Carole Bayer Sager looks like a butterfly, tiny and fragile, with elaborate makeup around her eyes like delicate wings. From the eyes, the bold black-and-white striped jacket, the leather pants with matching boots, the brooch of Mickey Mouse wearing crucifix earrings, it is clear that she is a butterfly from an exotic and fanciful place: Hollywood.

But Sager, 38, is not just from Hollywood; she is from Show Business. If you haven't heard of her, you have heard her work. She has written the words to a good many songs, starting with a "A Groovy Kind of Love" when she was in high school. The hits have come regularly since then (1960), including Carly Simon's "Nobody Does It Better" (from "The Spy Who Loved Me"), Neil Diamond's "Heartlight," Dolly Parton's "Heartbreaker," Aretha Franklin's "Break It to Me Gently," Melissa Manchester's "Midnight Blue" and Roberta Flack's "Making Love."

She is married to composer Burt Bacharach, and together they have written a variety of songs including the 1981 Academy Award winner, "Arthur's Theme (Best That You Can Do)." The two also perform in concert, as they are doing tonight at the White House dinner for the prince and princess of Liechtenstein, and later this week at a benefit. She also lived for several years with composer Marvin Hamlisch, with whom she wrote the songs for the musical "They're Playing Our Song" in 1979.

Now Sager has written a novel, "Extravagant Gestures." It is about a well-known writer who is an expert on the mother-daughter relationship, her eccentric and difficult mother, her best friend, who is a famous movie star, and her lover, a popular psychologist who has written a bestselling book. They live in New York and fly -- first class -- to other places, ride in limousines, write with Cartier pens and wear cashmere. The writer also is obsessed with her weight, and has an eating disorder: she secretly chews her food and then spits it into a paper cup.

Sager is part of a phenomenon of modern popular culture: the person who segues without pause from one media outlet to another, like the movie star who writes an autobiography, the hairdresser who produces a movie, the writer who writes a novel and then a screenplay. Sager, in addition to her songwriting and concert performing and the novel, has recorded three albums as a singer and has recently become a record producer.

Sager said she decided to write a novel because she felt "constricted" by the 36 bars of a song's lyrics, having to make things rhyme and so forth. She started out to write a screenplay, but that was constricting too. "You make your own form in a novel," she says. "I didn't even have chapters. I let them the publishers put the chapters in."

It took her a year to write and then rewrite the book. Compared with some writers that may not seem like much, but when you consider that it takes her about two hours to write the lyrics of a song, and that she can earn $10,000 for doing it, a year is quite a long time. And she is glad she did it. "It was never real painful," she says. "I never had any of that angst people talk about."

Although the story in "Extravagant Gestures" certainly clips along, attention to small details does not seem to have been a great concern. The first sentence describes a "fiftyish-year-old polyester-sized woman," for example, and an 18-month-old child is said to weigh 53 pounds. The book is sprinkled liberally with exclamation points.

"My goal was to write something from me, that turned me on, that told a story. And I didn't even know what that story was until I was well into writing it," she said. "It was a growth experience for me. As a collaborative being, a person who has spent 20 years writing lyrics for composers, this was the first time I felt I could do something alone."

If writing the novel wasn't painful, neither was finding a publisher. Having already shown her work to Esther Margolis, president of New Market Books, while the two were both staying at a health spa (Erica Jong, who contributed a blurb for the book jacket, was another guest), Sager called up a man she had seen on a public television program about writers.

"I was so naive about publishing I thought you could just hire an editor, the way you hire an agent," she said.

The man was Robert A. Gottlieb, who is editor in chief of Alfred A. Knopf Inc. He agreed to read the 40 pages she had written to determine "if I could write." The verdict came back that she could, and Gottlieb continued to encourage her. But in the end, she said, he didn't feel it was "right" for Knopf.

"He said my writing style was a little bit close to Nora Ephron, and they have a very close relationship. I don't think I write like Nora. I think I'm funny, and I think there's a lot of humor in my book, but there is also a tear." Actually, she said, "I don't read enough to know who I write like."

She chose Arbor House, because, she said, she adored the editor she worked with, John Dobbs. She willingly rewrote the manuscript. And then the sad truth of the book publishing business came home to her: It's just like show business. Only there's less money involved.

"I was stunned. Stunned," she says. "I thought one of the byproducts I would reap from having written this book is that I would be free of the hype and razzmatazz of the music and film worlds. I immediately rethought that when I was marched into the American Booksellers convention in San Francisco, which makes a record convention look like a small breakfast party."

Then there was the question of her book party. Elizabeth Taylor, who recently became a good friend, agreed to host it. Sager wanted to have it at Tiffany's in Los Angeles, because the color of Tiffany's boxes is the same blue as the jacket of her book. The store agreed, and even sent out the invitations.

"They told Arbor House the party for 200 would cost $7,000. And Arbor House was stunned. They told me perhaps they'd take a few ads away from me. Oh my God! I thought they were going to take away my ad in The New York Times. Your raison d'e tre for writing a book is to see your ad in The New York Times and now they're going to take that away for an hors d'oeuvre!"

Sager ended up paying for part of the party. Then came the publicity tour, 10 days of interviews in different cities. "Erica Jong's friend says that a promotion tour is your punishment for having written a beautiful book. I love that line. Lynn Nesbit Sager's agent keeps telling me that I am so fortunate, that this is a very nice gesture for a first novelist. But for me, who hates flying . . . And I call myself a feminist, but I hate being away from Burt. And I hate getting up early in the morning."

She travels with her secretary and has picked up some of the travel costs. "I mean, I don't want to stay in a Holiday Inn." (In Washington, she stayed at the Madison.) "I said to Burt, 'If all this continues on schedule, this book could be a best seller and I'll be out $100,000.' "

But she had fun writing it, and she may even write another. Or, emboldened by her literary experience, she may attempt the book for a musical comedy, writing the songs with Bacharach. She already has an idea for that: "It's about someone writing a book," she says.