Despite all the magazine ads for products that promise to melt, steam or vibrate away the lumps, bumps and bulges of cellulite, all those pitchmen will succeed in shaking loose may be a little of your money.

No special treatment exists for cellulite, say the medical experts, because cellulite itself doesn't exist. The bulges that plague the hips of some women are filled with just plain old fat.

Cellulite was "discovered" in the early 1900s by operators of European health spas, and spread to the United States in 1973, when Nicole Ronsard, owner of a beauty (and cellulite treatment) salon in New York, published a best-selling book on the subject.

That book, which sold more than 200,000 copies, triggered a fad that quickly swept America. More books were written. Magazines explored the pros and cons of cellulite.

And, as might have been predicted, a plethora of products and treatments sprang up -- all claiming to eliminate cellulite. Despite the best efforts of federal authorities, many of those, or their successors, are still in the marketplace.

The cellulite myth is based on two basic, and false, contentions:

Cellulite is not normal fat; it is a gel-like substance trapped in lumpy, immovable pockets of water, fat and toxic wastes just beneath the skin. Those deposits are created when the kidneys, liver and digestive system fail to adequately eliminate wastes.

Since cellulite is not fat, it cannot be eliminated by dieting; only extraordinary treatment (the choice of the best one depends on who's making the pitch) can get rid of it.

The cellulite myth is based on tiny particles of truth: Women do develop unsightly, bumpy, hard-to-get-rid-of masses around their hips, thighs and buttocks.

But, medical scientists agree, those bulges are nothing but ordinary fat.

"The first viewpoint of the medical community is that there is no such condition as cellulite," says Dr. Harold Lubin, director of the American Medical Association's personal health and food and nutrition programs. "Fat is fat. The idea of fat cells containing toxic wastes is not defensible."

A scientific study conducted at Johns Hopkins University by Dr. Neil Solomon, a former Johns Hopkins professor now in private practice specializing in nutritional problems, supports that view.

Solomon took samples of fat from the thighs, buttocks and hips of women who thought they had cellulite and from those of women who didn't have the dimpled, orange-peel appearance said to be cellulite. The samples were turned over to a team of pathologists who did not know which ones came from which women. The results:

"There were no differences in the samples; it was all just plain old fat," Solomon says. "There is no such thing as cellulite. And since there is no cellulite, there is no specific treatment for it . . . nothing magical you can take that's suddenly going to make lower body fat disappear."

Another scientist who ridicules the cellulite concept is Dr. Grant Gwinup, professor and chairman of the division of endocrinology and metabolism at the University of California at Irvine.

Gwinup says he challenged "cellulite removal" spas and manufacturers of "cellulite removal" products to participate in a massive study to determine whether any of their treatments or products actually would eliminate lumpy lower body fat. All declined, he says.

The facts about fat, according to Gwinup, are these:

There are only two kinds of fat, white and brown, and each serves a specific purpose. White fat stores energy and provides the fuel our muscles need to function. When the body doesn't get enough exercise to use all the calories consumed in the diet, excess fat develops. That, Gwinup says, is what "so many of us fight against every day of our lives."

Brown fat, on the other hand, is buried in minute quantities deep within the body, where it helps provide the heat our bodies need.

Some researchers suggest that those well endowed with brown fat tend to store less white fat and therefore don't become obese, regardless of diet or lack of exercise, says Gwinup.

Because of differences in hormones, women tend to store most fat in the lower portions of their bodies -- thighs, hips and buttocks -- and men in the upper portions, the abdomen.

That's a plus for women because when fat collects around the lower part of the body, it may be less likely to contribute to some of the major problems thought to be associated with upper body fat, such as heart disease and diabetes.

"Female lower body fat sometimes takes on the bumpy cottage-cheese, mattress-like, or orange-peel appearance called cellulite because a woman's skin is connected to the muscle coverings by thin strands, much in the way a mattress is put together," says Gwinup.

"When the spaces between those strands become engorged with fat, the strands don't stretch, so the covering skin bulges outward, creating the unsightly, bumpy appearance women hate so much."

He says men rarely suffer that condition because their skin is connected to the muscle covering differently, and they have generally thicker skin, so it doesn't bulge outward as easily as in women.

A woman doesn't necessarily have to be obese to have the condition called cellulite; researchers have found there is a definite genetic factor. If a woman's mother or grandmother had it, the woman need be only a few pounds overweight for it to appear, says Gwinup.

A research team in Germany studied four generations of females from the same family and found that even the youngest, an 8-year-old girl who was overweight but not obese, showed signs of the mattress effect in her lower body.

With all this, the fact remains that many women (the cellulite removal industry claims eight out of 10) suffer the embarrassment of hard to budge pudge on their lower bodies.

What can they do about it?

Again, medical scientists are in agreement: Reduce daily calorie intake and increase exercise. It may take a while, but as the excess fat disappears, so will the lumps.

Gwinup believes there is no point in trying to achieve spot reduction of lower body fat.

"When you exercise your thighs, a signal goes out to fat deposits all over the body to supply fuel for the muscle activity -- that fuel doesn't come only from the fat directly over the muscle," he says. "Obviously, there is nothing to the theory of spot reduction of fat."

"While we cannot eliminate fat through spot reduction, exercises which work the lower body muscles -- brisk walking, bicycling, skating, aerobic dancing -- not only burn off excess fat throughout the body, but also help tighten the muscles in the thighs and buttocks and that tightness gives them a better appearance," he says.

"But brisk is the operative word; the more strenuous the exercise, the more oxygen the body consumes, and oxygen consumption is one of the keys to using excess fat. An hour a day of brisk walking alone, without dieting, could put most women back into the shape they'd like to see in their mirrors."

Dr. Frank E. Young, U.S. commissioner of food and drugs, sums up the situation.

"Pills, potions and devices with claims that they will get rid of so-called cellulite are part of the endless parade of quack diet and figure control products," he says. "FDA has taken legal action to have numerous quack 'cellulite removers,' such as electrical muscle stimulators, seized and destroyed.

"While references to cellulite may help sell books and beauty aids," he adds, "the fact is that fat is very much the same, no matter where it's found on the body. Though it may not be glamorous, the only safe and proven way to get rid of fat is to exercise more -- and eat less."