Tuesday, July 06, 2010

Built environments impact on obesity through food, not fitness.


Chalk up another causal win to food in the battle of what's responsible for our current obesity epidemic - this time in the arena of built environment.

Built environment is the term given to the neighbourhood you live in. It has to do with things like walkability, parks, bike paths, sidewalks and all the various and sundry that city planners can do to try to shape your use of where you live.

Built environment is also a hot button issue at obesity conferences with researchers trying to find ways to get people moving more through smarter urban planning.

My belief is that casually moving more doesn't matter too much with regards to obesity. There's simply no amount of sidewalks or bike paths or beautiful parks that you could put in a neighbourhood to help with the issue of obesity because obesity is primarily about energy intake, not energy output, and really no amount of leisurely strolling is going to negate our horrendously calorific food environment.

But built environment does matter. What matters about the built environment though is food and how close you are to it, and what type it is.

In a study published this month in the Journal of Planning Education and Research Samina Raja et al looked at the influence of built and food environments on 172 women's BMIs in Erie County New York between 1999-2004.

What did they find?

1. The more restaurants within walking distance the higher the BMI (p=0.037).

2. The closer you live to a healthful food destination (supermarket), the lower the BMI (p=0.025).

3. Walkability didn't make one whit of difference.

Interestingly the authors listed the fact that they didn't know the types of restaurants as a limitation and suggested that there might be healthier ones. I'd argue, with exceedingly rare exceptions, restaurant food, regardless of whether it's sit down, stand up, casual, or fancy, has non-intuitively, astronomically large numbers of calories.

Ultimately what matters isn't the sidewalks, it's where they take you.

Raja, S., Li Yin, ., Roemmich, J., Changxing Ma, ., Epstein, L., Yadav, P., & Ticoalu, A. (2010). Food Environment, Built Environment, and Women's BMI: Evidence from Erie County, New York Journal of Planning Education and Research, 29 (4), 444-460 DOI: 10.1177/0739456X10367804

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12 comments:

  1. Yoni,

    It is the environment. However, not the environment you are discussing. Now that I am a "professional" observer of people, two things have become abundantly clear:

    1. My unscientific, but educated guess is that 90% of people are overweight. Thus, people who are diet, fitness, and health conscious are in the minority. This makes the health-oriented people seem to be the "odd-balls".

    2. People who are overweight and unfit don't seem to care. Pizza, ice cream, chips and more are much more important to them than health.

    While I am actively promoting my diet and health book, and do want people to maintain a healthy lifestyle, I actually enjoy being in this minority.

    Ken Leebow
    http://www.feedyourheaddiet.com

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  2. Anonymous11:13 am

    1. Suburbs have fewer restaurants than city areas, are suburbanites less obese?

    2. Number and variety of restaurants is a positive aspect of city life for some people, planners and tourism promoters and real estate agents. Restaurants are supposed to add sophistication and diversity. They're supposed to be a community focus, a cultural benefit.

    If it turns out all these restaurants are just making people fat, what will we do for a sophisticated urban lifestyle?

    Sigh. Brown-bagging a PB & J just doesn't cut it.

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  3. Not sure what the prior commenter's post isn't showing up but they'd asked about suburbanites.

    This study didn't look at suburbanites so tough to say.

    No doubt brown bagging PB&J isn't as glamourous as a meal out.

    That said, life ain't always fair and with regards to calories, I'd say it's virtually never fair.

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  4. I emailed the author of this study. Not sure why you made any reference to fitness here. This study pertains only to distance to food and type of food. They did not look at what exercise inhabitants were doing or not, nor did they try to compare exercise with food intake as an impact on obesity. This is a food article?

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  5. Nor should they have Mavis.

    This study was looking at the impact of environment on BMI.

    Most studies (and public health folks) suggest if we could just make neighbourhoods more "walkable" people would lose weight.

    This study indeed did look at walkability index and found no linkage to BMI. The linkages they did find were those related to food.

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  6. Anonymous11:49 am

    I respectfully disagree with the tone of this post - I know the focus of this blog is obesity. And that walkability doesn't inherently mean that someone will not be obese. But there is more that matters about the built environment than, simply, the type of food in it. Where jurisdictions put their money for infrastructure - whether it's in sidewalks, bike paths, city or rural parks/open spaces, how well that is designed, and who benefits - whether that is equal among populations or not - all does contribute to overall health. The food environment, like the built environment, are inherently social justice issues, and both can impact health (which is not just obesity, but emotional, mental, and physical).

    There are many benefits to having a friendly built environment. I just didn't want that to get lost in the tone of the post. Thanks.

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  7. Yoni, In Obesity Reviews was published yesterday about A systematic review of environmental factors and obesogenic dietary intakes among adults: are we getting closer to understanding obesogenic environments?
    Conclusion? Well not in agreement with you.
    The environment may play an important role in the development of overweight/obesity, however the dietary mechanisms that contribute to this remain unclear and the physical activity environment may also play an important role in weight gain, overweight and obesity.
    I guess you are not being blogging about it because it is in contradiction with your point of view... http://bit.ly/bek6dY

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  8. Or maybe because I haven't read it?

    Have you read every article published yesterday?

    I didn't think so.

    Or maybe because I don't want to?

    You more than anyone should know that people choose to write about the things that interest them.

    I've been very clear on my blog about what my confirmation biases are - have you?

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  9. Having now read the study Paul, it makes me wonder if you did given that the authors findings included,

    "Weight status was most consistently associated with features of the environment; residents of areas with greater access to supermarkets or lower accessibility to takeaway outlets had a lower prevalence of overweight/obesity compared with those living in areas with limited supermarket access or a greater accessibility to takeaway outlets"

    And then to explain some confusing results (results are often confusing when combining multiple studies with different designs - a limitation the authors themselves noted), they've postulated that perhaps exercise is involved.

    This review actually agrees wholeheartedly with the findings of the study that I mentioned in the post and that authors noting that physical activity may be included as a means to explain their findings doesn't change the fact that proximity to fast food and supermarkets did indeed impact on weight status. What reading this review (and your comment) did convince me of is that your confirmation biases are much larger than mine given that the authors didn't reach the conclusions you've suggested and that your comment seemed frankly angry.

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  10. I have a question about this lack of linkage between exercise and weight: What about exercise when combined with caloric control? Do people who count calories AND get regular vigorous exercise lose/ manage their weight more successfully than people who only count calories and don't get much exercise? That's certainly been my own experience with weight loss -- weeks when I count calories but don't exercise much tend to be less successful than weeks where I both count calories and exercise -- but I realize that's extremely anecdotal, and I'm wondering if any research has been done on this.

    That being said: Even if it doesn't help with weight loss/ management, the other health benefits of exercise would seem to be strong enough that it's still worth encouraging it, and creating urban planning around it. I agree that we ought to be evidence- based about weight management, and if exercise doesn't really help with it that much we ought to be taking that into account -- but I'd hate to see us tell people "Don't bother to exercise" when there are so many other benefits from it.

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  11. Hi Greta,

    Absolutely, exercise has indeed been shown to help in the maintenance of weight.

    As well, and as regular readers of my blog are well aware, I'm a huge proponent of exercise for health's sake. That said I'm a huge opponent of public health interventions aimed at treating or preventing obesity with a singularly exercise based focus.

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  12. This seems like we're looking for another thing to blame obesity epidemic on. Instead, we should be looking at our own habits, behaviors and decisions we make.

    Let's not complicate it. It's all about the food intake and activity levels.

    Doesn't matter how close you are to food or the types of food, if someone wants to maintain a healthy lifestyle they will. But if someone wants to pig out, they will find a way to do that with a minimal of physical effort involved. Simple as that.

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