Obituary: Michel Montignac, Pioneer of glycemic index diet methods whose books sold in their thousands

Michel Montignac was the self-trained French diet promoter who wrote best-selling books and built a business based on the idea that losing weight depends on what you eat, not how much.

Montignac, who was overweight as young man, and came from a family with a history of obesity, was an executive for a pharmaceutical company in the 1970s when he began looking for ways to lose pounds.

Although he had no medical training, he used scientific papers to create a diet that divided carbohydrates into good or bad, depending on their glycemic index - the amount of glucose, a sugar, they release into the blood.

Thirty years later, the author of The South Beach Diet, Dr Arthur Agatston, adopted a similar approach.

Testing the idea on himself, Montignac lost more than 30 pounds in three months, according to his website, www.montignac.com.

Montignac contended that counting calories to lose weight is a "scientific swindle".

He argued that a "survival instinct" leads the body, after an initial weight loss, to store fat.

Instead, he proposed that dieters cut back sharply on foods known to raise blood sugar, and he developed rules detailing which foods may be eaten with others to aid digestion.

On that basis, potatoes, white bread, white rice, corn, refined flour, cornflakes and carrots are bad. They should be eliminated, Montignac said, because they contain starch that is converted into glucose.

Glucose prompts the pancreas to pump out large amounts of insulin, which drives blood sugar into the body's cells. When glucose is excessive, the body lays down fat.

In the good category are wholewheat bread, beans, lentils, wholewheat pasta, green vegetables, wild rice and dark chocolate with a cacao content of more than 65 per cent.

Montignac's theory was that although these foods also contain starch, their high fibre content slows its conversion into glucose so that less is infused into the cells at one time.

In 1986, Montignac published, at his own expense, Dine Out and Lose Weight, aimed particularly at business executives who eat out frequently.

It sold 550,000 copies in France. A year later, he published Eat Yourself Slim ... and Stay Slim! a layman's version that by 2005 had sold more than 16 million copies in 40 countries.

Over the years he wrote around 20 books on dieting and health, one of the better known recent publications being The French Diet, in which he explained why people from his home country were less likely to get fat than most other people.

Montignac also opened diet stores, spas and restaurants throughout France.

"All traditional methods of dieting have amounted to a myth as big as Communism, and like Communism, they are destined to collapse," Montignac said in a 1993 interview.

Despite Montignac's success, his method has had many critics.

"The diet is basically a delightful, joyous swindle," Dr Marian Afpfelbaum, a nutrition professor at the Bichat medical school in Paris, said in 1993.

Dr Jules Hirsch, director of the Laboratory of Human Behaviour and Metabolism at Rockefeller University in Manhattan, said that "almost every dietary possibility has been tried, with alterations in the amount of fat versus the amount of carbohydrates."

He added: "Interesting as these possibilities have been, the verdict over the decades seems to be that regardless of the components in the diet, the total caloric intake is the more important factor in prevention or treatment of obesity."

Michel Montignac, who lived in Juvigny, haute-Savoie in France, is survived by his daughter, Sybille, who is a dietician.