Obesity is linked to where you live – would regulating fast food outlets change this?
The type of neighbourhood you live in predicts how likely you are to be obese, our latest research shows. And it's a bit more complicated than some might assume.
Obesity is associated with a range of diseases, such as type 2 diabetes, cardiovascular disease, arthritis and some cancers, so finding ways to stop people becoming obese is important for public health and for the public purse. More than a quarter of people in the UK are obese, but levels of obesity vary by region. We wanted to investigate the characteristics of an "obesogenic" environment – an environment that encourages weight gain – specifically, the combined factors of easy access to food and availability of places to exercise.
For our study, we split residential areas in Yorkshire, England, into five types, based on the number of food outlets and opportunities for physical activity: saturated; moderate availability; low availability; moderate physical activity, limited food; and moderate physical activity, ample food.
Our analysis showed that only two of the neighbourhood types were associated (negatively and positively) with obesity. Saturated neighbourhoods, which are characterised by a high availability of fast-food outlets, convenience stores and supermarkets as well as a high availability of gyms and parks, were associated with a 14% lower risk of obesity.
While moderate availability neighbourhoods – those characterised by a moderate number of food outlets and places to exercise – were associated with an 18% higher risk of obesity.
Saturated neighbourhoods have features that are both obesity promoting and constraining. They have a high density of fast-food outlets, but also a high density of places to exercise. What gives?
The lower risk of obesity in these neighbourhoods might be explained by population density. Saturated neighbourhoods were predominantly urban and densely populated. An earlier study of 419,000 UK adults in 22 cities showed that densely populated urban areas are associated with a lower risk of obesity, and moderately populated areas are associated with a higher risk of obesity.
People who live in the moderately populated suburbs – the so-called suburban sprawl – may be more likely to get in their car and drive to friends, work or the shops. But, in the heart of the city, everything is much more walkable. This increase in walking may partly explain the lower rates of obesity in densely populated areas.
And there may be factors that explain the link between the moderate availability of exercise facilities and higher rates of obesity. In our study, we didn't capture the quality of the public spaces that could be used for exercise. Living near a park may offer opportunities to jog or take a dog for a walk, but if people feel unsafe in those spaces, they may avoid them.
Many environmental influences
Regulating fast food outlets by restricting planning applications is one policy option to reduce obesity levels – a strategy recently adopted by London's mayor, Sadiq Khan. But this seemingly simple solution is – as our research shows – not so simple.
It fails to acknowledge many other environmental influences. For example, the number of fast-food outlets in an area is restricted by the local council, people will still be able to buy unhealthy food from convenience stores or supermarkets. Also, restricting fast-food outlets does nothing to change the availability – or quality – of places to be physically active.
While we don't dispute the link between fast food and obesity, our study highlights the multidimensional, nuanced nature of obesogenic neighbourhoods. Moving beyond regulating fast-food outlets to consider other aspects of the neighbourhoods we live in will help provide healthier environments.