(USA TODAY) -- The claims for the products hold much promise: "Clinically proven to reduce the appearance of cellulite within eight weeks." "Refines body contours by minimizing the appearance of spongy skin."

Anti-cellulite creams from many leading cosmetics and skin care companies, including Avon, L'Oréal and Neutrogena, are supposed to help improve the appearance of women's cellulite -- that dimply, cottage-cheese look on their hips, thighs and buttocks -- without exercise.

These kinds of products are popular in France and are beginning to take off in the USA. Ads are cropping up in magazines and on TV.

And many women appear to be taking a chance, shelling out $5 to $50 or more a pop. They spent more than $9.3 million last year on cellulite-fighting creams from three major companies, up from $4.5 million in 2001, according to ACNielsen data provided by L'Oréal.

Is it possible these products made of ingredients such as caffeine, vitamins and green tea extract are the answer to the prayers of millions of women who would do almost anything to get rid of that lumpy flesh that leg lifts can't conquer and diets can't kill?

Yes, indeed, say the believers.

"They absolutely, positively work to improve the appearance of cellulite," says Mitchel Goldman, a dermatologist in La Jolla, Calif. "The questions are: To what degree, how long do they work, and which product is best?"

Hogwash, the critics say.

"You can buy creams that contain vitamins, herbs, minerals and antioxidants and all the popular buzzwords, and they mainly make the skin a little softer and maybe a little smoother," says Albert Kligman, professor of dermatology at the University of Pennsylvania School of Medicine in Philadelphia. Many of the promises are "merchandizing hype," he says, and women with a lot of cellulite won't get the results they want.

The effectiveness of most of the ingredients used in the creams isn't backed by scientific evidence, he says.

So what's a woman to do?

Women can't look to the government for guidance because cosmetic products are not regulated like drugs, which have to be proven safe and effective before going on the market. However, companies do have to toe the line in what they say about the creams or risk getting into trouble with the Federal Trade Commission.

Heather Hippsley, an FTC attorney, says claims about changing the skin's appearance are usually OK. But the agency generally looks into claims for permanent changes, inch loss or weight reductions. If the company makes such a claim, it must have research to back up the promise, she says.

The labels and ads for most of these products stick with appearance claims and don't make permanent fat-loss promises.

Exercise helps

For years, women have been desperately searching for ways to get rid of this troublesome fat. They've tried surgery, deep massage, roller techniques, wraps, pills and potions.

Cellulite is not a medical term; it's actually a name coined by the French to describe the dimply, orange-peel look of the skin above the fat on women's hips, thighs and buttocks. It is common in women and usually begins during adolescence.

Rather than "wasting money or time" rubbing cream on their thighs and hips, women should exercise and lose weight, says Rod Rohrich, president-elect of the American Society of Plastic Surgeons and chairman of the plastic surgery department at the University of Texas Southwestern Medical Center in Dallas.

"It'll make it look better, but it won't go away completely," he says.

Others agree. Women will lose some "of their lumps and bumps" if they drop weight and strengthen the muscles in their hips and buttocks with weight training, says fitness researcher Wayne Westport, author of No More Cellulite, written with Rita La Rosa Loud.

Westport conducted a study of 79 middle-aged women who did strength training and aerobics for 45 minutes three times a week for eight weeks. Some also dieted. Seventy percent reported they had "a lot less cellulite" after completing the exercise program. The rest said they had "less cellulite," he says.

But using a cream seems so much easier to women who have tried and failed at ridding themselves of dimply fat.

Goldman bases his belief that the anti-cellulite creams work on a study he did on 10 women, published in Cosmetic Dermatology. He had them wear snug shorts that trap body heat at night and put a cream on only one thigh. Most noted an improved texture of their skin over their buttocks and a slight decrease in thigh circumference on the treated thigh.

Goldman says he has seen many women who have used creams and who have noticed a difference in the smoothness of their skin. He is working on his own product.

But Jeffrey Blumberg of Tufts University in Boston, one of the nation's leading vitamin experts, says there's no reason to believe these products make a difference. He says he is unaware of any conclusive scientific evidence that shows "significant and sustained improvement in cellulite by any nutritional ingredients."

Thin-skinned women

However, the companies say they have the proof in their own studies (most have not been published) and the work of others.

Kligman says one reason women have this orange-peel or cottage-cheese look is because they have more fat in their hips, thighs and buttocks and the skin that covers that fat is thinner than most men's, so the fat shows through the skin more. "If that skin was as thick and dense as men's, you'd never have cellulite."

One ingredient used in many products is retinol (vitamin A). The body converts it to retinoic acid, which is the active ingredient of Retin-A. Kligman says companies may be adding retinol to their cream, building on his discovery of how Retin-A is helpful for the treatment of acne and wrinkles.

However, he says, some of the anti-cellulite creams have only a "little dollop" of retinol, so the concentration is probably too low to have any effect.

But there are probably some products that have enough retinol of the right type and concentration in the right kind of base to make the skin a bit firmer and more solid so the fat doesn't pop through as much, Kligman says. "It doesn't change the fat underneath, but it may improve the appearance of cellulite."

Art Pellegrino, director of research and development for Johnson & Johnson, the makers of RoC Retinol Actif Pur Anti-Cellulite Treatment, says the primary benefit of the product comes from retinol. "It's working on the skin, so you don't see the uneven look of the fat coming through the skin. It does make the skin's epidermis (the outer layer) thicker."

The company sponsored a clinical study of 46 women that showed that the product improved the appearance of cellulite by 39% after eight weeks of use. The research was published in the Journal of Cosmetic Science.

Theresa Chen, scientific affairs project leader for Neutrogena, also says the company's anti-cellulite cream contains retinol, which increases skin density, thus helping the skin hold its shape better.

Another common ingredient in these creams is caffeine, which is added based on theories that it might affect blood flow or fluid in the skin, or possibly act on the fat beneath the skin.

Avon Solutions Cellu-Sculpt Anti-Cellulite Slimming Treatment contains perilla seed oil, chaihu extract and caffeine, which block fat production and increase fat burning, says Robert Kalafsky, executive director of skin care, global research and development for Avon.

Experts skeptical

The idea to put caffeine in these lotions may be based, at least partly, on a couple of small studies done years ago by obesity researchers Frank Greenway, George Bray and others at the Pennington Biomedical Research Center at Louisiana State University in Baton Rouge. They found that aminophylline, an ingredient that acts like caffeine, decreased the size of women's thighs by an inch after a month of use.

Greenway says they suspected that aminophylline caused the fat cells to give off their fat for either use as energy or storage somewhere else on the body. In theory, caffeine would work the same way.

The researchers couldn't get caffeine to work in different cream bases, Greenway says, although it may be possible that cosmetic companies can do that now.

Kligman is doubtful the caffeine can penetrate the skin well enough to get down into the fat. "Nothing gets through the skin easily."

In the end, most experts are skeptical, and even those who see some promise in the products acknowledge that not enough research has been conducted and published that proves these creams are effective.

So until those studies are done, the ads will continue to beckon. And when it comes to judging the truth of those promises, women are on their own.

Copyright 2003 USA TODAY, a division of Gannett Co. Inc.