Along Allentown's S. Fourth Street, the smell of french fries is unmistakable. It saturates the air, saunters through open windows and sticks to your skin, your clothes, your hair.

On one long stretch, the fryers are working overtime at McDonald's, Popeyes Chicken, Pizza Hut, KFC, Burger King, Wendy's andDunkin' Donuts.

In this greasy mile, fast-food options may be packed more densely than anywhere else in Allentown, if not the Lehigh Valley. The bonanza comes not by culinary coincidence but through shrewd corporate marketing. And, medical experts say, it could have serious health consequences.

"It would take you a couple months to start at one end and eat your way through," said Peter Carr, who has lived in south Allentown for 60 years. "Things are changing, and the shame of it is, they aren't always changing for the better."

Two more fast-food chains — Sonic Drive-In and Checkers — plan to join the calorie-saturated strip, prompting the question: What is it about this two-lane road that makes restaurateurs think golden arches and plastic sporks.

The answer can be found in eight pages of market research prepared by real estate firm Colliers International for a hopeful Checkers franchisee who was debating where best to locate the burger joint.

Its maps and charts show that in the working-class neighborhoods of Mountainville and south Allentown, 100,000 people live within a 3-mile radius. People here tend not to be rich or college-educated. Households earn under the $50,000 national average. About half the people are minorities, mostly Hispanic. Slightly more than a third are high school graduates, while about 15 percent hold bachelor's degrees.

"It has ethnically diverse, densely populated people on a moderate income," said Derek Zerfass, a vice president for brokerage and retail at Colliers International.

In essence, the perfect fast-food demographic.

"Everyone's looking for the same thing, and when they find it, everyone takes it and runs with it," he said.

That explains why there isn't just one crowded McDonald's on the thoroughfare but a fast-food smorgasbord, Zerfass said.

On paper, the formula for fast-food success is straightforward.

But in reality, it clusters fast-food chains in poorer neighborhoods that have a higher proportion of minority residents, said Caitlin Eicher, a doctoral student at the Harvard School of Public Health who has researched neighborhood food environments.

For chains to succeed in a crowded marketplace, they need to attract customers who were raised on paper-wrapped burgers and buckets of fried chicken, she said. They need to appeal to people who don't have the time, money or knowledge to prepare nutritional dinners, or easy access to grocery stores, she said.

Fast food "offers the ability to feed a family for limited time and money," she said. But with that convenience come consequences.

In Pennsylvania, roughly 28 percent of adults are obese, according to a report by the Robert Wood Johnson Foundation and Trust for America's Health, a nonprofit that focuses on disease prevention.

The percentage is higher for minorities. More than 38 percent of blacks and 33 percent of Latinos are obese, compared with about 27 percent of whites in the state, according the 2010 study. One-third of adults near the poverty level are obese, while one-quarter of those making more than $50,000 are obese.

Eicher's research shows a link between a person's weight and food environment.

In other words, your neighborhood can affect your health, she said
read more