Britain is bingeing on the Dukan Diet. With over a million books sold in the UK, and a million subscribers to Pierre Dukan's website, we have fallen for the French doctor's high-protein, low-fat, low-carbohydrate plan with a gusto not witnessed since the Atkins diet. Why? According to Dukan there are two key reasons: first, it works and, second, Carole Middleton.
In almost every interview he has given in the last 18 months, Dukan has mentioned Kate Middleton's mother. The press release for his new recipe book says the diet was "lauded for helping Carole Middleton get in shape" for last year's Royal Wedding and in almost every article about the weight loss plan she is cited as the cause of our devotion to it.
But all we know for sure is that Mrs Middleton was on it for four days. In October 2010 she told a journalist she had lost "four pounds in four days" on the diet, which is a lifelong plan that takes weeks, often months, to reach one's desired weight. Beyond those four days, how does Dukan know she follows it?
"I sent her my book," he says, chocolatey eyes twinkling against his olive skin and whitening hair.
Have you spoken to her about it?
"No, never," he admits. When I contact Mrs Middleton's publicist she refuses to confirm whether her client is or was a Dukan follower.
But that one quote about four pounds is enough to fuel both the explosion of interest and unsubstantiated stories in several newspapers that Kate Middleton also used the diet. The wildfire buzz is ablaze across 50 countries, with international book sales exceeding 11 million, and public figures from Jennifer Lopez to Francois Hollande, caught in the frenzy. The French president has lost 17 kilos on the plan, according to Dukan.
The invention of the strict, protein-rich weight loss programme has become dieting lore. The Algerian-born Dukan originally trained as a neurologist and was practising as a GP in Paris in the early 1970s when a dieting patient refused to cut out meat. Dukan advised a diet of lean meat and lots of water which led to the patient losing 5kg in five days – now known as the "attack" phase of the diet.
In 2000 his findings spawned his first book under the title 'Je Ne Sais Pas Maigrir' ("I Don't Know How to Lose Weight") – later published in English as The Dukan Diet. A series of books have followed including The Dukan Diet Recipe Book and Mon Secret Minceur et Santé: Le Miracle du son d'Avoine ("My Slimming and Health Secret: The Miracle of Oat Bran"), which is not available in English.
But 12 years after the Dukan Diet was first published in France, the 70-year-old's motherland has kicked back. Hard. In January, in an open letter to Hollande, Dukan recommended that pupils should be awarded higher marks in exams if they remained below a certain weight. A public outcry ensued along with a complaint by the French College of Physicians, claiming he was in breach of the medical ethics code. In April, amid the disciplinary procedure, Dukan asked for his name to be removed from the medical register. Did he do this to avoid it being taken off forcibly?
"Yeah, it's true," he says. "Because if you are no longer inside [the profession] they cannot condemn you. I wanted to be free with my words."
Does he still stand by his controversial suggestions?
"Yes," he says with a rather Gallic shrug. "I'd like to introduce it for all the teenagers in my country and all around the world. Sixteen per cent of the [French] population become overweight [during their last two years at school]. I thought, 'How can that be prevented?' Everyone knows that with incentive there is success."
But do you not understand why people are so upset?
"Of course. It was a misunderstanding – people spoke about discrimination but I didn't say discrimination. It was a good idea. I was convinced."
He was also convinced that his fellow French diet guru Dr Jean-Michel Cohen was guilty of libelling him by telling a magazine the Dukan Diet "leads to serious health problems in some patients such as a strong rise in cholesterol, cardiovascular problems and breast cancer". The court disagreed, instead fining Dukan €3,000 in July for "abusive procedure".
In the first stage of the diet, which lasts from two to seven days, only lean protein is eaten. Specific vegetables are then added until the dieter loses all the weight, with carbohydrates and fat reintroduced selectively in the third phase, which also includes a protein-only day every Thursday.
Does Dukan eschew all non-protein food once a week? "Only when I put on weight," he says.
Dr Cohen's is far from a lone voice. Last year the British Dietetic Association described it as one of the five worst diets, as "there is absolutely no solid science behind this at all".
Regardless of his detractors Dukan's business is today worth more than £80m despite reported side effects of the diet caused by the body burning its own fat including bad breath.
A survey in Le Journal des Femmes found that 80 per cent regained the weight after four years. "If you put on weight it's not by chance," he says. "You put on weight because you eat compulsively. It's life. I see people five years after [losing weight] and they say, 'I got divorced, my mother died, suddenly it wasn't a priority so I ate.'"
Do I need to lose weight? The diet guru looks me up and down and gives a rather surprising answer: "No."
It is surprising not because I am overweight – in fact I'm slim, slimmer than Dukan – but because the day before our meeting he emailed (or, to be precise, his website's automated email signed by him) to say I need to lose 2st 7lbs. When you subscribe to the (£1-a-week) site, you are asked a series of questions – height, weight, previous highest and lowest weights, history of weight gain within the family, and the weight you wish to be – which triggers an email from Dukan.
This contains your "true weight" - the weight you should be according to his calculations. In my case, despite being a 5' 9" 35-year-old man with a 32-inch waist, and a healthy 12 stone, the email tells me my "true weight" is 9st 7lbs. I haven't been this sleight since I was 16, when I looked like a skinny little boy.
"You must have made a mistake," he replies when I challenge him about this "true weight". No I haven't, I say and explain: I put in the correct physical and historical details and replied to the question about my desired weight "6st 5lbs".
This is, of course, a ridiculously dangerous goal. But it is not absurd to someone with an eating disorder or to the one per cent who suffer from body dysmorphia. And yet the goal of the subscriber is included in the calculation of their "true weight".
"Ordinary people don't cheat," he replies, testily. "You tried this because you are a journalist."
Do you not see the danger in a system that incorporates any weight target no matter how warped?
"Yes but [a subscriber's] dream weight is only one [criteria]."
With 10 other factors taken into consideration in the true weight, he is unconcerned. He also seems unconvinced that people with eating disorders might be accessing his system. "The problem is only with people who are very, very young and if they want to be in fashion and be very thin – why not? If it doesn't disturb their health."
As he leaves, his publicist hands me a Dukan goodie bag containing the new cookbook, the original diet book, and two inexplicable items: shower gel and deodorant. I'm left wondering whether he thinks fat people stink or journalists.
Paleolithic On this latest diet craze, followers must simply ask themselves: what would a caveman eat? That means no Big Macs or Krispy Kreme, and anything that even remotely resembles a carbohydrate.
Atkins In 1972, Robert Atkins published his first diet manual, which advocated limiting carbohydrates in favour of protein and fats. The diet took off in the earlier part of this century, and in 2004 a survey showed one in 11 Americans claimed they were on a low-carb diet.
Cabbage soup diet Thought to have originated in the 80s, the promise of losing 10lbs in a week ensured this diet's ongoing popularity. The meal plan is extremely limited: you can have as much soup as you want, but very little else. Critics say most of the weight loss is water rather than fat.
Master cleanse Beyoncé lost 20lbs in two weeks on the master cleanse, resulting in renewed interest for this crash diet from the 1950s. Followers may only consume a mixture of hot water, lemon juice, cayenne pepper and maple syrup.
Macrobiotic diet Endorsed by the likes of Gwyneth Paltrow and Madonna. Followers must swap processed foods, meats and dairy for wheatgrass juice and miso soup. The diet has been praised for its health benefits, but is not recommended for children.