16/03/2014 15:12 GMT | Updated 16/05/2014 06:59 BST

Our Food Environment and Obesity

What is the link between takeaway food and obesity? It's a tricky question to answer because the evidence on it is mixed. But a recent paper in the BMJ provides some important new insights.

This new study looked at the eating habits and the weight of people who lived and worked in areas with lots of takeaways compared to people who didn't have as many takeaways within easy reach. They found that the first group tended to eat more takeaway food (like pizzas, burgers, fried food and chips) and that they were more likely to be obese - nearly twice as likely for people most exposed to takeaways.

What's distinctive about the study is that it analyses people's eating patterns in the context of where they spend their time: not just in their homes and neighbourhoods, but also at their workplace and on their daily commute from one to the other.

The study doesn't say that takeaways cause excess weight because you can't draw that kind of conclusion from this type of study. But in describing an association between the availability of fast-food on the one hand, and the odds of obesity on the other, research like this helps to focus attention on the role of the environment in shaping our health behaviours.

This is timely. The big shake-up in the public health system now gives local government the responsibility for protecting and improving the health of their communities. And among their top priorities is doing something about obesity, which affects one in four adults in the country and sabotages our health in many ways: by increasing both the risk of dying prematurely (from cardiovascular disease and some cancers) and the risk of developing chronic conditions like diabetes type 2.

Now, thanks to data published by Public Health England (PHE), local authorities can see how well they're doing at reducing levels of excess weight across their populations, compared to the national average (see map below).

Prevalence of excess weight (BMI≥25kg/m2) Adults aged 16 years and over


They don't just have the data. They also have the tools to do something about it, because, with public health, planning, transport, education and other sectors all under one roof, there are lots of different levers local government can pull to modify the environment so that it encourages behaviours we know promote health, such as nutritious, balanced diets and more physical activity.

Takeaways are part of this debate because we're eating more of our food outside the home than we used to - one in six meals and between 20% and 25% of calories come from eating out - and takeaway foods are a popular, but often unhealthy choice, because they tend to be high in salt and saturated fat and high in calories per gramme of food. It's well known that these types of diets contribute not just to obesity but to other problems as well, such as high blood pressure.

And it's not just what the takeaways sell, it's also where they are that matters: for example, there's a higher prevalence of outlets in areas with more deprivation (see chart).

Relationship between density of fast-food outlets and deprivation

(IMD 2010) - by local authority


Some local authorities have tried to use planning measures to restrict the growth of take-away outlets, especially near schools or close to other takeaways. There are also many things that can be tried to help takeaways improve the healthiness of the food they offer. For example, there's training in healthier frying techniques, schemes covering portion size, fats, sugar and salt as well as suggesting small changes, like reducing the number of holes in a salt shaker.

But, as many have pointed out, obesity is a complex problem. Tackling it is going to take much more than one type of action (even if we knew for sure that the presence of takeaways caused more people to eat unhealthily and gain weight, which we don't). First, there are lots of opportunities for people to eat unhealthily: just look at how many youngsters descend on local shops to buy sugary snacks and drinks on their way to and from school. And what about all the treats in work canteens? So we need to think about the wider food environment.

Second, we need to make it easier (and more fun) for people to move more: whether it's biking, taking the stairs, walking part of the way home. Increasing physical activity is the second half of the obesity equation: "too many calories in, not enough calories out".

What we're after is the cumulative boost to our health from lots of different changes - changes to our environment as well as the commitment we can make as individuals to become and stay healthy.