Researchers say their work suggests that focusing on the sources of snack calories would address the differences between South Los Angeles and other parts of Los Angeles better than the current ban on new fast-food establishments.

"The ubiquitous availability of food can be overwhelming and stimulate hunger and cravings for food, regardless of whether an individual has a physiological need for nutrition," Cohen said. "Research has made it clear that frequency and saliency of food cues in the environment, the type of foods available, and the portion sizes served, are key issues that effective policies need to address."

One of the goals of the Los Angeles regulation is the creation of more sit-down restaurants, but in terms of diet, this is not necessarily an improvement, according to researchers.

"There is a misconception that sit-down restaurants provide 'healthier' food and are less likely to lead to obesity," Sturm says. "However, when we looked at some common offerings, an average lunch sandwich in a sit-down restaurant had more than the combined calories of three Big Mac hamburgers; many dinner choices have over 2,000 calories and cover the energy needs for a full day. And that does not even include possible appetizers or desserts."

The study also found that residents of South Los Angeles and those from wealthier areas reported eating out in restaurants at about the same frequency, although South Los Angeles residents are more likely to purchase items from a food cart or mobile vender and less likely to eat in a sit-down restaurant.

While residents of South Los Angeles and those from more-affluent areas seem to shop at similar types of stores, there was one dramatic difference -- many South Los Angeles residents walk or take public transit to the market, something seldom done in higher-income areas.

Source: RAND Corporation