The Incomparable Hildegarde is 72 and dress size 12 - expensive dress size 12. She abhors "those three white things - refined sugars, flour and salt." She can't stand yogurt, either. She mixes her own breakfast cereal, travels with organic foods and honey, salt substitute and peppermill, Mountain Valley water and vitamins. She believes that, "if you don't dominate Mother Nature, she'll dominate you. She says, "You have to take care of your health, you have to take care of your looks, you have to watch your weight.

"On, the calories, on the carbohydrates," she moans, biting into a Dolley Madison cinnamon roll. "I don't eat this kind of thing - it's like cheating at solitaire."

Hildegarde, nee Hildegarde Loretta Sell, has been in show business for 52 years.She became, if not a star of the first magnitude, a personality of the first class. She started as an accompanist in vaudeville; at her height (and that of the fine hotel clubs) she spent six months in residence at the [LINE ILLEGIBLE] Hotel. She played the St. Regis' [WORD ILLEGIBLE] the Statler the Shoreham. She became 'Incomparable" thanks to her first press agent and columnist Walter Winchell, a story she tells in her show. She still works about two-thirds of every year, including this week of two-shwos-a-night at the Waaay Off Broadway cabaret. She intends to keep on performing for another decade.

"This is my lifestyle, my duty, my ledication. I say 'Lord, 'd like to keep doing this till I'm 80,' because that's when Maurice Chevalier and Sophie Tucker left this planet to fulfil their destinies."

Hildegarde has never been one to make a fuss about her age. Fifteen years ago she published a book called "Over 50 - So What?" detailing her health and beauty regimes. Her special causes are the elderly, "the really old who are alone and abandoned," and the war veterans. She often dedicates songs to the elderly during her performances.

Still, she is inordinately careful about her appearance, and speaks of the "discipline" required to keep it up as a kind of religious duty. Her makeup is a little heavy for daytime (she has been on a television talk show) and her [WORD ILLEGIBLE] Channing [WORD ILLEGIBLE] say wig doesn't suit her perfectly, but tonight on stage she will be beautiful, newly coiffed and in one of her famous evening gowns.

She is planning to paray her fame and perservation into a personalized line of cosmetics "for women over 49" - [WORD ILLEGIBLE] Comsmetics by Hildegarde. She will do the television advertisomons that kick off the mail-order sales. Eventually, the cosmetics will be sold through better department stores, etc. And she may follow that with a few selected health foods.

"You mustn't get too diversified. I've always concentrated on my career." So even as she searches for a couple of "angels" to help inance the cosmetics business, she is talking to producers about a one-woman Broadway show and working on the first chapters of a second book.

Her life is all music; it always was. "When I was 18 months old in my mother's arms, she took me to hear an opera. When she brought me home, I was humming the aria."

She's been traveling since 1926. She had some small romances - "In vaudevillo we always fell in ove with the leading man, just like they do in Hollywood [WORD ILLEGIBLE] three really big ones: But she never married, and eventually those man died. I'd say 'Hello' today and 'Goodbye' tomorrow," she says, looking away a little. "In retrospect . . . it would have been nice to be happily married if I could have had a musical career. I have to express myself through music. And being a religious person, I believe that if God had wanted me to have a husband and a family, I would have."

Nowdays she travels alone, except for her musical director and 10 pieces of luggage (it used to be two dozen). When her personal maid died, Hildegarde began doing for herself. She lives alone in a New York apartment stuffed with paintings, ranging from four of her own works, done at age 18, to some masters - Monet, Picasso, Renoir. One sister lives in Florida, the other in Texas. Even her lontime manager (and sometimes accused Svengali) Anna Sosenko, is gone. But she does not complain of loneliness.

"(My career) is blooming," she says strongly. "I'm not just a stand-up singer. I'm a performer. I have to do what I'm doing, make people happy, give them a lift. That's what God wants."

She looks a little like Arlene Francis Rpt. more risque - you wouldn't catch Arlene Francis in a pull-down [WORD ILLEGIBLE] 20s cloche spitting out a mouthful of dyed boa feathers.

Hildegarde's opening performance last night at the Waaay Off Broadway cabaret was not a sell-out - not even close. But the grapevine should triple business.

Her seeming throwaway one-liners extremely funny and delivered with just the right twist: her announced "jokes" are proper groaners.

She makes good use of her age, 72: it's the source of most of the humor, but she never makes it an excuse. She - or her musical director. Charles Creasy - has chosen her material with an eye toward the latitude of "talking" some lines, but when she cuts loose on "Thoroughly Modern Millie" (reworked as "Thoroughly Modern Hildy"), it's clear she knows what she's saving her voice for.