A new study looks at whether banning or limited fast food restaurants would have any effect on people's body mass index.

happy meal from mcdonalds
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You know better than to go grocery shopping when you're starving. And similarly, it would seem to follow that you could reduce your waistline by distancing yourself from Taco Bell's siren drive-thru. But new research shows it doesn't really matter whether your backyard borders a Burger King or if you live miles from the nearest McDonald's—your proximity to unhealthy eats has little to do with BMI.

Indiana University researchers calculated more than one million study participants' body mass index, or BMI, using their height and weight when they'd visited a doctor or other healthcare provider. Then, the researchers analyzed how close participants live to chain fast-food restaurants, grocery stores, and other food spots, seeing just how many establishments lay within a three-mile radius of the participants' homes. And lastly, they checked how their BMIs fluctuated over a five-year period of time.

Here's what they discovered: whether a participant lived close to a fast-food joint at the start of the study—or gained easy access to a restaurant through a move or a new opening—didn't seem to tip his or her BMI one way or the other, they said.

But the researchers weren't conducting their study to find a secret to weight loss. Instead, they were trying to determine whether policies that prohibit fast-food restaurants, grocery stores, and supercenters—such as Target or Wal-Mart—hold any water. And they determined that, "public policies that are designed to reduce the number of fast-food restaurants and increase the number of supermarkets are unlikely to reduce obesity, although such policies may make it easier for people to access healthy foods," according to the study, published in the journal Health Affairs.

"Fast food is generally not good for you," said lead researcher Coady Wing, "and supermarkets do sell healthy food, but our results suggest blocking the opening of a new fast-food restaurant or subsidizing a [store] will do little to reduce obesity."