Associations of mental health with subsequent weight development during a 4-year follow-up in adolescence

Impact- This study provides up-to-date, longitudinal evidence on how mental health shapes subsequent weight development during the critical and rapid growth period of adolescence. - Both adverse and protective dimensions of mental health play a role in shaping adolescent weight development, with evidence that some youths experiencing mental health difficulties exhibited smaller increases in BMI z-score, even when starting from a higher baseline weight status. -It should be acknowledged that in contemporary society, adolescents with emerging mental health difficulties may not necessarily present immediate excessive weight gain but instead follow stable or even declining weight trajectories. Although obesity and mental health problems represent two of the most pressing public health challenges, their developmental interplay remains insufficiently understood. Thus, we examined how depressive and anxiety symptoms, self-esteem, and psychological resilience are associated with weight development during adolescence. We included 1280 11-year-old children from the Finnish Health in Teens cohort, following 814 of them for 4.3 years. Mental health was assessed with validated self-administrated scales at age 11. Psychological resilience was determined by psychological health after exposure to stressful life events. Body mass index z-score (BMIz) and waist-to-height ratio (WtHr) were calculated at ages 11 and 16. Depressive and anxiety symptoms were associated with higher baseline BMIz but smaller increases in mean BMIz during follow-up (p = 0.009, p = 0.005, respectively). High self-esteem was associated with lower baseline BMIz, yet with steeper increases over follow-up (p = 0.002). Resilient adolescents showed lower baseline BMIz compared with non-resilient adolescents but exhibited greater increases during follow-up (p = 0.005). Similar trends were observed for WtHr. These findings highlight that mental health is associated with physical growth in adolescence, emphasising the need to consider mental health when seeking to understand and address patterns of weight development and their underlying dynamics.