Clinical trials published last week show that the controversial Atkins diet really can help people lose weight. That's not news to Suzanne Levy, now a size 12

As moments go, it was one of the sweetest. I'm in the changing rooms, trying on a skirt. It fits - and it's a size 12. I'm blinking, squinting at the label. Is this a mistake? I've been a 14, and then a 16, for years. But there's no mistake - I look at the mirror, see my newly slim shape, and feel like weeping. I love Dr Atkins.

And it looks like it's not just me. Last week, the first clinical trials of the Atkins diet were published in the New England Journal of Medicine. The diet, which involves cutting out carbohydrates such as bread, pasta and rice, but eating plenty of protein and usually forbidden fats, has sold millions of copies and is much praised by celebrities such as Renée Zellweger. It has attracted plenty of controversy, too. Yet these trials show that people lose weight faster on this diet than using other methods and that it doesn't appear to damage your health, as its critics have suggested.

For me, it all changed last autumn. In the past, as an avid follower of a fat-free dietary lifestyle, I swear no globule of butter passed my lips for 10 years. Well, except when I fell off the wagon, which led to month-long eating-everything-I-could-find binges. This is the denial/yo-yo madness that many women will identify with. And a curious thing happened during this decade of (mostly) fat phobia: I steadily gained weight. Years of dry toasted bagels and plain jacket potatoes, and my reward: wobbly thighs. Last summer I was a bewildered size 16, feeling betrayed by a body not behaving the way it should.

But last October, I heard about the Atkins diet, and cautiously (and sceptically) began to allow all sorts of dairy, fat and oil into my life, feeling like a terrified vegetarian eating red meat for the first time. I banished carbs - out went rice, bread, pasta, potatoes. In came chicken, meat, fish and veg.

And today, I'm almost a stone lighter and pretty much a size 12. And the other amazing thing: I no longer think about food all the time, no longer see chocolate brownies hovering over people's heads as I talk to them, fantasising about going home and eating one. Instead, I find myself thinking "it's 8.45pm, you really must think about what to eat for dinner". I really have changed the way I think about food - the holy grail of diets.

I've been on and off diets since I was 14, when I wanted to look like Farrah Fawcett from Charlie's Angels. My own genetic inheritance had made me 5ft 2in with a fat-attracting behind, but that wasn't going to stop me transmuting into a blonde, white-toothed California beauty. So I drank low-calorie, chemical-tasting tomato instant soup (loathsome) and for some reason ate a lot of Melba toast, which in those days was bought at the chemist.

But my real diet mania kicked in during the early Nineties. I was living in New York, and the obsession of city women was fat. Not the dimpled bottom-loving kind, but the fat that seemed to lurk everywhere, ready to jump into your mouth and take a one-way ticket to your thighs. Which is when we banished it. Everything was fat-free - fat-free non-dairy ice cream, fat-free brownies, fat-free cream cheese, for god's sake. (What the hell was in it? Air?) My Manhattan friends and I would go to our aerobics classes and then reward ourselves at the frozen dessert counter, smugly thinking that while our taste-buds may have gone to no-taste-land purgatory, we were going to thin-thigh heaven.

But as I said, I never seemed to lose much weight. I have to confess that the only time I lost a substantial amount of weight was when I went to Weightwatchers. Weekly I ran into the lunchtime meeting with a meagre sandwich of low-calorie bread and one slice of turkey with mustard, to be patronised by an over-enthusiastic leader who - really - knew the precise calorie content of a teaspoon of every shop-bought salad dressing on the US market.

"Here's a good trick," she would trill proudly. "Dip the fork into the dressing - dip only - and THEN pick up your food - you get the taste but none of those naughty calories."

It was only when I started living in the UK again that I realised why I'd lost weight. In New York I'd exercised three to four days a week. In the long, dark UK winters, my will to move, let alone exercise, diminished, and the Danish pastries in the canteen loomed large at 4pm.

I put on weight. And I found myself having hormonal problems as the weight piled on. A couple of chats with a nutritionist, and it was suggested I ate less sugar. So out it went two Christmasses ago. All my favourite snack foods - I stopped them all. And then out went bread, a huge love of mine, also something suggested by the nutritionist. Instead, I ate oatcakes and Ryvita, with oatmeal for breakfast. Only complex carbohydrates for me, I thought smugly. And the butter was still verboten. Dry Ryvitas, dry oatcakes - mmmm, great life.

But the frustrating thing was I kept on putting on weight. I went from wearing 14s to 16s and loathed myself when I finally went out shopping and saw myself in a three-way mirror ("who is that blob of fat?")

I was too tired and stressed to exercise, I hated myself, and I hated the world. But at that time, a friend suggested we go to see a Pilates trainer in north London. I remember breaking down in sobs in the early sessions, so ashamed of my body, so convinced nothing would happen. I was still eating "healthily", hadn't eaten sugar in a year, but was still chunky. I angrily shouted at the trainer - "all I do is eat oatcakes and Ryvita - it isn't fair!" And he said calmly: "Well, they're still carbohydrates, aren't they?"

I stared at him with real anger and disbelief. I thought "you've no idea what you're talking about. I was given this diet by a nutritionist. Alright, just to prove to you you're wrong, I'll give them up as well, and show you that it won't make the blindest bit of difference."

So I cut out all carbohydrates. Out went the oatcakes, Ryvita, brown noodles, brown rice, potatoes. I ate eggs for breakfast, chicken and salad for lunch and dinner. And - something extraordinary occurred, something I wasn't expecting. With no extra effort on my part, and almost without noticing, the weight dropped off, just in that first week.

It turned out that much of that was temporary water loss - a common (and exciting) effect of a low-carb diet. But I continued this strange new way of eating. My cousin told me that he'd lost a lot of weight doing the same diet, and told me he'd followed the Atkins recommendations. So I bought the book and started on it for real. And when I read about how many people have problems with blood sugar metabolism - and even with oatcakes and Ryvita, which turn into sugar in your body - that made absolute sense. My father developed Type II diabetes when he was 50.

"Eat fat. Cheese, cream, full fat milk," commanded Dr Atkins. "I want you to be totally, shockingly unafraid of fat during these first two weeks." It was perplexing, to be told that all that I had been doing in the past was wrong, but I decided that I had nothing but my cellulite to lose, and went for it. Hovering over the dairy cabinet, I felt like I was going to commit a mortal sin. I shut my eyes, reached for the single cream, the brie... the butter. It was a beautiful home-coming experience.

Within six weeks, following what seemed to be a nonsensical diet of protein, vegetables and fat I'd lost near to 10lbs. But the amazing thing was I just wasn't hungry. And the constant desire to eat, to graze, was over. Once, my diet had been breakfast, sandwich at mid-morning, lunch, a couple of snacks in the afternoon before a three-course dinner at 8pm. Now, I was going to the gym at 7am (the weight loss spurred me to exercise again), eating fried eggs with pastrami and mushrooms, eating some nuts mid-morning, before a lunch of chicken, or salmon, or tofu and vegetables. And I noticed that as long as I didn't have bread, or pasta, or rice, or potatoes, I was stable, calm and craving-free.

So why no cravings? According to Dr Atkins it's because eating fat satisfies you in a way no other food substance can, telling your brain you're full. Without it, you can eat as much plain baked potatoes, plain bagels as you want and you'll still think you need to eat more - which is where the old diets, at least for me, failed. There, I had food on my mind all the time.

How difficult has it been? Well since I'm now self-employed, and work at home, I have more control over my food - I work next to the kitchen. If I'd had to stick to the canteen, which is stuffed full to the brim with low-fat sweet things, there's no way I could have done it. Eating out is fine, too - chicken or beef or fish with veggies. I have developed an (expensive) taste for sashimi, and sadly have been avoiding Indian or Thai - for the time being. I eat a huge amount of nuts - unsalted almonds, Brazils, walnuts - and if I'm trapped with nothing appropriate to eat I'll eat mini-sized cheeses. I knew I'd cracked it when I went with some friends to Devon. They spent the entire five-hour car journey eating Pringles and chocolate. I ate nuts. I knew I could do it.

Eight months later, I'm still eating according to Atkins principles, and although my weight fluctuates by a few pounds, I've still kept most of it off. I have, however, begun to get a bit fed up with the limitations of the Atkins diet, and have started occasionally to eat things like croissants and rice, or even desserts. Such episodes seem to activate my carb cravings, and I put on weight instantly, so I tend to go on a few days of the strict Atkins induction phase to get myself back on track. I am getting tired of eggs for breakfast, but do find that if I don't eat them, I have trouble getting through the morning. And I've started eating fruit again (forbidden in the strictest part of the diet - it's full of sugar, albeit natural) because it just seemed silly not to.

Would the Atkins work for everyone? Possibly not - I have definitely inherited some genetic tendency towards blood sugar metabolism difficulties, and so it works perfectly for me. Others of my friends complain it makes them exhausted when they follow it, and they just feel unwell. But I've come to realise that despite what the diet industry had us believing for years, everyone is different. And no diet will work for everyone. But I'm very, very happy that the Atkins diet has worked for me.

Was Dr Atkins right, despite all the warnings?

Dr Robert Atkins's book, Dr Atkins's New Diet Revolution has sold around 10 million copies worldwide. Its author, an American cardiologist, died last month, aged 72.

* The theory behind the diet is that carbohydrates encourage the body to produce insulin, which in turn causes fat. If carbs are avoided, the body starts to burn its own fat for fuel. This process is called ketosis.

* Dieters are advised to cut out carbohydrates such as bread, pasta and rice, but are free to indulge in as much protein and fat as they want.

* The diet has been heavily criticised by those who believe the prescribed diet to be dangerously unbalanced, and those who complain of side-effects such as headaches, nausea and bad breath.

* Clinical trials reported last week in the New England Journal of Medicine found that those on the Atkins diet lost twice as much weight as those on a low-fat diet and suggested that it could help combat diabetes and heart disease.