MONDAY, Jan. 21 (HealthDay News) -- It's not whether you eat out, it's where you choose to dine that affects your waistline, new research suggests.

People who live in neighborhoods with more fast-food restaurants are more likely to be obese than are people who live near more "full-service" restaurants, the study found.

"A lot of people have tried to understand why the obesity epidemic has come up, and some people hypothesize that eating out more might have something to do with it," said Dr. Virginia Chang, senior author of the study and assistant professor of medicine and sociology at the University of Pennsylvania School of Medicine. "Our findings suggest that eating out per se is not necessarily bad."

An obesity epidemic has indeed overtaken the United States, with some two-thirds of adults now considered overweight and about one-third categorized as obese.

Previous studies have implicated eating out as one factor contributing to the spread, and Americans are patronizing restaurants more than ever.

In 1940, Americans spent about 15 percent of their food dollars at restaurants, compared to more than 40 percent in 2005. And, in 2005, fast-food restaurants captured about 30 percent of the eating-out budget, versus only about 12 percent in 1960, the study authors said.

Probably not coincidentally, only about 7 percent of U.S. adults were obese in 1940.

"Eating in restaurants is a dangerous game," said Mireille Guiliano, author of French Women Don't Get Fat. "You have no control. You don't know what the chef put in, whether it's a lot of salt and way above the daily requirements. That's one challenge, but also the portions. In many, many restaurants, the portions are huge."

While previous researched had focused on state-level data, the new study, published in the February issue of the American Journal of Preventive Medicine, focuses more specifically on the county level.

The study authors looked at responses from more than 700,000 people participating in five years of an annual telephone survey of U.S. adults. Restaurant data came from the 2002 U.S. Economic Census.

Residents of areas with more fast-food restaurants and a higher ratio of fast-food to full-service restaurants were heavier than people from neighborhoods with more full-service restaurants.

"People who live in areas with more full-service restaurants do tend to be thinner," Chang said.

Restaurants were considered "fast food" if patrons paid before eating. In "full-service" establishments, patrons paid after eating.

The study pointed out that it's not clear if people actually consume fewer calories at full-service restaurants, or if individuals choose full-service restaurants because they offer healthier foods.

One study that compared "fast food" with food from full-service establishments found that meals from both contained similar amounts of total fat, but that full-service foods had lower amounts of saturated fats and higher levels of cholesterol and sodium.

For those fond of eating out, Guiliano recommends the "50 percent solution," meaning eat only half of what's on the plate. Or order two appetizers, share a dish and split dessert.

"You have to be a little bit savvy and know yourself and know how to plan," she said. "You shouldn't feel you should deprive yourself. You can have a little bit of everything. The French way is more about small portions and variety. Learn to not go overboard, because the price to pay is just too expensive."

More information

For more on healthy eating, visit the Harvard School of Public Health.

SOURCES: Virginia W. Chang, M.D., Ph.D., assistant professor, medicine and sociology, University of Pennsylvania School of Medicine, Philadelphia; Mireille Guiliano, author, French Women Don't Get Fat; February 2008 American Journal of Preventive Medicine

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