France's medical order has sanctioned nutritionist Pierre Dukan, whose high-protein diet has seen him sell millions of books and win over a slew of famous followers, for having prescribed a slimming drug linked to hundreds of deaths.
Dukan, whose diet was reportedly used by the Middleton family ahead of Kate's 2011 wedding to Britain's Prince William, was sanctioned for having prescribed the anti-diabetes drug Mediator to a female patient in 1971, his lawyer Edouard de Lamaze said.
The Paris region branch of the French Order of Doctors suspended Dukan's medical license for eight days for the "breach of ethical duties" and ordered him to pay 6,000 euros ($7,700) to the patient, who subsequently developed heart problems.
Dukan was also sanctioned for having made "grossly misleading assertions" that he had only prescribed the drug once, when medical records showed he had actually done so five times.
Lamaze said the eight-day license suspension was purely symbolic because 72-year Dukan was no longer a practicing doctor.
The lawyer said he was appealing the decision and accused the medical order of carrying out a vendetta against his client.
Dukan is facing further disciplinary action after medical orders accused him last year of breaking professional rules by proposing that high school students be awarded extra marks if they manage to maintain an acceptable body weight.
Mediator, which reduces hunger pangs, was widely used as a slimming aid in France until it was pulled from the market in 2009 after evidence emerged of hundreds of deaths caused by damage to heart valves.
A study last year said the drug had probably caused at least 1,300 deaths before being withdrawn.