Is this the heir to Dr Atkins?

Pierre Dukan says he's found the secret of permanent weight loss - and millions of French dieters now follow his regime. He tells Lena Corner how it works

When Parisian nutritionist Dr Pierre Dukan introduced his diet to the French public 10 years ago, it was published by a small imprint with zero budget for a marketing campaign. By rights it should have dropped straight off the radar but news of the book spread by word of mouth and three years ago it finally made it's way into the bestseller lists. Now The Dukan Diet has shifted more than two million copies in France alone and another million worldwide. Celebrities such as Jennifer Lopez used it to lose their baby weight and this month, it's finally coming to the UK.

One reason for the book's success is Dukan's medical background. A doctor of 40 years standing, he had no interest in churning out a run-of-the-mill diet book. A GP and neurologist in Montparnasse, Paris, he specialised in treating paraplegic children. He knew nothing about weight loss or nutrition. His interest only began when his avid medical curiosity was kick-started by one of his patients.

"One of my regulars, who suffered badly from asthma, asked me to help him lose weight. I declined. But he begged me. He said, 'Put me on whatever diet you want, deprive me of whatever food you want, but let me eat meat.' I told him without hesitation to go away and eat all the non-fatty meat he liked, drink plenty of water and come back and see me in five days."

When the patient returned he'd lost 10lb. At first they thought the scales had broken. For Dukan it was an epiphany. He says: "That moment changed the course of my professional life forever." Dukan gave up neurology and enrolled at nutrition school and the seeds of his diet began to germinate.

Here, they taught him the only nutritionally correct way to lose weight was by calorie counting. Dukan didn't believe it. He says. "We are not programmed biologically to count calories, we are programmed to eat what we want. I decided to make a diet which had nothing to do with calories."

Dukan was horrified by the number of diets that focus on weight loss but fail to deliver on maintaining that loss. So he set about inventing a diet that consists of four stages – two to lose the weight and two for maintaining the weight. Dukan calls the first phase the "attack" period, during which you are allowed to eat as much as you like from a list of 72 high-protein foods – lean meat, fish and a few non-fat dairy products. After that you move to the "cruise" stage in which 28 vegetables are added. "One of the important things is you can eat as much as you want," says Dukan. "You feel you aren't sacrificing anything."

The cruise stage is finished around the moment you hit your "true weight". "This is the weight you can reach and maintain at the same time," he says. "We all have a weight we can reach but the weight we can maintain is very different."

To work out your true weight (Dukandiet.co.uk) Dukan has invented a calculation that utilises 11 different parameters including how many children you have had and how quickly you lose weight. A couple of minutes spent jabbing in answers and it tells me my true weight is 9st 12lb, which, if I follow the plan, I will achieve by the end of July. What's interesting is that even though I would hit my true weight in 35 days, it doesn't count until I have spent 47 days on the third "consolidation" stage. "This is a very important phase," says Dukan. "It's the phase that, when you finish, you are back in real life."

The high protein content in the attack phase of the diet has led many to confuse Dukan's diet with Atkins'. Dukan says: "Atkins was a revolution. He changed the thinking. He said all calories are not the same: 100 from sugar are very different to 100 from fish. He was a genius, but made one mistake – he said you can eat as much fat as you like. This works when you are losing weight but makes it impossible to stabilise and is also bad for the heart."

Dukan claims to have tried more than 200 diets. The only other one he thinks worthy of a mention is WeightWatchers, not for its points/calorie-counting system, but for its recognition that dieters benefit from some sort of group support. Dukan has embraced the internet as his support tool and spends an hour a day doing a live forum and has a team of six nutritionists answering people's queries. Currently he has about 100,000 subscribers in France paying about 10 euros a month for the service. It has spawned a huge online following and as well as various forums and blogs there is a big Facebook presence crammed with people sharing recipes and stories of weight loss or weekend lapses.

One of the glaring drawbacks to Dukan's diet is that it's weak for vegetarians. During the attack phase there's little they can eat apart from non-fat cottage cheese, tofu or yoghurt. There's also the issue of bad breath during the early stages. "Bad breath means you are losing weight," says Dukan. "You have that with any diet. You can always have some chewing gum – sugar free of course."

One of the best things about his diet is its common-sense approach. During the third stage, for example, he has built in two "celebration" meals a week in which you can eat what you like and drink alcohol. It also reintroduces bread and cheese. And he's worked out a way he believes the weight will stay off, with a fourth stage which involves eating what you like, but sticking to protein for one day a week.

"This diet has become my life and my mission," he says. "I have everything I want: a wife, two children, a profession, money. Now I want only one thing, to make my diet available to the world. We have a massive obesity problem which I am hoping to address. It's ambitious but I live for that. I think it's possible."

The Dukan Diet by Dr Pierre Dukan (Hodder & Stoughton £12.99)

The diet's four phases

Attack

Otherwise known as the "pure protein" phase, this first stage is designed to dramatically kickstart weight-loss. It lasts between two and seven days, during which you are allowed to eat as much as you like from a list of 72 high-protein foods, specifically lean meat, fish and a few non-fat dairy products.

Cruise

Alternate a pure protein day with a day of eating protein and vegetables. The length of time you need to do this for is calculated per kilo per week. So if you want to lose 10 kilos, you would do this phase for 10 weeks.

Consolidation

You're allowed two pieces of fruit a day, two large pieces of bread as well as 40g of cheese. Best of all, you're allowed two "celebration" meals a week in which you can have alcohol, chocolate, dessert and any other food you may have been craving.

Stablisation

Finally here you can go back to eating what you want six days out of seven, but for one day a week you must return to the attack stage and eat nothing but high-protein food. "Protein Thursday" has really taken off in France. Also you are obliged to consume a daily dose of oat bran and "live your life as if lifts and escalators did not exist".