How can schools help prevent childhood overweight and obesity?

A ‘realist review’ of primary school-based studies in childhood obesity prevention has shed light on the factors that could make an intervention effective. Published in the International Journal of Environmental Research and Public Health, it revealed the factors that influence whether an intervention is successful, as well as demonstrating that education alone – such as teaching young children about healthy eating – may not work.

Childhood obesity has been increasing rapidly in the UK for the last 30 years, and dramatically so over the last 18 months as a result of COVID-19 restrictions. Now, one in four children start school with overweight or obesity and 40 per cent leave school with overweight or obesity (NHS Digital, 2021). Schools alone cannot improve children’s health, but this setting presents an important opportunity for intervention.

A summary of childhood obesity studies is available in a Cochrane Review, which members of the ARC West team helped to publish in 2019. It includes the results from 153 studies, many of which were delivered in school settings, to children aged 4-18.

The results from the Cochrane Review show that some of these interventions help children maintain a healthy weight. However, the interventions are often complex and very different from each other. This means it isn’t easy to tell which elements of an intervention might work, for which groups of children, and in which circumstances it might work best.

A ‘realist review’ is a research method that can help answer some of these questions. This realist review found that being older, being a girl and having educated parents seemed to be important background factors for many interventions to work. However, this could have negative implications for widening health inequalities.

Factors underpinning the effectiveness of an intervention were:

• How regular and long the children were exposed to the intervention for (dose)
• Changes in the environment, such as changing canteen food options or layout, or installing water fountains
• The parts of an intervention working together as a whole to be more effective than the sum of its parts

Educating children about health alone was not a feature that seemed to lead to positive change.

The research team recommend that obesity prevention in primary schools should go beyond health education. This is important because most interventions to date are centred around educating children to make healthier choices, as was found in another of our .

Sharea Ijaz, Senior Research Associate at ARC West and lead author of the paper, said:

“We found that interventions need to be intense or long enough – think in terms of its ‘dose’ – to have the desired effect of promoting a healthy weight in children. Environmental changes, such as changing the food available or the layout of the food in the canteen, enabled healthier choices by providing alternative opportunities without pushing responsibility onto the child.

“We found a large set of decent quality data which collectively indicates that we need to look beyond education interventions targeting behaviour change in young children, as they have little agency. We should instead consider doing things that enable them to choose healthy behaviours.

“When obesity prevention interventions are being developed, we should involve children, their parents and school staff and pay attention to background factors such as the socio-economic status of children or the existing level of obesity in the school. This will help avoid widening health inequalities.”

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