This story has been adapted from an Imperial College London press release
Promoting positive body image and self-esteem among children could help to reduce poor mental health associated with being higher weight in adolescence.
These are the findings of a study of more than 12,000 children in the UK in which researchers from the School explored the impacts of psychological and social factors on the relationship between mental health and body mass index (BMI) throughout adolescence.
The link between children having a higher weight and being more likely to have poor mental health outcomes is well established. The proportion of young people with obesity with emotional difficulties, such as depression and anxiety, is around twice that observed for young people with a healthy BMI (19% vs 10%).
But in the latest study, researchers found that increasing children’s satisfaction with their appearance and self-esteem from early adolescence could help to protect against the negative impacts of having higher weight on their mental health.
Using data collected when young people were 11, 14 and 17 years old, they measured a range of factors including how adolescents felt about their appearance, self-esteem, experience of bullying and dieting, along with BMI and mental health difficulties.
They found that at a population level, children’s happiness with their appearance and their self-esteem had the greatest influence on the relationship between BMI and mental health, further compounding poor mental health into their late teens.
The study found that 11-year-old children at higher weight were more likely to have poor body image and lower self-esteem as they entered their teens, than those with average weight. Subsequently, both boys and girls unhappy with their appearance and with low self-esteem at age 14 were more likely to have mental health difficulties at age 17, such as anxiety, depressive symptoms, aggression, and impulsivity and were also likely to have a higher BMI than those with a more positive self-image.
According to the authors, their study published in the journal eClinical Medicine is the largest of its kind and provides the most representative snapshot of these population-level trends of psychosocial factors in UK children.
They say prevention strategies in the national curriculum, industry and on social media platforms to destigmatise weight and encourage healthy body image in children are needed to help alleviate a range of negative social and emotional problems in later years.
Dr Hanna Creese, SPHR researcher from Imperial College London, and first author of the study, said:
“The links between mental and physical health are well established, and we know that children who are overweight or obese are much more likely to suffer social and emotional problems, such as depression and anxiety. But unpicking the different factors driving these outcomes is challenging – such as the complex two-way relationship between mental health and BMI.
“It’s important for children to maintain a healthy weight, but our study highlights that this shouldn’t be achieved at the expense of children’s long-term mental health or by stigmatising their weight and driving poor body image and low self-esteem, as this can have damaging and long-lasting impacts.”
In the analysis, researchers analysed data from the Millennium Cohort Study, a nationally representative dataset capturing information on almost 19,000 children born in England, Scotland, Wales and Northern Ireland between 2000–2002. They included data on 12,450 children, from the age of 11 years up to and including the age of 17 (in 2018). Data included measures of BMI (kg/m2) standardised by sex and age (BMI Z score), parent reported scores from a validated questionnaire on young peoples’ mental health and dieting behaviour, happiness with appearance, self-esteem, and experience of being bullied reported by young people themselves at age 14 years.
Body image and self-esteem
The analysis revealed children’s happiness with their appearance and self-esteem go some way to explain the impact of being higher weight on risk of mental health difficulties. Each increase in BMI Z score at 11 years old was associated with an increase in scores of unhappiness with appearance (0.12 for boys, 0.19 for girls) and an increase in odds of low self-esteem (16% for boys, 22% for girls) at age 14. At age 14, both girls and boys who were unhappy with their appearance and had lower self-esteem were more likely to have emotional and social symptoms at age 17, such as anxiety, depressive symptoms, aggression, and impulsivity.
Obesity, dieting and bullying
The study showed the association between increased BMI and mental health. Obese children had a greater prevalence of emotional problems at age 11 compared to healthy weight children (18.9% vs 10.3% for boys; 18.7% vs 10.8% for girls). Being a higher weight is a well-established common reason for childhood bullying, and the analysis showed children who reported frequent bullying were more likely to have poor mental health outcomes over adolescence than those who were not bullied. But there was no significant link between being a higher weight and frequent bullying, or being bullied impacting later weight status. The analysis also found that dieting behaviours were associated with higher BMI, but not with worse mental health outcomes.
Measures to destigmatise weight
According to the authors, there are a range of established interventions to reduce obesity and improve mental health among young people – such as campaigns to promote healthy eating at home and in school, as well as apps and phonelines to encourage children to access mental health support. However, the promotion of positive body image and self-esteem among young people in education and the media would benefit both physical and mental health in the UK population. For example, limiting children’s access to social media encouraging unrealistic or unhealthy body image, and lessons on positive body image at school.
Dr Dougal Hargreaves, SPHR researcher and senior author of the study, said:
“Adolescence is an important stage when the foundations of lifelong patterns of mental health and weight are laid, investing in the right support for young people during this critical window of development can lead to lifelong health and economic benefits. This study suggests that reducing weight stigma during adolescence could be one important step to improving long term outcomes.
“It’s important to remember children today are not growing up in the same world as their grandparents, or even their parents, and face new, and increased social pressures. If we really want the best for our children, we need to put our money where our mouth is and promote healthy behaviours and attitudes at the societal level.”
Dr Dasha Nicholls, child psychiatrist and eating disorders expert, from Imperial College London’s Department of Brain Sciences, said:
“Children at higher weight are at greater risk of mental health problems including eating disorders, for which poor body satisfaction and dieting are well established risk factors. This study adds to the evidence that supporting young adolescents to have a positive body image and developing confidence and self-esteem is important for both their mental and physical health in the longer term.”
The authors highlight that the trends seen in the analysis are broadly applicable to the population level but cannot be used to predict outcomes for individual children. They also stress that this study did not focus on the direct impact of social media on body image or self-esteem but acknowledges its strong influence. As the cut off for the data collection was 2018, it does not account for increased social media use among children and teens in recent years or during the COVID-19 pandemic.
The research was funded by the National Institute for Health and Care Research (NIHR) School for Public Health Research.
‘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’ by Hanna Creese, Sonia Saxena, Dasha Nicholls, Ana Pascual-Sanchez, and Dougal Hargreaves is published in eClinical Medicine. DOI: https://doi.org/10.1016/j.eclinm.2023.101992
NOTES TO AUTHORS:
 The Millennium Cohort Study is nationally representative study following the lives of around 19,000 young people born across England, Scotland, Wales and Northern Ireland in 2000-02. It provides multiple measures of physical, socio-emotional, cognitive and behavioural development over time, as well as detailed information on daily life, behaviour and experiences.
For more information, visit the MCS website:
 BMI-Z is a measure of how many standard deviations a child or young person’s BMI is above or below the average BMI for their age and gender. For example, a BMI Z score of 1.5 indicates a child is 1.5 standard deviations above the average value, and a BMI Z score of -1.5 indicates a child is 1.5 standard deviations below the average value.
About Imperial College London
Imperial College London is a global top ten university with a world-class reputation. The College’s 22,000 students and 8,000 staff are working to solve the biggest challenges in science, medicine, engineering and business. The Research Excellence Framework (REF) 2021 found that it has a greater proportion of world-leading research than any other UK university, it was named University of the Year 2022 according to The Times and Sunday Times Good University Guide, University of the Year for Student Experience 2022 by the Good University Guide, and awarded a Queen’s Anniversary Prize for its COVID-19 response. https://www.imperial.ac.uk/
About the National Institute for Health and Care Research (NIHR)
The mission of the National Institute for Health and Care Research (NIHR) is to improve the health and wealth of the nation through research. NIHR do this by:
- Funding high quality, timely research that benefits the NHS, public health and social care;
- Investing in world-class expertise, facilities and a skilled delivery workforce to translate discoveries into improved treatments and services;
- Partnering with patients, service users, carers and communities, improving the relevance, quality and impact of our research;
- Attracting, training and supporting the best researchers to tackle complex health and social care challenges;
- Collaborating with other public funders, charities and industry to help shape a cohesive and globally competitive research system;
- Funding applied global health research and training to meet the needs of the poorest people in low and middle income countries.
NIHR is funded by the Department of Health and Social Care. Its work in low- and middle-income countries is principally funded through UK Aid from the UK government.