Associations between eating jetlag and adiposity in preschool children, and the moderating roles of social jetlag and chronotype

PURPOSE: Eating jetlag (variation in eating times between weekdays and weekends) may increase obesity risk in adults, but studies in children are lacking. The potential moderating roles of social jetlag (SJL, variation in sleep timing between weekdays and weekends) and chronotype (an individual's intrinsic circadian rhythm) also remain unclear. We examined whether eating jetlag is associated with adiposity in Finnish preschoolers and whether chronotype or SJL moderate these associations. METHODS: Data included 639 children (3-6 years, 48% girls) from the cross-sectional DAGIS study (2015-2016). Diet was assessed using 3-day food records. SJL and chronotype were assessed from hip-worn accelerometer data. Six eating jetlag indicators were derived as weekend-weekday differences: first/last eating occasion jetlag, eating/energy intake midpoint jetlag and morning/evening latency jetlag. Adiposity was measured by BMI z-score and waist-to-height ratio (WHtR). Linear regression with interaction terms was used, with significant interactions examined in moderator-stratified analyses. RESULTS: Eating jetlag indicators were not associated with adiposity in the full sample. However, interaction analyses indicated moderation by SJL. Among children with high SJL (median 62 min, IQR 17), greater eating midpoint jetlag was associated with lower BMI z-score (β: - 0.65, 95% CI: - 1.21 to - 0.10), whereas greater morning latency jetlag was associated with higher BMI z-score (0.83, 0.19 to 1.46) and WHtR (0.035, 0.013 to 0.058). No consistent interactions were observed for chronotype. CONCLUSION: Although no associations were observed between eating jetlag and adiposity in the full sample, associations varied by SJL. However, these findings require confirmation in longitudinal studies.