Public health authorities worldwide face two significant challenges: obesity and mental health issues. To develop strategies that promote healthy lifestyles and prevent obesity and mental health problems in adolescents, it is crucial to understand the psychosocial factors that influence them. The Millennium Cohort Study (MCS), a representative UK cohort, was used in a recent eClinicalMedicine study to explore how physical appearance, diet, bullying, and self-esteem wellbeing influence the relationship between mental health and body mass index (BMI) in adolescents.
Several studies have linked BMI to the onset of mental health disorders, with childhood obesity associated with emotional symptoms such as anxiety, depression, aggression, and impulsivity in adulthood. Bidirectional psychosocial mechanisms have been identified linking obesity and poor mental health, including low self-esteem and body image problems among obese youth, which also contributes to poor mental health. Being dissatisfied with their bodies and having low self-esteem increases adolescents’ risk of developing depression symptoms, while weight is a common factor in youth bullying that can result in psychiatric symptoms lasting well into adulthood.
It is suggested that sociocultural pressures and beauty ideals put girls at higher risk of developing obesity and mental health problems than boys. The study hypothesized that higher BMI at age 11 would be associated with mental health difficulties at age 17 and vice versa, in both boys and girls and would be mediated by increased dieting, lower self-esteem, appearance wellbeing, and frequent bullying.
The findings indicate that appearance and self-esteem wellbeing mediate the relationship between BMI and mental health symptoms, rather than diet and bullying. Both boys and girls showed higher affective symptoms with increasing BMI z-score at age 11, subsequently resulting in poorer appearance and lower self-esteem at age 14, with these boys and girls exhibiting externalization and emotional symptoms by age 17. Over time, bullying was associated only with mental health symptoms, and dieting was associated only with BMI in both men and women. Girls with a higher BMI at age 17 had externalized difficulties at age 11.
The study confirms that adolescents who try dieting and exercise are more likely to gain weight in late adolescence, and depression and anxiety predict lower self-esteem and unhappiness in appearance in boys and girls. Although bullying was found to be associated only with mental health symptoms, it remains unclear whether young people experience lower self-esteem due to obesity alone. Overall, the research underscores the importance of early identification of vulnerable groups for targeted intervention who are experiencing emotional symptoms, trying to diet, or are dissatisfied with their appearance during adolescence, as they are at a higher risk of becoming obese than other children.