Here's what happened when Los Angeles banned new fast-food restaurants

Back in 2008, new LA zoning regulations restricted fast-food restaurants from opening in certain neighborhoods, and prohibited existing ones from expanding. It was touted as a public-health measure, aimed at curbing obesity rates in some of the city's poorest neighborhoods.

Now, four years of data shows those restrictions have not lowered obesity rates or changed the neighborhoods' eating habits, a new study from researchers at RAND finds.

Somewhat surprisingly, obesity rates actually grew faster in the areas with the fast-food restriction.

Obesity rates grew faster in areas with fast-food restrictions

The fast-food ordinance was passed unanimously by the Los Angeles City Council in 2008 and was enacted later that year. It covered regions home to about 700,000 people.

The measure came at a time when the proportion of obese and overweight people was much greater in South Los Angeles than in other areas of the city. But between 2008 and 2012, that gap grew.

Body mass index (a measure of body fat) went up in the area, and so did the percentage of people who were overweight or obese. In areas with the fast-food ban, the number of overweight or obese people jumped from 63 percent in 2007 to 75 percent in 2012. In the rest of the county, that increase was much smaller — just 57 percent to 58 percent.

The researchers did find one positive sign — soft drink consumption fell — but that happened across the whole city, not just in the areas covered by the ordinance.

The restriction didn't apply to many fast-food restaurants

Big chains with drive-thrus aren't necessarily watering holes for residents of a neighborhood. (Vivido/Flickr)

The researchers say that in large part, the problem with the ordinance is that it didn't target the right types of restaurants. The zoning regulation only applied to standalone restaurants, which the researchers argue left out many places dishing out unhealthy food, like convenience stores that sell chips and candy. From 2008 to 2012, 17 new fast-food restaurants were actually able to open in the area despite the ordinance, because they weren't standalone spots (rather, they were in places like strip malls).

The big, chain-style fast-food restaurants, meanwhile, might have been the wrong target. It's possible, the researchers think, the chains may be more popular with people passing through the neighborhoods (and not residents) because they have drive-thrus and are often located on major roads.

The numbers also might not necessarily come down quickly with any policy, because people form their eating habits over life and could be slow to change them. There isn't any one way to drastically reduce obesity, the researchers say, but for cities with goals similar to Los Angeles', policies should take smaller food markets and other types of restaurants into consideration.

WATCH: 'What's wrong with food in America'

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