This report describes the findings and methods of a systematic review of research which explores the relationship between obesity and educational attainment. It has been conducted at a time of great concern about levels of obesity in the UK, and the negative physical, psychological and social impacts of obesity. Current research suggests that there may be a relationship between obesity and poor educational attainment. It is likely that obesity and poor school performance are elements of a broader picture of inequalities in health and education, whereby disadvantaged socio-economic groups tend to have poorer health and lower levels of education. However, it is possible that other factors influence obesity and attainment, such as gender, discrimination and poor mental and emotional well-being.
This systematic review was therefore commissioned to address the question: What do we know about the relationship between childhood obesity and educational attainment, from the research literature? In order that our review might be informed by those closest to observing any interaction between obesity and attainment, we sought the perspectives of teachers and young people to identify the causal pathways that seemed most pertinent to them.
Is there a statistical association between obesity and educational attainment?
While often conflicting, an overall pattern emerges from the research evidence suggesting that there is a weak negative association between obesity and educational attainment in children and young people; i.e. that higher weight is associated with lower educational attainment. Obesity is also associated with other variables, such as socio-economic status, and when these other variables are taken into consideration, the association between obesity and attainment becomes still weaker, and often loses statistical significance.
To what extent does the research evidence explore the influence of the broader determinants of health, and in particular socio-economic position, in explaining any link between obesity and attainment?
Place of residence, ethnicity, occupation, gender, religion, education, socio-economic status (SES) and social capital were all explored as potential moderating variables in the included research. Twenty-three of 29 studies used a measure of socio-economic status as a moderating variable. Various factors appear to contribute to low educational attainment to some extent, although given the variation in definitions, analyses and quality of data, it is impossible to point to any causative or definite risk factors.
Authors of the included studies have posited theories suggesting that the link between obesity and educational attainment is moderated by individual and societal factors. Does the research evidence support or refute these?
Most studies explored the influence of obesity upon attainment. Only two studies examined the influence of attainment upon obesity. Many authors suggested multiple causal pathways, many of which remained untested in their studies. The moderating variables used in statistical analyses of the relationship between obesity and attainment were not consistent with the causal pathways proposed, which is probably a reflection of the constraints imposed upon authors conducting secondary analyses of pre-existing datasets (i.e. they made use of existing variables, rather than collecting their own, tailored data). The most frequently cited factors resulting from obesity and impacting upon educational attainment were poor mental health, stigmatisation and discrimination, disordered sleep, decreased time spent in physical activity and socialising, and absenteeism.
Different perspectives on obesity and attainment
Few young people initially thought that obesity and educational attainment were associated. However, they considered obesity and educational attainment to be of importance to young people. Young people considered parental influence and circumstances, including family income and poverty, and bullying and emotional health to be the most important factors which might explain an association between obesity and educational attainment.
Most teachers said that there was an association between obesity and educational attainment. Bullying, low self-esteem and emotional well-being, poverty and poor diet, and physical activity were commonly cited by teachers as being the most important and credible mediating variables in this association. Teachers also considered gender, ethnicity and parental influence to be important factors.
While researchers, teachers and young people identified causal pathways whereby low academic attainment resulted from poor mental and emotional health among obese children and young people, only four studies adjusted for mental and emotional health variables. This may represent a significant divergence in the perspectives of researchers and stakeholders. Alternatively, it may be that in the 23 studies which conducted a secondary analysis of an existing dataset, such data were not available to the authors. Another divergence concerns the impact of reduced participation in sports and social activities. While teachers and young people located this within a broader framework of isolation and lower socialisation suffered by obese children – and thus felt reduced sports participation would result in lower attainment – three studies in the included research proposed a causal pathway in which reduced participation in sports and social activities might lead to increased time spent studying and hence higher attainment.
There are three important implications arising from this review:
First, that obesity should not be understood solely as a health issue. This review, and other research, suggests that one of the most noticeable ways in which obesity affects the lives of children and young people is in their social relationships. Given the paucity of evidence suggesting a causative physiological link between obesity and attainment, any association is likely to be mediated by social factors. We find that stigmatisation, bullying, low self-esteem and young people’s exclusion from opportunities for social interaction are suggested as underlying any relationship between obesity and lower educational attainment.
Second, that the variables used in statistical analyses failed to capture many of the potential causative factors identified by the teachers and young people (and, often, also of the researchers undertaking those analyses). If large-scale longitudinal datasets are to deliver on their potential to help us understand people’s lives, they need to engage with the social lives of their participants and amass not simply data that are straightforward to collect, but information that reflects determining characteristics of people’s social experiences, because these are often the key to understanding health and other behaviours.
Finally, we find this body of literature to be one of the least cumulative that we have reviewed. Data from the same datasets are analysed in different ways, using different variables, coming to different conclusions with minimal attempts to explain differences in findings. Different statistical models are sometimes employed with little justification for their selection and little acknowledgement that a different method might yield an entirely different result. These are important failings, and it is hoped that work associated with the EQUATOR network will in time lead to improvements (Simera et al. 2010). We should note that these criticisms do not apply to all studies in this review, but it would be true to say that they do apply to many of them.
This report should be cited as: Caird J, Kavanagh J, Oliver K, Oliver S, O’Mara A, Stansfield C, Thomas J (2011) Childhood obesity and educational attainment: a systematic review. London: EPPI Centre, Social Science Research Unit, Institute of Education, University of London.