Abstract
While adolescence is a key period to shape healthy lifestyles, overweight/obesity and mental health problems are both prevalent among adolescents worldwide, yet evidence on physical activity and mental health remains limited for adolescents with overweight/obesity, particularly regarding gender and day type (weekday vs. weekend). We analyzed 1,238 adolescents with overweight/obesity from the UK Millennium Cohort Study (45.3% boys; M age = 14.25 years, SD = 0.34). At age 14, accelerometer-measured MVPA was assessed separately for one weekday and one weekend. At age 17, internalizing and externalizing problems were assessed using SDQ subscales. Associations were examined using survey-weighted negative binomial regression, with SDQ scores modeled as count outcomes. Models adjusted for sociodemographic, family, cognitive, and baseline mental health factors, and analyses were stratified by gender and day type. On weekdays, higher MVPA was associated with fewer internalizing problems among girls (IRR = 0.988, 95% CI [0.978, 0.997]), but not boys, corresponding to about 1.2% lower symptom rate per 10 min additional MVPA per day. On weekends, higher MVPA was associated with fewer internalizing problems in the overall sample (IRR = 0.992, 95% CI [0.984, 1.000]), corresponding to about 0.8% lower symptom rate per 10 min additional MVPA per day. No significant associations were found for externalizing problems. Higher MVPA was associated with modestly lower internalizing problems among adolescents with overweight/obesity, although effect sizes were small and patterns varied by gender and day type. Contextual factors may be important in understanding these associations.