Past the desert scrub and cacti, at the end of a long drive to nowhere, sits a fenced-in oasis guarded by a big gate. Press the secret code and you enter a paradise: a spa where the rich and beautiful flock to purify their bodies from the chemical excesses of 21st-century existence.

"Between the stresses of everyday life (deadlines, relationship struggles, traffic) and the impurities found in processed foods, the body is full of toxins and the mind, tension," declares the Web site for the We Care Spa. "We Care is leading the new movement of detoxing the body and hence, the body and soul."

Guests go without solid food for anywhere from three to eight days, subsisting on a liquid diet that supposedly helps flush their systems of pollutants and preservatives while providing vital nutrients.

They gulp down 14 individually formulated drinks daily to boost their energy and loosen stuck matter in their colons. They imbibe endless cups of fresh vegetable juice, gallons of blood-purifying tea and enough water to grow a tree in the desert.

Then, packed to the gills with fiber and herbal laxatives, they receive colonics, lymphatic massages and Korean skin scrubs to help flush the toxins.

A spa such as this, with a price tag that can run into the thousands, is definitely for the well-heeled. But its focus on detox is part of a larger alternative health trend that has been briskly growing in the past few years. Celebrities and health faddists both do it.

Through scouring out their innards, drinking gallons of liquid and popping pills and powders, these enthusiasts hope to purge themselves of accumulated metabolic waste and man-made poisons — fighting disease, sharpening minds, increasing stamina and (with all the intestinal flushing) flattening bellies.

A plethora of DIY detox books are available to help them, and a bevy of detox products exists on health-store shelves. In fact, cleansing and organ supplements (largely consisting of herbal-based cleanse and detox kits) are the fastest-growing segment within the herbal formulas category, says David Browne of SPINS, a market research and consulting company for the natural products industry. Last year's growth was twice that of the year before, he says.

WATER AND MORE WATER

Most people who do detox regimens speak of them with the zeal of religious converts.

But medical professionals urge caution. They say detox diets can be potentially dangerous — and that there's no evidence that the diets do any good.

"The idea that foods are poisonous, or that we need detoxification or a cleansing regimen to improve our health is without scientific merit," says Roger Clemens, a nutritional biochemist at the University of Southern California's pharmacy school. "We have wonderful organs, great enzymes, a great system for eliminating toxins naturally."

The perennially popular Master Cleanse — in which people survive anywhere from three to 40 days on little more than a brew of lemon juice, cayenne pepper, maple syrup and lots of water — was created 60 years ago. We Care has helped guests try to cleanse their bodies for 20 years. But today's detox craze is something different, according to those watching the trend.

"What I think is new about it is the commercial component, the increasing economics of detox dieting," says Dr. Peter Pressman, an internist at Los Angeles' Cedars-Sinai Medical Center, who has written on the subject. "Over the last three years it has become an international industry."

Most detox diets involve consuming large volumes of water, huge quantities of crushed raw vegetables and daily doses of digestion-aiding, colon-scouring supplements such as fiber and herbal laxatives — accompanied by colonic irrigation or enemas.

THAT URBAN GLOW

Claims vary depending on the diet, but testimonials generally suggest that these regimens will boost energy, increase mental clarity and make skin glow.

Such diets seem to resonate with an often-affluent urban psyche that seeks to cure all through health and nutrition, and to fit neatly into this age of instant gratification and pervasive fears about environmental pollution.

"What appeals to people about these detox regimens is you are doing it all at once," says Susan Bowerman, assistant director of the Center for Human Nutrition at the University of California-Los Angeles. "It's like getting your oil changed."

David Oyster, a disc jockey in Colorado, recently completed a five-week detox diet that lasted. He had tried detox cleansing before, he says, including the Master Cleanse. That left him so depleted he could barely function.

But four months ago, he tried again because he felt sluggish. Under a nutritionist's supervision, he took pills and powders with names such as Toxinout (with L-cysteine to detoxify the liver, kidneys and blood), ParaDetox (to flush the system) and Oxy-Powder (to oxygenate the colon and remove toxins). And he loaded up on fiber.

At night, he took yet more pills, including a probiotic supplement to repopulate his intestinal flora. "I felt more energetic, more able to do brain work, more mentally alert and refreshed," he says. "I sleep better, my senses are more acute.

"I made science documentaries for years. I was kind of skeptical about this. But I decided to try it, and it was a miracle!"

WANT FRIES WITH THAT?

Dr. Nancy Lonsdorf, an internist and former director of the Maharishi Ayurveda Medical Center in Washington, D.C., says the body is designed to get rid of toxins naturally — but in today's world, that might not be enough.

"If you are feeding someone Big Macs, french fries and making them work hard, having them breathe toxic air, (drink) toxic water, then yes, the body is getting rid of toxins, but it is taking in more than the body was designed to handle," she says.

Lonsdorf notes that the Centers for Disease Control and Prevention has begun taking blood from thousands of people, testing for pesticides and toxic compounds and following them over time, to measure Americans' chemical exposure. In a 2005 report from that project, the CDC screened for 148 toxic compounds in the blood samples and found measurable amounts of more than 100 of them present.

Some chemicals, such as phthalates, are metabolized fairly quickly. Others, such as PCBs and dioxins, can accumulate in the bones, muscle, lungs, liver and, perhaps most frequently, fat.

"Toxins do build up," Lonsdorf says. "Doctors have to face it. It is not the case that we can get rid of whatever garbage is going in."

However, several studies in the 1980s examined whether eating oat and rice bran — fiber — could help reduce levels of fat-soluble compounds such as PCBs and dioxins, Birnbaum says, and concluded that bran had only a small effect. Raw vegetables, meanwhile, don't have any special detoxifying properties, experts say, except that they bulk up stools with more fiber, helping with elimination.

In fact, most scientists say there is no evidence that these often extreme cleansing methods do anything except perhaps dehydrate you and throw off your electrolyte balance. When people do the regimens to excess, they can get muscle cramps or pass out, sometimes even push their kidneys to begin to shut down.

"It is fraud," Cedar-Sinai's Pressman says. "It is a distortion and misapplication of science and medicine. Kidneys and livers don't need rest. They don't need water in huge quantities. What they need is to be used. Our body's own capacity to detoxify itself is beyond anything we can design."

Susana Belen, the 68-year-old founder of We Care Spa, is not swayed. "Just because it hasn't been scientifically certified does not mean benefits do not exist. It means no one took the time to prove all of this," she says.

Look at her: She has no pain, takes no medication and has the same pulse she had when she was 28. This — and that 80 percent of her guests return to the spa — is evidence enough that it works, she says.

Lounging on sofas, the guests at her spa quietly talk — of psyllium, digestion and hunger. "You should have seen what came out of me!" exclaims one woman, referring to the black goo that emerged from her intestines during a colonic irrigation.

Belen encourages guests to drink a little asparagus water daily and tells them artichokes are the best food for the liver.

"If you do detox, and you don't go home and do changes, this is all totally useless," she says.