By ABBY ELLIN Randall and Katherine Hansen, who live in DeLand, Florida, have made a ritual of doing the“Fat Flush Plan”at least once a year“to cleanse our bodies and help break some bad habits,”said Mr.Hansen, 48, president of Quintessential Careers, a career guidance Web site.

The regimen, publicized by the nutritionist Ann Louise Gittleman in a 2001 book, mostly targets the liver, which Ms.Gittleman believes is less able to metabolize fat because of toxins absorbed orally or through the skin. Her plan includes a low-carbohydrate, highprotein menu of about 1,200 calories a day, with no alcohol, caffeine, sugar, grains, bread, starchy vegetables, dairy products, fats or oils (save flaxseed oil). She also recommends a“Long Life Cocktail”of diluted cranberry juice and ground flaxseeds, or a teaspoon of psyllium husks, in the morning and evening; and a mixture of cranberry juice and water throughout the day. Ms.Gittleman sells a Fat Flush kit for $112.50 with herbs and nutrients like dandelion root, milk thistle and Oregon grape root.

“It’s horrible when I’m on it? I feel very deprived,”said Mr.Hansen, who credits the program with helping him lose more than 30 kilograms.“But I always feel better after, and I end up dropping about 10 pounds [4.5 kilograms] in the two weeks? an added bonus on top of the detox.”

The Hansens are among the thousands of people who regularly“detox”in an effort to rid the gastrointestinal system of unsavory substances that proponents believe build up and can cause allergies, exhaustion and certain cancers.

But many Western doctors question the legitimacy of the regimens and their claims of promoting good health, believing detoxification does little to no good, and is possibly harmful.

“It is the opinion of mainstream and state-of-the-art medicine and physiology that these claims are not only ludicrous but tantamount to fraud,”said Dr.Peter Pressman, an internist with the Naval Hospital in Jacksonville, Florida, and a critic of detoxification. “The contents of what ends up being consumed during a‘detox’are essentially stimulants, laxatives and diuretics.”

Such opinions have done little to deter the growing interest in the practice. Detoxification is enormously popular, according to SPINS, a market research and consulting firm based in Schaumburg, Illinois, that caters to the natural and organic products industry. Sales of herbal formulas for cleansing, detoxification and organ support among natural food retailers were more than $27 million from December 2, 2007, to November 29, 2008.

“Western medicine is treating the symptoms instead of addressing the root cause,”said Edward F.Group III, a Houston-based naturopath with theholisticoption. com, an online resource for the alternative wellness community.“We basically have a world that’s constipated. It’s like if you change your oil in your car but never change the oil filter. Ultimately it gets so full of sludge the engine’s going to break down.”

The goal of detoxification is to remove that sludge. Indeed, most regimens? whose benefits have been espoused by celebrities like Beyonce Knowles, who claimed to have lost 9 kilograms before the movie“Dreamgirls”on the Master Cleanse, a concoction of lemon juice, cayenne pepper, maple syrup and water? typically involve fasting, food restriction, nutritional supplements or a combination thereof.

Most regimens eliminate caffeine, alcohol and nicotine; some limit meat and solid foods and rely on unusual juice blends (cayenne pepper and lemon, for instance), all in an effort to rid the gastrointestinal system of pesticides, dioxins, polychlorinated biphenyls (PCBs) and food additives? in other words, just about anything you have eaten, drunk, smelled, inhaled or looked at that isn’t organic.

Because many holistic doctors believe that one’s bowels should be irrigated as much as four times a day, some detoxers rely on colonics, enemas and herbal laxatives to move things along. Others rely on liquid fasts, herbal supplements, colonics and formulas.

As the number of products and treatments grows, critics continue to emphasize what they say is a lack of scientific evidence that detoxification actually works.

As Dr.Frank Lipman, a specialist in integrative medicine in New York puts it:“People are selling a product. There’s a difference between selling a product and practicing good medicine.”