Photo credit: (c) World Obesity
Expressively characterising the influence of the environment, the term ‘obesogenic’ (an environment that hinders sufficient physical activity and promotes excessive intake of food, thereby making obesity more likely to occur) is commonly used. This concept is not new; 15 years ago it was suggested that interventions to create less obesogenic environments present relatively low-cost means to help reduce obesity. More recently UK policy makers have engaged with this idea and have actioned decisions on things such as the location of fast food outlets. For instance, in November 2017 the Mayor of London announced a total ban of fast food takeaways opening within 400 metres of schools in the city - Evening Standard.
While most agree that such decisions are unlikely to have negative effects in terms of obesity, a concern is that the evidence base to support such decisions being protective [of obesity] is equivocal at best.
The concept of an environmental effect on obesity is intuitively appealing. The idea that how close you live to a fast food outlet or a local park could influence your likelihood of gaining weight seems a logical one. However, identifying the actual role (over the assumed role) of the environment is central to improving the prevention and treatment of obesity. Proximity is not the only determining factor when it comes to a person choosing where to buy their food or whether or not they will be physically active. Other factors are also likely to play a role, such as cost, available modes of transport, personal values, and social support, to name a few.
There is considerable debate in the literature about the relative importance of people and/or place characteristics to predict health related outcomes. Most empirical studies have concluded that where you live matters for health, although probably not as much as who you are. However, it has also been suggested that improvements in public health will be achieved by a greater focus on place. It is possible that the failure to find consistent associations may be due to methodological challenges. Researchers and practitioners face a myriad of methodological questions, which have considerable consequences for the interpretation of outputs, yet are seldom discussed or considered. There seems to be a focus on headline statements, which in some instances are unqualified or misguided leading to policy decisions that are not evidence based – such as banning fast food takeaways from opening around schools.
When we consider obesity as the outcome (rather than health related outcomes more broadly) the evidence in relation to the food environment is equivocal and not well placed to support some of the recommendations currently being proposed. This is not to say that practitioners should wait for the evidence to provide the answer. There are many examples of innovative thinking and novel approaches from around the UK, and these practices should be encouraged. However, what is often missing is robust evaluation. For example, a robust evaluation of the actual impact of fast food takeaway bans on the prevalence of childhood obesity is needed. Evaluations such as these will ensure that researchers and practitioners learn from best practice and inform the evidence base along the way. This will require collaborative working across multiple disciplines and sectors, in order to identify the actual role of the environment in the prevention and treatment of obesity.