If Elizabeth Taylor were to write a truthful autobiography, it surely would be one of Hollywood’s more entertaining real-life stories. Few celebrities have basked in the international spotlight for as long, with as much flair.

But apparently Taylor is not quite ready to tell that story yet.

Instead, she has written Elizabeth Takes Off — a lite-memoir and diet book that is alternately absorbing and dissatisfying — depending upon your reasons for reading it.

At its best, it is a somewhat inspiring story of a once-glamorous woman who appeared to have everything, and then ate her way to physical and mental destruction, before recovering in grand style.

Before launching into it, Taylor, 55, bluntly addresses her other addictions: pills and alcohol. But almost as quickly as she raises the issue, she cuts herself off, saying, “That’s another book.” Perhaps this means she’ll forgo the nifty 700-page tell-all her life story demands, choosing instead to chronicle her remaining battles in volume-ettes, as she does here.

Taylor’s 60-pound weight gain and loss is, by now, no secret. She has been candid about this struggle since emerging from the Betty Ford Center in early 1984. Startling before-and-after photos have accompanied many of her recent print and TV interviews, and are included in this book, too.

The weight problems began, she says, during her mid-30s, but really took off about 10 years later while she was on the Senate campaign trail with her seventh husband, John Warner. Initially, it was the erratic scheduling and greasy fast-food stops that added the weight, but then a combination of boredom and loss of self-esteem took over as Warner’s career gathered momentum, and hers remained stalled.

After Warner won the election, Taylor found herself alone most days and nights on their Virginia farm, while he toiled in Washington. She says her life had little purpose during this time, and accordingly her weight spiraled out of control.

To fight the boredom, she threw herself back into acting in 1981 — this time on Broadway in The Little Foxes. She forced off about 45 pounds for the show, but couldn’t maintain it. For most of the next three years she endured the yo- yo syndrome — all while denying the worsening of her drug and alcohol addiction. Although she does not directly say it, it is implied throughout the book that the stay at Betty Ford was the catalyst for coming clean in all respects.

From the classy tone, it seems she still holds Warner in high regard, despite their 1982 divorce. The same can be said of nearly all her ex-husbands, except the first — Nicky Hilton — whom she expectedly writes off as an immature, unreasonable run-around. The others — Michael Wilding, Mike Todd, Eddie Fisher and Richard Burton (twice) — are handled gracefully. She poignantly describes Todd and Burton as the men she loved most fully, but this admission comes as little surprise to anyone even remotely familiar with Taylor.

For the most part, the marriages, the movie studio anecdotes and childhood memories are included merely for background, and that’s what is so irritating about Elizabeth Takes Off. A flamboyant life such as hers cannot be glossed over in the scant 70 pages she accords here. She has moved in the innermost circles of Hollywood, politics, royalty and society for more than 40 years. Surely her observations must be more extensive than what she sets forth.

Taylor should have either written it — or not written it — but she shouldn’t have written it halfway.

Yes, she is blunt when describing the sight of her sagging, 180-plus-pound figure as she saw it for the first time in a full-length mirror, but the scenario is devoid of intensity. Surely, this must have been traumatic for her, but she barely delves into how she felt — only what she saw.

Elsewhere, there are gusts of brutal honesty in Elizabeth Takes Off, but when ghostwriter Jane Scovell steps in (as she does intermittently), the tone changes noticeably, and Taylor’s ethereal manner disappears. The star should have trusted herself to write it herself.

The second part of the book consists of imaginative menus, exercises and tips for healthy living. There is no startling information here either, nor is there a magic cure for obesity. Ultimately, she never really says exactly how she lost the weight — only that she felt “the click” — an inner signal of sorts that finally made her stick to a diet once and for all.

The attitude is upbeat and encouraging. “If I can do it, you can, too,” is Taylor’s recurring theme in these chapters, and somehow — despite her regal demeanor — the words seem genuine. Undoubtedly, many people will benefit from the motivation she provides. If that doesn’t work, another look at those then- and-now photos should do the trick.