At Food For Thought, affectionately called Thought For Food, the customers and even the food itself sometimes seem irrelevant. Here is a family of free-spirited, endearingly eccentric characters who happen to work in a neighborhood restaurant, one with a certain comfortingly raffish suggestion of earlier days around Dupont Circle, days before Haagen-Dazs and Le Sorbet, before bookstores with cafes in the back and Walkman-wired browsers in the front, before newstands selling croissants and 75-cent chocolate chip cookies.

At Food For Thought, the black vinyl booth seats sag, the wooden tables are scratched and unshaded by hanging plants, the live entertainment includes more folk singers than New Wavers, the jukebox may have Luciano Pavarotti and Louis Armstrong but it also has the Rolling Stones, and the kitchen bookshelf holds Tofu Goes West and the George Bernard Shaw Vegetarian Cookbook as well as The Joy of Cooking.

Perhaps the serendipitous essence of the place is best captured on the bulletin board, a kind of journal of alternative life styles and political activism.

It advertises gay group houses, organic farms, peace marches and ERA rallies, astrological counseling, secondhand massage tables, job openings at the Women's Community Bakery and, recently, a quest for a date for the Judy Collins concert with a "visiting intern, vegetarian, cyclist, runner, conservationist, 20s, environmentalist, nonsmoker, nonchauvinist, pro-ERA" male ("Ticket and transportation provided, no strings attached, simply seeking company; If omnivorous I can live with that"). Even the pay phone has a message, a bumper sticker that reads: "Love Animals, Don't Eat Them--Fruitarian Network."

There is an air of festivity about this Connecticut Avenue restaurant, where the hosts, cooks, bartenders and waiters and waitresses--known as "waitrons" by the zealously nonsexist staff--include aspiring actors, poets, rock stars and the ethereal Deardra Hingle, whose former jobs include go-go dancer, cab driver, telephone operator and prison guard, and who waits on tables downstairs in cheerful multicolored costumes of gauze and cotton and offers foot massage upstairs.

The atmosphere is obviously congenial to the owner, Bobby Ferrando, a man who fantasized about driving a motorcycle through the restaurant and finally lived his dream at a staff party.

You may see waitresses jitterbugging in the aisles when Buddy Holly comes on the jukebox, and a meeting of old friends is marked not by a decorous peck on the cheek but with a bear hug. Callers sometimes hear the bartender, David, who will not identify himself further, announce, "Nutrition for Cognizance," which he views as a loose translation of the restaurant's name.

Underneath all this hilarity, in the basement where the food is cooked, is the unmistakably exuberant Jake Harbin, a suntanned blond woman whose right calf is tattooed with a butterfly, and who is a former Montgomery County schoolteacher who once wanted to win fame as an actress and now wants to be known for her sauces.

"I love making sauces," she said. "A sauce to really do something to your chicken, to wake it up; a sauce nobody else makes."

Among the tables goes gangly, ponytailed Gordon Hartman, tall and towering, a botanist, butterfly collector and 1960s activist who, ever since the restaurant opened nine years ago, has served food and philosophy, leavened with his wry observations of the changing Dupont Circle social scene.

"It's a time warp here," he says. "It's still 1968." Hartman, at 39 the oldest worker, says this ambiance keeps out a certain group that might be considered less than desirable at this restaurant: "Fortunately, we don't get too many of the quiche-and-kir crowd."

With characteristic attention to detail, he recalled the time, four years ago, he waited on Gloria Steinem. "It was unremarkable," he said. "She had a small salad, a pot of tea and tipped adequately."

Food For Thought's fare includes hamburgers, hot dogs (nitrite-free) and chicken and fish specials as well as such items as sprout and fruit and nut salads and a drink called ginseng rush. Diners who mistakenly expect strict adherence to vegetarian principles are shocked to discover that at least half the staff smokes cigarettes, drinks Cokes and eats meat. In these nutritionally obsessive times, Hartman's own philosophy on food is refreshingly tolerant: "Eat whatever you think you need, and don't worry about it."

Ferrando, the 38-year-old owner, is a man with a story to tell, of the transformation of his own nutritional principles and of the arduous and sometimes zany struggle of the restaurant based on those principles to survive and to suceed.

Ferrando is a confessed and reformed junk food addict who used to breakfast on six slices of white bread slathered with butter and washed down with sugar-laden coffee. The turning point came one night when, almost unconscious with stomach pain, he staggered to the hospital emergency room where doctors saw him as a case of acute indigestion and he saw the light of dietary righteousness.

"No more cellulose milkshakes at McDonald's," he said. That was in the late '60s, when Ferrando was working in his father's catering business, furnishing decorated ham and turkey platters and such to Chevy Chase cocktail parties.

"Empty food, empty people," he said the other day, seated in his comfortably shabby office above the restaurant at a desk heaped with boxes of Celestial Seasonings tea and strewn with samples of whole wheat pita bread.

"I wanted a place that was real, without pretenses." he said, explaining the origins of his establishment. "I wanted to serve good food." With financial help from a man who wanted to quit the business world and become a bar owner, he bought a greasy spoon that was failing miserably, and in its place, at 1738 Connecticut Ave. NW, on Feb. 6, 1973, he opened Food For Thought.

The name of the restaurant was a nocturnal inspiration. "I woke up at 4 in the morning and there it was." The first cook was Diane, who was then also his wife.

"She was cooking the same stuff as we were eating at home. She just upped it from four to 100." The restaurant was an initial success, with crowds that frequently reached its capacity of 99 persons, feasting each night on such low-priced specialties as 90-cent natural hamburgers, 50-cent peanut butter and jelly sandwiches, $1.50 Greek salads and 30-cent slices of organic gingerbread.

Ferrando, a gentle person, wanted his restaurant run communally, with all the help sharing in decisions. "I didn't want to push people around," he said.

So disaster came to Food For Thought. One of the principal decisions made by the staff, most of them in their early 20s, was to play their own music tapes at high volume, blasting defenseless diners with rock and roll.

"Ninety, 100 decibels wasn't too loud," Ferrando recalled. "It attracted people who wanted to distort their minds and deal drugs. All the scum of Connecticut Avenue came here. The good people were chased out." Nights at Food For Thought ended frequently in fights.

"I didn't consider it a good night unless my life had been threatened at least once," said Hartman, the waiter who has seen it all.

Then the first summer came; and the air conditioner, a vintage 1933, 20-horsepower Westinghouse, surrendered to time and temperature and exploded and burned. Business dropped, Ferrando finally fixed it and the customers returned, but the rowdy reign of rock 'n' roll continued.

And so three years passed, during which Food For Thought lost money steadily and Ferrando grew discouraged and even thought of selling.

Finally one day, a woman in her 50s named Edie, an upright and dignified person who had remained a faithful customer through it all, saved Food For Thought. She did it by going to Ferrando and telling him that what the place needed was a hostess, and that the hostess it needed was her. She was right.

Presiding in her floor-length gowns and fine jewelry over one of the more raucous places in town, said Ferrando, "she was shocking,"

"The average customer back then came in expecting to check out who was at the bar and deal some drugs. And there would be Edie in a dress saying, 'How many? May I seat you?' They'd walk right out again."

Milestones were marked. "Pita bread came in," Ferrando said. "The tape system went. We got a jukebox." Edie left, and now the hostesses are called hosts and include 23-year-old Jane Lincoln, who came to Food For Thought a year ago and was immediately hired by the head dishwasher, who was impressed not so much by Lincoln's kitchen skills as by her name and astrological sign. "When I told her my name was Jane and I was a Leo, she said, 'You're hired.' "

And so the restaurant prospered. Business picked up, and in the last four years Food For Thought has made a profit each year, with new and desirable customers replacing those who had been the despair of Ferrando.

Gone was the family that refused to use forks and instead ate their salad with their fingers and flung the lettuce about when helpful waiters offered utensils. Gone, too, was Mrs. Vicious, so named by the staff for her habit of ordering a cup of coffee and then loudly upbraiding it; The Fly, a man who claimed he was a fly with a broken wing; The White Hat Tip Snatcher, who stole the workers' tips; and The General, who claimed to be the commander of a starship.

Food For Thought draws other kinds. Responses to a recent restaurant survey asking diners who they are included film maker, blue-collar worker, artist, law student, feminist, gay rights activist, pacifist, vegetarian, Frisbee player, and "nice person."

Seven days a week they come to Food For Thought for lunch and dinner and, in the written words of one of those who responded to the survey, to "figure out the history, character and quirks of everyone who works here."

For this, it might be helpful to start by reading the entries in the spiral notebook that hangs on a wall at the back. Called "Rona," it is a daily staff log of life at Food For Thought.

Recent entries: "Dearest Annie, Did I tell you how much I loved your walnut cheese loaf?--Geri;" "Ruth, Was it you who put so much oil in the wok? I know you was in the dulldrums last nite so don't take this little note personally. OK. Sweetie;" "Let Me Guess, We made cement for an outdoor patio but decided to make our quiche crusts out of it instead . . . Who is responsible for zucchini Q?"

And there was this entry, the extravagant joy of which seemed expressive of Food For Thought: "Whoever made the tomato bulghur soup, I offer you my kudos, accolades and general supreme compliments! Signed: Four Bowls and Still Eating."