What do you think of when you hear the words cottage cheese? What about if we throw in some orange peel? Are you picturing some kind of weird cottage cheese and orange peel salad, or are you thinking about the tops of your thighs, a loved one's thighs or perhaps those of an unfortunate celebrity?

If you are a woman over 30, there's a 90% chance you've been afflicted at one time or another by cellulite. British women spend £30m a year on slimming creams. And there's more than just creams to tempt us. As far as anti-cellulite treatments go, we're spoiled for choice. You can get zapped by electric currents; you can have injections of homeopathic substances in your bottom; you can be pummelled by rollers, suction pads and all manner of other implements; you can sit in a space-age pod; you can be wrapped in seaweed and clingfilm; you can drink anti-cellulite tea; you can stick caffeine-loaded anti-cellulite patches on your skin; you can wear jodhpurs that claim to massage away the cellulite; and you can even wear tights with capsules in them which promise to "stimulate the breakdown of fatty tissue".

That's a pretty impressive array of treatments for something many scientists claim doesn't exist, and which the British Medical Journal labels a "non-disease". In the medical profession, there are two schools of thought as far as cellulite is concerned.

School one: there is no such thing as cellulite. It is a polite way of saying "fat", a huge con created by the cosmetics industry to part us from our money. "Cellulite is no different from any other sort of body fat", "babies have cellulite", and you'd be better off saving your money and walking up the occasional flight of stairs than bothering with any of the hundreds of anti-cellulite creams or treatments on offer - that's what the doubters think.

School two consists of those in the beauty and cosmetics industry who spend an awful lot of time, money and energy trying to find a cure. We're not just talking about greedy multinationals, but otherwise respectable types such as doctors and scientists. Would they really waste their careers and risk their professional reputations chasing something that doesn't exist?

"Of course cellulite exists," says Dr Victor Hyde, scientific adviser for L'Oréal, whose Perfect Slim range is the market leader ("Perfect Slim was chosen by one woman every 10 seconds last summer," goes the hype). "Ask a million women who suffer from it; they know. We all know what we are talking about when we talk about it, it's pretty obvious if you have or haven't got it - whatever you call it." But then, he would say that.

So what, exactly, is cellulite? Is it fat by another name that we should simply learn to live with, the physical result of a build-up of toxins in the body (caffeine, alcohol, take your pick), or a quirk of nature to which some of us have a genetic predisposition?

Just about the only thing the boffins agree on is that the appearance of cellulite - that dimpled look - is caused by fat cells protruding from the latticework, or "honeycomb", of fibrous tissue around them. "There is a fine meshwork of a restraining net underneath the skin which keeps fat in place," says dermatologist Dr Victor Neel, of Massachusetts general hospital, Boston - one of the few expert voices on cellulite who is also independent.

Cellulite occurs when that net barrier is ineffective and allows the fat beneath to push through, hence the look of dough in a string bag. "These cells swell and can clump together in the underlying areas of the skin [the dermis and hypodermis], giving rise to the characteristic pockets of orange peel skin which may become visible," says Hyde.

Cellulite does not differ from "normal" fat, it differs only in the way it is held and distributed in the body tissues. The actual chemical nature of the fat is not different from other body fat.

But if you ask what causes this mesh netting to break down, these otherwise normal fat cells to swell and clump together, and what can stop this happening, you'll get a different answer depending on whom you ask.

Even within the cellulite industry there is little agreement. You can just about find people who agree that cellulite is the body's natural way of storing excess fat, and that as women are more likely than men to store fat around their hips, thighs and bottoms, they are naturally more predisposed to the dimpled, orange peel look. That cellulite is in some part genetic is also considered "fact", but that's where the agreement ends. For some, it's all about toxins; for others, it's about plain old fat.

Take the question of why thin women get cellulite. The toxin camp will argue that this proves their point - after all, being thin doesn't mean being toxin-free, or even having a healthy diet. The "fat" brigade will point out that even thin women have to store fat somewhere, and it's usually on their bottoms. Hence, a skinny model will suffer from cellulite.

"Fatty deposits and toxin build-up under the skin around the thigh, tummy and bottom" are what causes cellulite, says Kirsten Day, of Shiseido. Its Body Creator anti-cellulite gel caused such a storm when it was launched at Selfridges in 2002 that it sold out on the first day, with sales amounting to £85,000. Over at L'Oréal, toxins are deemed a red herring: "There's no evidence to show toxins are cellulite," says Hyde, which means if you're busy detoxing (hoping it will get rid of cellulite), you might be wasting your time: "Detox will flush the liver and kidneys, but not get rid of cellulite. It will improve your general health, but not get rid of fatty tissue."

With regard to the "too much caffeine leads to cellulite" theory, Hyde is equally sceptical: "I've looked at as much literature as I can, and found nothing to support the idea that coffee and tea can be a cause." But don't go celebrating with a double espresso just yet. According to Day, detoxing, drinking plenty of water and, of course, investing in a good anti-cellulite cream (one that makes anti-cellulite claims, rather than vague "body contour" promises) are the best ways to rid thighs of their dimples.

With all this conflicting advice, it's no wonder we are confused.

One thing cellulite is not, though, is new - so don't listen to anyone who tells you it's a scourge of modern living. Renaissance oil paintings depicted voluptuous ladies riddled with the stuff, and the word itself was coined in the 1920s by French doctors. It's just that it's more noticeable now because we're more prone to baring our flesh.

Why do men rarely get it? Partly because women have more body fat than men, particularly around the stomach, thighs and bottom (to protect the reproductive organs), and partly because the fibrous structure that supports the fat cells is thought to be different in women. And the only reason it affects thighs more than, say, arms is that the fibrous tissue in the thigh is different from anywhere else.

Most dermatologists agree that cellulite is "physiologically normal", says Dr Tamara Griffiths, consultant dermatologist and member of the British Skin Foundation, but as for the plethora of explanations, advice and treatments, "There's a lot of pseudoscience being spouted." A lot of products in beauty are driven by marketing rather than by robust scientific research. In order to conduct proper deductive research, the trials need to be "double blinded" - with both subject and investigator unaware of which product is being tested.

"Anti-cellulite products may improve the superficial texture of the skin," says Griffiths, "but I think a lot of their popularity is to do with a placebo or psychological effect: people feel better because the product is nicely packaged and costs a lot. It's a psychological boost. The customer may feel more confident having used it, but that's different from actual physical results."

She says the same goes for spa and clinic treatments. "You're paying for a boost to your mood, for a pleasant spa experience and feeling pampered and relaxed for an hour or so - which is fine, as long as you know what it is you're paying for. In cold, hard, clinical terms, that's really all it is."

But listen to those in the cellulite industry and they'll tell you that the research is there; you just have to get over the fact that it's been carried out by companies with a vested interest in the result. "We have one customer who dropped a jeans size, and she swears she doesn't exercise," says Day at Shiseido, referring to an in-house trial that measured 20 women after four weeks of using the Body Creator gel twice a day. There was an average decrease in hip measurement of 1.3cm, and an average weight decrease of 1.1kg, the company claims.

The makers of Guam Seaweed Mud, made from marine algae and mostly for use in salons (you can do it at home, but it involves wrapping yourself in clingfilm), claim that the decrease obtained after just one application measures "about 2cm". They also point out that, as part of a Guam treatment, the client's legs can be measured before and after application to prove results, so you can literally see for yourself.

Decléor says it achieved a 1.5cm reduction in measurement with its research when using a combination of two Decléor products, Aromessence Contour and Expert Contour. It also used scanning techniques for its research (more reliable, says the spokesperson, than a tape measure test), showing an average fat decrease of 21% over 28 days.

So what about comments that such products offer only a psychological boost? "How can it be in the mind when you've got the test results?" asks Decléor.

L'Oréal, meanwhile, is keen to point out that it's not just its own internal research that has shown positive results. Last year, 60 Millions de Consommateurs, the French equivalent of Which? magazine, found that volunteers using both L'Oréal Perfect Slim and Elancyl (which came joint top in the test) lost up to 2cm from around the thigh after 14 days (though without further improvement after that). In the previous three tests conducted for the magazine, no cream had proved more effective than a simple thigh massage. Perhaps progress is genuinely being made, and these creams are in fact working - but, if so, how?

"The most common and effective active ingredient in cosmetic anti-cellulite products is caffeine," says Hyde. "This helps to encourage the metabolism of the fats and the draining of accumulated water from the fatty tissues." So, for example, Perfect Slim Patch, L'Oréal's latest addition to the anti-cellulite range, provides "a reservoir of caffeine that is slowly distributed into the areas of the skin on which the patch is placed".

These days, any self-respecting anti-cellulite cream contains caffeine in some form. "We use caffeine complex ," says Shiseido's Day. "It's like caffeine, but liquefied, like a concentrate. A coffee granule rubbed over your body will not work, but the caffeine complex turns excess fat into free fatty acids. It liquefies fat so it is able to burn off within the body."

But while caffeine may have been shown to shrink fat cells in a laboratory situation, that doesn't mean it will have the same effect once turned into a cream and applied to the skin. "Caffeine has never been shown to my level of satisfaction to do anything when applied topically," says Dr Neel of the Massachusetts hospital. "Creams are a waste of money." The same goes for any of the treatments available. Of endermologie (a sort of combination of heavy rollers and vacuum suction applied to the skin), the grande dame of cellulite treatments and often heralded by beauty writers as the only treatment that works, Neel says, "The latest studies have shown it not to do anything." He cites colleagues who were offering endermologie but have now stopped.

Neel is also "very suspicious" of laser therapy: "It may create a temporary swelling, which will give the impression of improving the skin, giving it a smoothing effect, but it won't address the real problem." He is equally dismissive of mesotherapy, the "cure" that involves having a concoction of vitamins and minerals injected into your buttocks.

If there is a cure for cellulite, it's safe to say that no one has yet discovered it. There may be creams that temporarily improve the appearance of the skin, or treatments that make the thighs look firmer after a rigorous massage; there may even be something in the application of caffeine. But don't pin your hopes on it. In fact, don't pin your hopes on anything in a bottle; or, as Neel puts it, "Try not to fixate on it. Have a good diet and plenty of exercise."

Creams

Caudalie Slimming Treatment Oil The box doesn't say 'makes you thin', but talks of 'improving the lumpy appearance of the skin'. Applying the oil was not dissimilar to creosoting a fence. Does it work? Not so as you'd notice after a couple of weeks, but that doesn't mean it isn't nice. £32, 020-7304 7038.
SS

Shiseido Body Creator Applied twice a day for roughly four weeks (I struggle with routine), this left my skin soft and smooth. Definite improvement noted; with more effort, it might be even more effective. £40, 020-7313 4774.
SB

Clarins Body Firming Cream In the six weeks I used this, I went to the gym almost once a week. Had I become miraculously slender-thighed, I would not have been able to say with confidence how this had come about. My skin did look peachier, but this might have happened had I massaged in a similar amount of margarine. £30, 0800 036 3558.
JCM

Decléor Contour Balm I've always been sceptical about cellulite creams, but Decléor's Contour Balm did smooth some of my inroads. Unfortunately, you have to rub it all over at night, so you go to bed resembling a basted chicken. I'm afraid I slacked off the regime rather prematurely. £33, 020-7313 8780.
HF

Elancyl Lipo Reducing Concentrate In France, testers' thighs shrunk by up to 2cm with two weeks' use of Elancyl Lipo Reducing Concentrate. I wasn't trying to reduce the size of my legs, just iron them out a bit, and this certainly did that. £19.95, 01582 820150.
PC

L'Oréal Perfect Slim Cold. That seems to be the common factor with cellulite creams. After a week I thought I could see a difference. Then I realised one of the lightbulbs in my bedroom had gone. Day, £9.99; Night, £10.99, from Superdrug and Boots nationwide.
HP

Treatments

Ultracel Exfoliation is followed by anti-cellulite cream, fresh Royal Jelly and essential oils. Next up, 10 minutes' rubbing with the ultrasound nozzle, then 10 of massage with a suction head to boost circulation, 10 of a freezing applicator, then a final application of cream. Multiply the lot by six. The result? Smoother, tighter skin, and flesh that felt less bumpy. From £35, 0870 777 7818. Six sessions recommended.
BM

Advanced Keymodule Endermologie The granddaddy of cellulite treatments. After my first session of being pummelled with rollers, my entire body felt sore. Future sessions were less painful, enjoyable even. Could I see an improvement? If you look for anything long enough, you start to see it, but then again, I didn't last the course. From £40, 020-8731 5678. Ten sessions recommended.
HP

Eporex Electric pulses connect a circuit through a pad on your hand and a roller that's rubbed over affected areas with a herbal concentrate. Exercise and abstinence from nice food and alcohol are also recommended, so the initial improvement was short-lived. £80, 020-7499 1904. Six to eight sessions recommended.
SB

Elemis Fennel Cleansing Cellulite and Colon Therapy Said to be 'colonic irrigation without the tube', you give over your tummy to your therapist and feel your, ahem, 'blockages' move. The theory is that cellulite is associated with poor circulation, fluid retention and a congested digestive system, so mere thigh-rubbing is not enough. Still, there's plenty of that, with skin brushing, a fennel body mask, massage of hips and thighs, and reflexology too. My thighs were much smoother after the course. From £50, 01278 727830. Six sessions recommended.
KV

BeautyTek First the consultant photographed my thighs, then a low-frequency electrical impulse, said to break down cellulite cells, was passed into these pockets of shame. After eight sessions, my buttocks were a better shape and my thighs slimmer, but a few months on, I'm seeing a return of the dimply stuff. £100, 0845 060 1758. Ten to 12 sessions recommended.
CR

American Body Wrap You strip to underwear, you're measured all over, covered in a slimy serum, wrapped in bandages and binbags, and left to lie under warm blankets for half an hour. Unwrapped, I'd lost three-quarters of an inch from my waist, one and a quarter from my left calf. It should stay off for a week or two, if you abstain from alcohol and coffee. £65, at IMA, 020-7328 6616. Six sessions recommended.
JCM

E'Spa Stimulating Hip And Thigh Treatment Deserves an award for what it fits into 55 minutes: body brushing, exfoliation, lymphatic drainage, deep-tissue massage, an algae wrap, and head or foot massage. How could cellulite survive? After three sessions, my thighs felt fab. Around £90, E'Spa, 01252 352230. Six sessions recommended.
GM

Testers Stevie Brown, Jess Cartner-Morley, Paula Cocozza, Hadley Freeman, Priscilla Kwateng, Grainne Mooney, Brigid Moss, Hannah Pool, Caroline Roux, Susie Steiner, Katharine Viner.