A law limiting fast-food outlets in southern Los Angeles has failed to curb obesity rates, a new study shows. Above, a McDouble burger is pictured at a McDonald's restaurant in the Fillmore District of San Francisco, on Jan. 30, 2013. Reuters/Robert Galbraith

A 2008 law to prevent new fast-food outlets from opening or expanding in a 32-square-mile area in an impoverished district of Los Angeles has accomplished nothing in the way of cutting obesity rates or leading to more healthful diets, a study by the RAND Corp. has shown. “The South Los Angeles fast-food ban may have symbolic value, but it has had no measurable impact in improving diets or reducing obesity,” Roland Sturm, a senior economist at RAND who led the effort, said in a statement releasing the results of the study, which was published in the journal Social Science & Medicine.

The law passed in 2008 banned any new "standalone fast-food restaurant" from opening or expanding in southern Los Angeles areas with a total of about 700,000 residents. In their research, the authors of the study examined permits for food outlets issued by the Los Angeles County Department of Health and looked at surveys of local eating habits and health issues. They found that from 2007 to 2012 rates of being obese or overweight increased the fastest in the areas with the fast-food ban, with average weight-to-height ratios increasing and an overall higher proportion of people who were overweight or obese.

New food outlets, mainly smaller ones that were not part of large chain companies, have been approved since the law's passage, but the researchers did not find any proof that the law changed what those restaurants were offering to customers. The researchers did find, however, that consumption of soft drinks decreased throughout the Los Angeles area since 2007.

Councilman Bernard C. Parks, who co-wrote the zoning restriction, defended the law, saying it was an important first step. "We never believed it was going to be an overnight situation where all of a sudden the community was going to be healthy," he told the Los Angeles Times.