Hamburger [© BananaStock\Jupiterimages](Hamburger [© BananaStock\Jupiterimages] )

"If you build it they will come" is a line from the movie Field of Dreams that has become a business motto of sorts. But in the fast food industry, it doesn’t necessarily hold true that if you sell it, they will buy.

“I’ve been watching this industry for nearly 30 years, and I’ve seen the restaurants put salad bars in, then take them out; add veggie burgers to the menu, then take them away,” says Harry Balzer of the market research firm NPD Group. “All these healthy things have been hot items, but they haven’t had legs.” His theory is that consumers aren’t seeing the immediate payback in terms of value and convenience that they crave.

“People have been trained to think that fast food equals junk," says Michael Jacobson of the Center for Science in the Public Interest. “So the restaurants are going to have to work hard to get health conscious people to eat there.”

Jacobson praises the strides that have been made—reduction or elimination of trans fats at some chains, additions of entrée salads, fruit and yogurt parfaits, and kids’ meals that come with carrot sticks and milk in place of fries and a soda.

But the best way to improve the nutritional quality of fast food menus is to be sneaky about it. Since most people who go in for a Big Mac, probably aren’t going to suddenly decide to order a grilled-chicken salad instead, the solution may not be adding new, healthier options, but taking the popular items and making them healthier.

“They could take the traditional offerings and make modest improvements—using 50 percent whole wheat buns, non-fat mayonnaise, better oils, a little more lettuce and less meat on a sandwich, lower sodium,” he says. “Over the years, those little changes—that most people wouldn’t even notice—could have a major impact on consumer health.”