The Fountain of Youth or Medical Baloney?

It's nearly impossible, even now, to see Suzanne Somers and not be reminded of her trademark laugh.

Her Chrissy Snow character was one-third of the "Three's Company" trio, which dominated prime time television in the 1970s and '80s. Sweet but simple, Chrissy became an enduring television icon.

But playing that role would not be the last chapter in Suzanne Somers' story.

Watch the story tonight on "Nightline" at 11:35 p.m. ET

She is now a best-selling fitness and nutrition author with more than 10 million books in print.

Suzanne SomersPlay

"The theory behind anti-aging is keeping your insides young -- keeping your body strong," Somers said.

Now 61 years old, Somers brought "Nightline" along to visit one of the doctors she champions in her latest book, "Breakthrough." She is the self-styled face of what she describes as the visionary field of anti-aging medicine.

"I'm probably more involved with doctors than the average person," Somers said. "I don't think we practice health care in this country. I think we practice disease care."

Central to her message is the use of unproven, potentially dangerous hormonal therapies, making Somers as controversial as she is successful.

"I'm probably the happiest I've ever been in my whole life," she said. "And the most content. The most fulfilled. The most satisfied. Doing what I love."

A Bumpy Road to a Happy Place

She played Chrissy Snow for six years until a contract dispute forced her out of "Three's Company." She said the show's producers literally banished her from contact with the rest of the cast.

"They forced me to finish out my contract but relegated me to one minute at the end of the show," she remembered. "I was not allowed to interact with anybody else in the cast. An armed guard would meet me at the back door of the studio and walk me in so that I wasn't able to interact with anybody, and that was traumatic."

But her life after so much success in a short amount of time was not one Somers had hoped for.

"I couldn't get a job anywhere," she said. "I couldn't get an interview anywhere. I was considered trouble in the industry. And one day,I thought, 'Why don't I focus on what I do have?' And I thought, 'What do I have?' I have enormous visibility. Everybody in this country knows my name. That's worth something."

Somers enjoyed huge success using her name to sell a long list of lifestyle and fitness products, including the iconic ThighMaster.

In middle age and still a fixture in the fitness industry, Somers became focused on how aging was affecting her body. She was dissatisfied with what mainstream medicine offered.

"I just looked around, and I saw something happening," she recalled. "I saw that from the time people reached middle age, they start on pharmaceutical drugs. [Do] we really need a prescription drug for every single ailment?"

Anti-Aging's 'Bad Rap'

She believes she has found a better solution. In her new book, Somers promotes untested hormonal treatments as cures for the effects of aging. These claims about hormone replacement, repeated in millions of printed pages, have made her a lightning rod for criticism.

"Anti-aging gets such a bad rap. It sounds like it's a bunch of quacks," she said. "What it really is are some of the brilliant minds in this country have stepped back and said, 'There has got to be a better way.'"

Somers admits she has no medical training and is not a scientist, but she also insists that she knows what she is talking about.

"I understand science," she said. "I don't know why. In school I always got A's in science. I always knew how to connect the dots. And I didn't want to write just another hormone book. This one takes you into a new realm of wellness."

Much of what Somers recommends is not in dispute, that eating right and exercising will improve your health. But the controversial centerpiece of her anti aging regimen is a recommendation for the ongoing use of "bio-identical" hormones.

"We do replace our hormones with bio-identical hormones to optimal levels, as you know," she explained while at one of her doctor's appointments.

She claims the use of these hormones, which are extracted from natural ingredients -- like yams -- will prevent deterioration from aging without the risks associated with synthetic hormones approved by the U.S. Food and Drug Administration.

"I don't think that we have to degrade as we age," she said. "We get older. And it's not about the exterior. It's about keeping the interior of you young. Youthful organs. A youthful, internal system, which manifests on the outside and makes you look better."

Common Sense or Nonsense?

Much of the medical community is outraged by Somers' claims, noting the hormones she promotes carry the same active ingredients and the same or even more risk than their counterparts that the FDA monitors and approves.

Hormone treatments do have proven benefits, which include improving bone density and easing the symptoms of menopause, but Somers said the potential is far greater. Though none of her claims are backed by rigorous scientific studies, she firmly insists that hearing, memory and vision loss, and more, can all be prevented or reversed by hormone replacements.

"I don't think we have to get Alzheimer's because we age," she said. "I don't think we have to have heart disease because we age."

The pitch is hard to resist. She also credits hormone replacement therapy for a robust sex life.

"I can't tell you what this has done to our already great marriage," she said. "You know, the kids are gone now and we have the house to ourselves, and it's nice."

Somers' success in reaching a large audience with this message had drawn complaints from the medical community.

"The public loves snake oil salesman," said Wulf Utian, the executive director of the North American Menopause Society. He said her work in promoting bio-identical hormones could do serious harm.

"It's been in our tradition since the time of the Wild, Wild, west," he said. The wagon rolls into town, the snake oil salesman gets out. He makes a great play. Everybody buys. He gets out of town as quick as he can. I think this is the same story all over again."

"The promise she makes is actually dangerous because she is saying the use of [bio-identical hormones] are safe and do not carry the side effects," he continued. "So example, if the estrogen is taken the way she suggests it should be taken, then it will have the benefit on the bone and the skin and so forth, but it won't carry an increase risk of cancer or blood clots or heart attack or strokes. That is absolute nonsense."

But Somers said, "[I] feel in 10 or 20 years, everyone will understand this as a given," adding, "I've been on hormone replacement now for 13 years. I chose to treat my cancer ... [even though] doctors told me I would probably die because I refused chemotherapy."

Somers underwent surgery and radiation to treat her breast cancer eight years ago but declined chemotherapy in favor of a homeopathic treatment, a decision she credits for keeping her cancer-free.

This approach, the use of her own body as a test case for the treatments she advocates, has her critics worrying that good science is being muddied by her fame.

"In good medicine, the products that we use and recommend to individuals ... need to go through good testing," said Utian. "And the only organization that can do that and really covers that is the FDA. Without the FDA, we would have 1,000 of these kinds of books and 20,000 of these products for sale, I promise you."

"His job is to discredit me," said Somers of Utian. "And I'll tell you why his job is to discredit me. Because his job is to represent the pharmaceutical companies, and they know ... if we all figure out it's so simple to feel well by putting back what we lost in the aging process, we won't need all their drugs like me. I don't take a single drug. I'm not the kind of customer the pharmaceutical company wants."

Utian refutes that, and puts the responsibility back on Somers.

"It's her money, it's her body. She can do what she wants, but I think it's quite irresponsible ... to be suggesting to people to take medications that are not proven, that have not been adequately tested by the FDA and to make promises that those drugs will actually enhance life, quality of life, length of life," he said. "It's pseudo-science. It's nonsense."

Empowering Women

Somers is accused of making herself a human guinea pig, and critics say there is not a lot of financial data and practically no scientific data to back her up.

"I never give advice," said Somers. "I say, 'What do you have Suzanne.' ... This is the way I've gone. If you want what I have, go that way. Read up about it. Read my books. Be empowered by information."

But what woman wouldn't want to be just like her? She's rich, she's beautiful and she doesn't look her age. But a lot of what she suggests in her book is not scientifically proved.

"How long are you going to believe this? How long are you believe this?" she asked. "How long are you going to believe information that's coming from pharmaceutical companies who make drugs that people think they need."

Somers is quick to point out that she isn't selling hormones. She's simply selling a book.

But she acknowledges that between her books and her food and her products, Suzanne Somers is more than a human being -- she's a brand.

"I take every word I write in my books seriously," Somers said. "I have daughters. I have granddaughters. I want for them to have health."

Despite the storm she has created around herself, Somers is unapologetic.

"When I get criticized for what I do," she said, "I think of all the women who throw their arms around me and kiss me and call me, and I love being a champion of women. I love it."