sports drinks; sweetened coffee or tea drinks) on fewer weekdays, but consumed snacks from school vending machines on more weekdays, relative to students at open campus schools. No significant differences were observed in student reports of eating home-packed or school cafeteria lunches or snacks purchased off-campus.
CONCLUSION: CCP may help improve adolescent diets by reducing SSB and lunchtime fast food consumption on weekdays; however, students already purchasing food may shift from off-campus to within-school options, highlighting the importance of ensuring healthy school food environments and encouraging students to bring home-prepared lunches. Future studies using experimental longitudinal designs are needed to determine the effect of CCP on various health behaviours and outcomes.