5th September 2023 – by King’s College London

Children between the ages of 12 and 16 with a higher body mass index (BMI) are more susceptible to developing symptoms of depression, according to a recent study conducted by researchers from TwinsUK. The findings emphasize the importance of understanding the connection between mental health and weight in adolescence and suggest that early intervention strategies could be beneficial. 

The research, published in Psychological Medicine, used data from over 10,000 twins participating in the Twins Early Development Study (TEDS) and our TwinsUK cohort. Twins born between 1994 and 1996 self-reported depressive symptoms, including low mood, loneliness, and exhaustion, at ages 12, 16, and 21. The study’s key findings indicate a significant link between higher BMI and depression among individuals aged 12 to 16, with weaker association in the 16 to 21 age group. 

The team also found that children with a higher BMI during early adolescence were at an increased risk of developing depression later in life than those who experienced depression first and then saw an increase in their BMI.  

First author, Dr. Ellen Thompson explained: 

“Understanding the relationship between mental ill-health and weight in adolescence is vital to provide timely support where needed. This study shows a stronger association between having a higher BMI at age 12 years and subsequent depression symptoms at age 16 years than the reverse.” 

The study also highlighted that environmental factors played a significant role in the connection between BMI and depression at each age. While the study did not delve into the specific reasons for this effect, prior research has suggested that factors like body dissatisfaction and weight-related stigma from external sources could contribute to the association. 

Surprisingly, the study’s results remained consistent even after adjusting for socio-economic status, dispelling the notion from previous research that poverty might be the primary risk factor in this relationship. 

This shows the importance of early adolescence as a crucial period for addressing the potential consequences of higher BMI on mental health. Preventative measures, such as support structures and positive body image messages, could be incorporated into Personal, Social, Health and Economic (PSHE) education to counteract depressive symptoms in young teens. 

Co-senior author, Professor Claire Steves said: 

“Using the TwinsUK cohort, which focuses on older adult twins, our study showed that the relationship between BMI and depression was much weaker in later life. The exact reasons for these changes over the life course need further investigation.”