Living near take-aways can make you fat

Tom Burgoine published a paper this week in the British Medical Journal titled, "Associations Between Exposure to Take-away Food Outlets, Take-Away Food Consumption, and Body Weight in Cambridgeshire." Chris Smith caught up with him to find out the reason behind it

Tom - Well we know that levels of obesity in the UK are a major problem, but that obesity itself is kind of complex and multi-faceted. What we really wanted to do is explore the neighbourhood environment contribution to obesity and unhealthy diets. Really, I mean, you might say to me, isn't it obvious that neighbourhoods matter for health and that neighbourhoods matter for what we eat. What I'd say really is that, up until now, we haven't had the opportunity to answer that question scientifically and to really try and find the scientific answer.

Chris -  So, people had some idea that there must be an association between retail outlets selling fast-food and people potentially gaining a bit more weight. But there was no objective data on it.

Tom - There was no objective data, exactly. It seems like common sense, but when you think of the implications for something like this where we're talking about modifying neighbourhoods potentially to make them more healthy, to help people make healthier choices, we really need those to be evidence-based decisions.

Chris - Some rock-solid data to go on. So, how did you do this?

Tom -  Well basically, we took data for 5,500 individuals in Cambridgeshire and we counted the number of takeaway food outlets around where they lived, around where they worked, and around their journeys from home to work. So, we had kind of a measure of overall exposure to takeaway food outlets and then we also knew how much these people weighed. We knew their body mass index and we knew how much takeaway food they consumed. So, we kind of put those two things together, tried to see to what extent their exposure would explain those two outcomes.

Chris - What did you find?

Tom - People with the greatest overall access to takeaway food tended to be heavier.  So, they tended to have a body mass index, more than those least exposed by over a unit. They were also nearly twice as likely to be technically obese and they would consume on the whole around 6 grams of additional takeaway food per day which over the course of a week is about half a portion of french fries.

Chris - But over a lifetime which I mean, people pile on weight gently. They don't suddenly become overweight. So, that actually - it doesn't sound like much but actually, extrapolated to - you've lived somewhere for 5 years could actually add up to quite a significant weight gain then.

Tom - Yeah, absolutely. Even that small daily increase. It's still 2 extra kilograms of takeaway food per year. Exactly, it's about a repeated exposure and a repeated behaviour.

Chris - How did you work out what people were being exposed to on the way to work? Because that doesn't sound trivial.

Tom - We kind of made a best guess really and said that they travelled from their home to their work along the shortest route along the street network which we allow to differ depending on how they travel to work, and the mode of travel and how frequently they use the mode of travel. It was an educated guess.

Chris - And that tells you the route they took. What about the number of retail outlets that they would've seen then along that route?

Tom - Okay, so we kind of drew a buffer around that route and counted the number of food outlets. We allowed that buffer if you like to vary depending on how they travel. So, if they travel by car, we said they had greater exposure on their route because they're presumably traveling faster than if they're walking.

Chris - If they're hungry, they might be going really fast.

Tom - Absolutely.

Chris - But what did you find was the main determinant then? Was it the workplace, was it the route to work or was it the home?

Tom - Yeah, so we looked overall exposure, but yeah, we looked at domain specific exposure as well. Workplace seemed to be particularly important. So, these associations were particularly strong with workplace exposure. And I guess really, that again makes sense if you think about the types of foods you want when they're at work, you probably want ready prepared food, the kind of foods takeaway food outlets are selling. And also, you've probably got a limited amount of time to take for lunch. So, more proximal food outlets might be more important in that sense.

Chris -  Does it not also just reflect where people spend the most time? So, if those workers became unemployed, would the home environment become a stronger determinant compared with the workplace?

Tom - We were looking at home and work particularly because people spend a lot of their time in those two neighbourhoods. The characteristics of the sample used actually meant that we didn't really have that many unemployed people so we weren't able to look at that modification and look at unemployed people in particular to see about that neighbourhood influence, the home neighbourhood. That's something that we'd like to do, but something we couldn't do on this occassion.

Chris -  Has this generated the sort of objective data that you were hoping it would so that you can now say, "What we need to do in order to encourage people to have a healthier life is X." Are you in that position now?

Tom - This is really a first step. So, this is a large study. This is the biggest study as far as we know and the most comprehensive study of this type, in the field so far. But really, it's a hint of this association and a call to do more research. What it could lead to of course is supporting changes, modifying neighbourhood environment in some way to help people make healthier food choices and help maintain a healthier weight. But really, we need a firm evidence based through that and this is the first piece of the puzzle.

Chris - I wonder if it will reflect on house prices. People could begin to market their house. The asset value of their house will increase if there are not obesity risks in the near vicinity.

Tom - Yeah, you're not the first person to suggest that.

Chris - Really?

Tom - Yes.