Irregular meal pattern and later sleep midpoint are associated with increased BMI -score and waist-height ratio during early adolescence.

Background: Rapid gains in adiposity may have more adverse health implications in later life compared with having stable adiposity throughout childhood and adolescence. A knowledge gap concerns concomitant health behaviors contributing to adiposity gain among adolescents.

Objectives: We investigated the associations of health behaviors relating to dietary habits, sleep, physical activity (PA), and screen time with an increase in body mass index -score (BMIz) and waist-height ratio (WHtR) during adolescence.

Methods: We included 4,785 adolescents (53% of girls) aged 11.1 (SD 0.8) years at baseline and followed them for 3 years. We clustered them into decreased, stable, and increased BMIz and WHtR categories using the K-means clustering method. Using Cox regression, we computed hazard ratios (HR) with 95% CI for the associations of self-reported health behaviors (dietary habits, physical activity, sleep midpoint, and sedentary digital media use) with belonging to an increased BMIz or WHtR group. In a subsample ( = 3,840), we ran a sensitivity analysis considering puberty status as an additional covariate.

Results: Later sleep midpoint (having later midpoint of sleep between bedtime and waking time) and irregular meal pattern (not eating lunch and dinner every school day) predicted increased BMIz (HR 1.26 [95% CI 1.13-1.41] and 1.23 [1.08-1.39], respectively) and WHtR (1.23 [1.09-1.39] and 1.18 [1.02-1.36], respectively) over the follow-up period, after adjusting for other health behaviors. Associations remained after considering puberty status as a covariate.

Conclusions: Early bedtime with adequate sleep duration and regular meal pattern should be encouraged to prevent adiposity gain during early adolescence.