With a hit Broadway show and a highly praised performance in the Neil Simon movie Only When I Laugh, James Coco has never been bigger professionally. Yet, in a manner of speaking, these are lean times for the 52-year-old actor. In the past five years the 5'11" Coco has shed 110 pounds, dwindling to an almost sylphlike 195. No wonder he's smiling over the title of his latest musical—Little Me.

Coco's dramatic turnaround began in 1977. "I weighed 305 pounds," he recalls, "and I was desperate." Like most chronically obese people, Coco had tried every weight-loss scheme on the best-seller lists, including the Stillman water diet ("You have to know where every toilet is on 42nd Street"), the Atkins high-fat diet ("I had this awful taste in my mouth and was irritable all the time") and even something called the banana-and-cream diet ("If you eat just one food you're bound to lose weight—I gained 10 pounds"). In 1973, on the advice of his rotund pal Buddy Hackett, Coco traveled to Duke University's Dietary Rehabilitation Clinic in Durham, N.C., where he met Dr. Gerard Musante, a clinical psychologist. Four years later Musante opened his own center in Durham, called Structure House, and Coco enthusiastically enrolled. "This place is a godsend," he says today. "It was the last chance for me."

Coco's first stay at Structure House lasted four weeks. He lost 50 pounds. Since then he has been back at least 10 times to continue his therapy. Under the Structure House regimen, patients reduce through exercise and what Musante calls Structured Eating. That entails planning menus a week in advance, removing any threat of impulsiveness in a patient's diet. In addition, Musante and his staff of 12, including dietitians, psychiatric nurses, social workers, exercise experts and consulting physicians, hold group and individual therapy sessions. These are meant to help patients understand why they eat as they do. "Diets are deadly," claims Musante. "The emphasis has always been on getting down to some magic number on the scale. That's a myopic view. Being overweight is basically a psychological problem."

Coco agrees, and credits his own remarkable weight loss to psychotherapy at Structure House. "I had never had a head doctor before," he says. "I didn't think I needed one. But I've discovered a lot of things about myself." Among them were the reasons for his habitual gluttony. "They were every cliché you've ever heard," he says. "Frustration, not being content with the way my life was going, and a lot of childhood stuff." One of three children, Coco grew up in New York City in an Italian household where Sunday dinner "started at 2 in the afternoon and lasted until 10 in the evening." He began putting on weight when he was 9, but his parents, who were heavy themselves, never saw it as a problem. "I adored my parents," he says, "but [in therapy] I found myself saying I was angry at them. They made me finish everything on my plate because there were children starving. How about serving smaller portions?"

Coco's problems have occasionally been compounded by the demands of his career. In 1977 he starred in Albert Innaurato's play The Transfiguration of Benno Blimpie, about a 500-pound boy who eats himself to death. "I was padded, but I still had to eat onstage every night," he remembers. "They got me diet ice cream and low-cal this and that, but I realized the padding was getting a little tight. The play was highly successful," he says, "but the minute it closed, I went right back to Durham."

Whenever he visits Structure House, Coco entrusts himself completely to Musante. A trim 38-year-old, Musante says he can empathize with his patients because he struggled with obesity himself as a child. At 12, he was just under five feet tall but weighed 140 pounds. Not until 1972 was he able to get rid of his chubbiness by applying his nutritional theories to himself. A native New Yorker, Musante received his Ph.D. in clinical psychology from the University of Tennessee and his postdoctoral training at the Behavior Therapy Unit of the Temple University School of Medicine. He set up the Dietary Rehabilitation Clinic for Duke in 1973.

The menus at Structure House, devised by food director Jon Carmel, limit each patient's caloric intake to a meager 700 a day. Breakfast might be an egg-white omelet stuffed with mushrooms; lunch could be spinach soufflé or three ounces of spinach with egg, bacon bits, chicken and tuna. Dinner might consist of fish parmigiana or a small filet mignon with baked potato and salad, and fruit for dessert. While nothing is forbidden, bread and salt intake is restricted, and the caloric limit virtually precludes alcohol. "I wasn't aware you could eat that well on so few calories," one guest marveled recently. "I don't eat that much at home."

Coco is the first to admit, however, that dieting is never painless. "You'll be eating your supper there," he says, "and talking about enchiladas covered with chocolate." Once, after several weeks at Structure House, Coco felt an irresistible urge to splurge. With Musante's blessing, he and some friends ate their way through Durham, starting with a complete steak dinner and ending with candy and ice cream. "I gained eight pounds overnight," says Coco, "but I was never guilty about it. It was planned, and I was still dieting. It took me some time to take the weight off, but I never felt like bingeing again."

A typical day at Structure House begins at 7:30 a.m. with a five-minute warm-up and a one-mile walk. Patients are required to attend daily workshops on such subjects as eating in restaurants, nutrition and behavior modification, and to do exercises in the pool or ride stationary bikes. Coco takes part in most of the activities, but steadfastly refuses to join in the formal exercises—"I'm terrible at it," he says. Instead, he and the dieting pals he brings to Durham with him play cards, go to movies and walk around the city's 19 shopping centers.

The cost of treatment at Structure House is fairly modest. After a onetime $500 fee for new patients, a week's stay runs $190, which covers all meals and most activities, but not individual therapy ($50 an hour) or housing. Guests may choose between renting one of the 23 apartments Structure House owns or staying in a nearby motel. Newcomers must enroll for a minimum of four weeks, and many, like Coco, return for a few weeks every five or six months. "I feel healthy the minute I land at the airport," he says with a grin.

Back in New York, the actor is a conscientious calorie counter, limiting himself to 1,000 to 1,500 a day, and he helps keep trim by taking vigorous walks. Coco, who lives alone in a five-room apartment, does all his own cooking and entertains often. "I used to serve two different meals," he says, "one for me and one for my guests." Now Coco believes that low-calorie dishes don't have to be unappetizing. To prove it, he and a fellow Structure House alum, writer Marion Paone, have put together a collection of their own favorite menus. The dishes will be included along with an explanation of the Structure House philosophy in a book entitled If I Can, You Can, to be published by Bantam Books next year.

Still striving to reach his ultimate goal—170 pounds—Coco is optimistic about his eventual success. He keeps a photo from his Benno Blimpie days on a bedside table as a reminder to think thin. "If I get desperate," he points out, "I can always call Gerry Musante on the phone and say, 'Wait a minute. There's a problem here. We're having a pizza snit.' "