Diet guru Pierre Dukan 'lied to patients about pill linked to hundreds of deaths'
Dr Dukan, 71, whose protein-rich regime is said to have helped the Duchess of Cambridge fit into her wedding dress, was already facing disciplinary action over proposals to award extra marks to schoolchildren who lose weight.
He is appealing the ruling.
The eight-day ban is purely symbolic as Dr Dukan is no longer a practising GP; he voluntarily struck himself off the medical register last year. But it is another blow to the image of the celebrity nutritionist following a string of setbacks.
France's medical board found Dr Dukan guilty of a "breach of ethical regulations" after he prescribed Mediator – a drug estimated to have caused up to 1,800 deaths in France – on five separate occasions and then lied about it.
He was also ordered to pay 6,000 euros (£5,190) in damages to a former patient who developed heart problems in the early 1970s to whom he prescribed Mediator, even though the drug was only intended to treat diabetes.
The board said he had been dishonest, as he had in fact prescribed the drug as a weight-loss pill.
"In resorting to untruthful assertions, Dr Dukan displayed behaviour which lacks probity and discredits the profession," said the medical board in its ruling.
Mediator has been at the centre of a medical scandal in France since it was withdrawn from the market in 2009 after evidence emerged that it damaged heart valves, causing scores of fatalities.
Jacques Servier, 90, the founder of the Servier biopharmaceutical company which produced the drug, is due to go on trial in Nanterre, France, next year for "aggravated fraud". He stands accused of concealing the harmful effects of the drug's main active ingredient.
Mediator was never authorised in the UK or US.
The Dukan diet, launched in 2000 in France, has turned into a global success and boasts a host of celebrity followers, including Jennifer Lopez, supermodel Gisele Bundchen, and Welsh singer Katherine Jenkins.
Food experts have warned the regime is a 'health hazard' due to its very low vegetable and carbohydrate intake, while the British Dietetic Association voted it "the worst celebrity diet of 2011".
Last year, France's College of Physicians filed a complaint against Dr Dukan for breaching their code of ethics by suggesting pupils should be awarded higher grades if they manage to keep slim.
In a book out last year, he proposed creating a so-called "ideal weight" option for A' level equivalent students in their final year exams, under which they would earn extra points for keeping slim.
The French College of Physicians warned the proposal could prove harmful for pupils already suffering from obesity or anorexia.