Quick – give me three words you never would expect to hear together.

Sox win series? Comfortable stiletto heels? Smart reality television?

How about “natural fast food”?

Well, the first may never happen again. The next two may never happen, period. But the latter is here to stay, thanks to O’Naturals, a chain of quick-serve restaurants that began in Falmouth and since has expanded to Portland and Massachusetts.

Good things happen when you have a yogurt magnate who wants to feed his kids something other than burgers and fries on the way home from a soccer game.

In 1997, Gary Hirshberg, founder of Stonyfield Farm in Vermont, brought together marketing wizard Mac McCabe of Falmouth and Pam Solo, president of the Institute for Civil Society, to research the market for a fast, family-friendly restaurant that served natural, wholesome food.

McCabe, who had worked for years in the natural foods industry, knew others had tried and failed. But he also knew few people were willing to commit to the concept 100 percent. He needed only look as far as the soda fountain.

“Diet soda, we perceived that as being the linchpin,” McCabe said. “Every restaurant, from McDonald’s to Lutece, serves some sort of diet soda product – except for O’Naturals.”

The coffee is organic. The soda is naturally flavored. The meats that aren’t organic are either wild, free-range or hormone- and antibiotic-free. And you won’t find anything fried on the menu.

But this isn’t some sprouts-and-tofu operation (although both can be found on the menu). Sure, you can get vegan Caesar dressing, soy “chicken” and natural fountain soda. But you also can order roast beef, rosemary onions and Swiss on homemade flatbread. Or spicy Asian noodles with snap peas and zucchini. Or prairie-raised bison meatloaf.

“Frankly, if it doesn’t taste good, what good is it?” McCabe asked in a recent phone interview. He was calling from his car, en route from the newest O’Naturals in Somerville, Mass., to Maine.

Tasting good is only part of the equation, however. At the Old Port location, small, wooden tags let diners know how much thought went into every aspect of the restaurant’s design – from the natural linoleum on the bathroom floors to the coating on the soaring plate-glass windows which helps to reduce heat gain, saving energy. The tables are made of maple from certified sustainable forests. And during a recent visit, the cooks were singing in the kitchen, which seemed natural enough.

At a neighboring table, a mother and her young son had a conversation in French while she dug into a salad and he took spoonfuls of pasta shells and red sauce. As they prepared to leave, a tall, slender woman in a velour sweat suit sat down with a flatbread sandwich.

“I look for a healthy approach and usually don’t have a lot of extra time,” said Erica Napuli, 29, of South Portland. Napuli works nearby as a personal trainer and she usually packs her own lunch, but she comes to O’Naturals about once every two weeks.

“It’s a lighter, healthier approach than some of the other options,” she said. “The only thing I see as an obstacle, and there’s no way to avoid this, but the cost is a little higher. But if people are really health-conscious, they’re willing to pay a little extra for healthy foods.”

Before O’Naturals opened in 2001, its founders conducted extensive research with families who already bought natural foods at the supermarket. They found an interesting contradiction – these families spent extra money to prepare food at home, but they also were heavy fast-food eaters.

“Huh? That didn’t make sense,” McCabe said. “Between violin lessons and soccer practice, they’re making these decisions: Is Subway really OK? Is Wendy’s better than McDonald’s? Or should we just get Thai takeout?”

The demographic wasn’t necessarily more affluent, but it was more educated, and these families were willing to spend more money for organic and natural food. An adult meal at O’Naturals, with a beverage, costs about $7 per person, a bit higher than the average burger joint. But this isn’t your average burger joint.

It’s more of an experience – especially for parents who want good food but don’t want to feel ostracized when their kids start to scream or throw napkins at the people two tables over. There’s a play area in each shop, a full children’s menu, and no nagging guilt about fried food.

But it’s not just about the food.

“This is our belief system,” McCabe said. “A lot of people, especially diet-conscious people, think this is about food. … It’s about what we’re doing to the earth. Diet means different things to different people – low-fat, low-this, low-carb, low-sugar, low-salt. We’re just really talking about clean food. Clean food is what we ingest. Clean food is what we take out of the ground.”