Monday, March 30, 2015

The case of South LA, Obesity and the Meaningless Law

You may have heard about the 'absolute failure' of a fast food zoning ban in South Los Angeles, California.  The ban on new, stand alone - very distinctly defined - fast food restaurants did not lead to a loss of weight for city residents, in fact, overweight/obese rates went UP after the law was 'on the books.'

Notably, the rates of overweight and obesity went up for ALL of Los Angeles and LA County. According to the study authors (Sturm and Hattori), South Los Angeles residents - ones whose behaviors and weights were captured in the California Health Interview Survey- had a higher rate of overweight obesity to begin with and their rates increased faster - or to a higher degree - than either the whole of Los Angeles city or LA County (their behaviors and weights were also assessed through the survey).

Whether or not a ban on new fast food restaurants - and it was not a total ban - was a good idea is for someone else to argue, but whether or not the study results are conclusive or even meaningful falls into the bailiwick of this (increasingly infrequent) blogger.  Yes, I end up giving an opinion about the law, I can't help myself sometimes.

This LA Times article provides a bit of information, though it does not describe the study methods. I accessed the journal article, the abstract is here. My main interest was in how the researchers went about collecting their data and answering their research questions. Sturm and Hattori (2015), used two main sources of data. They used establishment/restaurant permit records from the Department of Health and existing survey responses from a recurring/repeating survey - the California Health Interview Survey.  The survey responses (people) could be categorized by city, county, zipcode etc, so the researchers compared results between 3 groups, only one of which, South Los Angeles, was 'exposed' to the new regulation.

The regulation didn't really do much, I mean literally - it didn't do anything.  Fast Food Restaurants (FFR) still opened in Los Angeles, new business rose about 2% in all three locations. So from time 1 to time 2 there were actually MORE not less places for residents (or commuters?) to eat foods that were likely very high in calories. Between the time that the law went into effect and when the researchers evaluated the survey respondents FFR patronage frequency and their BMIs a second time, the environment did not change 'for the better'. There were not fewer FFR at time two, but would that have mattered? Research has shown that even sit down restaurants, fast casual or otherwise, serve foods that are calorically dense.  All away from home eating is associated with excess calorie consumption - so a law that prevents a certain sub category of FFR from adding more locations might make sense on its face, the result won't necessarily - or likely - be lower weights for the people who live in that area,

With an understanding of what did and didn't happen as a result of the law - i.e., FFR locations did not decrease or remain stable, they increased - how can one say that restricting FFRs does not lead to less FFR patronage or less calories consumed.  The law was flaccid at best - the first outcome - a decrease in number of restaurants or restaurant density did not happen. There was NO change in the obesogenic environment - people had as many if not more options for calorie dense food as before the law. So the answer to the first question: "Does a law restricting FFR lead to fewer FFR?" is no. Therefore, we can't answer anymore questions! But lets say the answer was yes, that five years later there were less restaurants in the area; the second question is: "Did the law lead to less consumption of fast food - or even better, much better, did it lead to few calories purchased/consumed?"

Now, is this the right policy?  Banning restaurants?  In some ways, it makes sense.  If there isn't a FFR on every corner, then FFRs become less popular, less 'normal.' And if FFRs were the only source of our passive overconsumption of calories, fewer of them might change our intake.  But they are not - there are plenty of sources of too many calories. The goal, in my opinion, should be to get existing establishment to reduce the amount of calories - across the board - that they put out for sale.

NB. Another possible 'confounder' for South LA is that people may not eat where they live - so capping the number of fast food restaurants does not change behavior if people are not eating where they live. 

Mom, you would be happy to know that I had three more paragraphs, but I realized I had already said what I needed to say so I deleted them.

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