The national restaurant chain Ruby Tuesday added a low-fat Blueberry D'Lite yogurt parfait to its menu more than a year ago to capitalize on the apparent growing appetite among consumers for healthful fare. The parfait joined more than 40 better-for-you offerings, along with listings of calorie and fat contents for everything on the menu. French fry portions were trimmed. Heavy advertising touted the chain's Smart Eating program.

But diners didn't bite. So Ruby Tuesday has eliminated the Blueberry D'Lite, along with several other healthful dishes ditched after a lengthy period of slumping sales at the chain. Calorie and fat information was dropped except on the healthful items that survived and were moved to the back of the menu.

Now the chain is aggressively promoting its biggest burgers, and in the last three months, burger sales are up 3 to 4 percent. It has also restored its larger portions of french fries and pasta.

Like many restaurant chains in the past two years, Ruby Tuesday has discovered that while customers say they want more nutritious choices, they rarely order them. As a result, fast food and casual dining chains -- which together account for three out of four U.S. restaurant visits -- are slowly going back to what they do best: indulging Americans' taste for high-calorie, high-fat fare.

"The gap between what [diners] say and what they do is just huge," said Denny Post, chief concept officer for Burger King. "Therein lies the challenge for business, because there is simply not enough behavior shift to build a business around."

Chains are not axing the healthful offerings altogether, because they serve a small niche market. But most companies are scaling back their promotion of good-for-you products, moving them to less prominent menu locations and, in some cases, cutting back on the number of more healthful choices.

"The first Ruby Tuesday opened in 1972. In those days, the number one item people ordered when they went out was a hamburger and french fries," said Richard Johnson, the chain's senior vice president. "Today, the number one items people order when they go out are a hamburger, french fries and chicken tenders."

Food researchers say people are slowly changing their eating habits, but mostly when they eat at home. In consumer surveys conducted by market-research firm Technomic Inc. of Chicago, "a clear majority said that they're less concerned and do not follow what they believe are good dietary habits when they're eating away from home," said company president Ron Paul.

While consumers who eat in fast-food restaurants are, in fact, more interested in nutritious fare than they used to be, "it's still less important than just about anything else," said Bob Sandelman, president of consumer research firm Sandelman & Associates.

The "availability of healthy and nutritious food" ranks 10th on a list of 12 dining attributes tracked by the firm, behind other desires such as speed and order accuracy.

Dan McDonald of Fredericksburg, a 30-year-old father of two, is concerned about the 30 pounds he has gained in the past five years, and he's trying to eat better at home. He and his wife are more mindful of nutrition when they feed their children, too. But when McDonald is running around Washington as a computer systems engineer, he eats fast food four times a week on his short lunch breaks -- typically a cheeseburger, fries and a soda.

"Usually if I'm going to get fast food, I'm going to get what I want, whether they have healthy options or not on the menu," he said, sitting at a window seat of a Burger King on K Street downtown. "My problem is I need to stay out of fast food places."

Experts in eating behavior say restaurant chains face several hurdles in pushing their more nutritious menu items. The biggest one is that people don't like to sacrifice at all on taste for the sake of eating something nutritious. Another is the higher prices that these items often carry, especially freshly prepared dishes such as salads and fruit. And finally, there is the lack of immediate gratification: When a customer orders something with a better nutritional profile, the benefit of that choice may or may not be noticed sometime in the future.

"You're not going to know if 'healthy' is going to be good for you until 40 years from now, when you're on your deathbed," said Harry Balzer, vice president of consulting firm NPD Group, which closely tracks people's eating habits. "The only thing you get immediately is time and money -- did I save time or did I save money."

Some restaurants have found that the best way to sell healthful items is to make them seem nutritious even if they're not. Fried white meat chicken strips have become popular on many menus and are big sellers, including atop salads, in keeping with the general perception that chicken is a more healthful alternative to beef. But at Wendy's, the Homestyle Chicken Strips Salad, eaten with one pack of ranch dressing, packs 670 calories and 45 grams of fat -- more than any hamburger or sandwich on the menu.

"With the salads, [restaurants] have doctored those products up," Sandelman said. "If people really knew, they would find out that the salads pack more fat and calories. That's why the key word in all this is perceived to be healthy."

One of Burger King's best product launches recently was its widely derided but oft-ordered Enormous Omelet breakfast sandwich, which was added to the menu in March. Chief concept officer Post is unapologetic about its 740 calories and 46 grams of fat.

"We found a gap in the market. We found people buying two breakfast sandwiches, so we saw the opportunity for one larger one," she said. "It's like brunch on a bun."

McDonald's has won much praise for adding healthful menu items, but only a tiny fraction of customers order them. The fast-food giant promotes the fact that it has sold 400 million premium salads since they were introduced more than two years ago, but that number is dwarfed by the chain's total customer count. McDonald's serves 23 million people a day in the United States alone, or roughly 16.8 billion people in the past two years -- meaning just 2.4 percent of customers have ordered salads since they were added to the menu.

"The most popular item on our menu continues to be the double cheeseburger, hands down," said company spokesman Bill Whitman. He acknowledges that the strong increases in sales at McDonald's in the past two years, which are frequently attributed to its healthier menu items, is actually the result of wider and higher-quality menu choices of all kinds, such as white meat chicken nuggets, as well as cleaner stores. "It's across the board," he said.

A Burger King restaurant will sell just four or five of the chain's better-for-you Veggie Burgers a day, but at least 300 to 500 of any other sandwich or burger on the menu, according to Post. The chain's highly promoted low-fat grilled chicken sandwiches, added to the menu last summer, disappeared in less than a year.

Applebee's International Inc. partnered with Weight Watchers in May of last year, adding branded, low-calorie items to its menu. "Initially, it was a broad-based effort," said John Cywinski, chief marketing officer for the chain. "We dedicated a good amount of our menu specifically to this, we advertised nationally on television, we supplemented that with some radio."

Now, the items have been moved to the back of the menu, and promotions are much more targeted, through Weight Watchers, for example, and in women's magazines, he said.

Restaurant chains say they can't eliminate healthier items altogether because "it's critical that you meet that need," Post said. In many cases, it's only to please one person in a group who might otherwise veto a visit to a fast-food outlet. "I will cast it in terms of the typical stereotype: The kids want to come and the dad wants to come and the mom wants a salad, so you better have a salad or they're going to go elsewhere. You can lose a large party."

The restaurant chains recognize that no matter what nutritious fare is on the menu, customers won't be flocking to the healthful items any time soon.

Cywinski echoes the sentiments of many other executives when he concedes that Applebee's Weight Watchers menu has hardly made a dent in the eating habits of regular customers. "It's glacial change," he said.

Signs advertise salads in the Cleveland Clinic McDonald's, where healthful foods were added.