Early intervention key to prevention

Two of the main challenges faced by public health authorities throughout the world are obesity and mental health issues. A better understanding of the psychosocial factors that influence mental health and obesity in adolescents could support the development of preventive strategies to promote a healthy lifestyle.

A recent eClinicalMedicine study used the United Kingdom representative Millennium Cohort Study (MCS) to assess how happiness with appearance, dieting, bullying, and self-esteem mediates the relationship between mental health and body mass index (BMI) in adolescents.

Study: The role of dieting, happiness with appearance, self-esteem, and bullying in the relationship between mental health and body-mass index among UK adolescents: a longitudinal analysis of the Millennium Cohort Study. Image Credit: Monkey Business Images / Shutterstock.com

Background

Adolescence is a formative period that shapes an individual’s mental and physical health. Several studies have indicated a relationship between BMI and the manifestation of mental health disorders. In fact, obesity in children has been linked with the incidence of emotional symptoms, including anxiety, depression, aggression, and impulsivity during adulthood. 

Recently, bidirectional psychosocial mechanisms that link obesity with poor mental health have been identified. For example, an increased risk of low self-esteem and body image issues has been reported among obese adolescents, with an increase in weight also contributing to low self-esteem and poor body image. In addition, adolescents with body dissatisfaction and low self-esteem are at a higher risk of developing depressive symptoms. 

Body weight is a common factor for which young people are bullied, which can have a long-term impact on emotional symptoms through to adulthood. Mental health issues also increase the risk of being bullied in adolescence.

Previously, a cross-sectional analysis indicated that bullying is an important factor that mediates the association between weight gain and mental health; however, longitudinal analyses are needed to discern the direction of causation. To date, there remains a lack of studies that have explored the potential intervening pathways between mental health and obesity that account for longitudinal directional effects. 

Most studies suggest that, as compared to boys, girls are at a higher risk of obesity and mental health difficulties due to sociocultural pressures and beauty ideals. Therefore, overweight or obese girls are more vulnerable to mental health difficulties as compared to boys.

About the study

The current study used MCS, a prospective cohort comprising 18,818 children born in the U.K. between September 2000 and January 2002. Participants were randomly sampled from all four countries of the U.K.

All singleton children aged between 11 and 17 were included in this study. The emotional symptoms of each child were measured based on sex.

The current study hypothesized that for both boys and girls, a higher BMI at 11 years is linked with mental health difficulties by 17 years and vice versa. This association is mediated by increases in dieting, low self-esteem, happiness with appearance, and frequent bullying.

Study findings

Happiness with appearance and self-esteem, rather than dieting or bullying, mediates the relationship between BMI and mental health symptoms. Interestingly, both boys and girls showed higher emotional symptoms with an increase in BMI z score at 11 years, which was subsequently related to unhappiness with appearance and low self-esteem at 14 years. These boys and girls also exhibited externalizing and emotional symptoms by 17 years of age.

Longitudinally, for both genders, bullying was associated with mental health symptoms only, whereas dieting was only related to BMI. Notably, girls with a higher BMI at 17 years had externalized difficulties at 11 years. A similar quantitative association was documented between BMI, dieting, self-esteem, and happiness with appearance. 

Young individuals who tried restricting food intake or exercising were more likely to have gained weight later in adolescence. Furthermore, depression and anxiety were able to predict low self-esteem and unhappiness with appearance for boys and girls. Little evidence was found regarding bullying being the successor or predecessor of BMI.

Conclusions

One of the key strengths of this study is the utilization of a large representative U.K. cohort that made the findings generalizable to the wider population. Several mediators, including dieting, happiness with appearance, self-esteem, and bullying, were simultaneously assessed to analyze their effect on the association between mental health and obesity in adolescents. 

In the context of bullying, there is a possibility of bias due to its self-reported nature. However, it remains unclear whether the youth experienced low self-esteem only due to obesity. Therefore, in the future, a more comprehensive methodology is required to assess weight stigma.

Taken together, the study findings emphasize the importance of early identification of vulnerable groups for targeted intervention. Some vulnerable groups identified in this study include children experiencing emotional symptoms, tried dieting, or were unhappy with their appearance during adolescence, as they were at a higher risk of developing obesity than their peers. Earlier mental health symptoms of impulsivity and aggression were also associated with later BMI for girls, while increases in BMI were linked with later symptoms of anxiety and depression for boys.