Will the Dukan Diet lose its attraction? "There is nothing unhealthy in educating youngsters about nutrition," Dukan said, but the College of Physicians views it as dangerous advice to children and a breach of medical ethics. Dukan is certainly not the only Frenchman to export dubious dietary fads to this country. William the Conqueror is said to have been England's fattest monarch. He made Henry VIII look like Victoria Beckham. In 1087, King Philip I of France described him as looking like a pregnant woman; he was too fat to ride a horse. Accounts vary as to the precise details of his fat-fighting diet. Some say he consumed nothing but alcohol; others that he entered an early weight-loss clinic near Rouen and went on to a regime of herbs and medicines. Either way, he slimmed down enough to get on to a horse again but to no good effect. Fighting the French at the Battle of Mantes, he was thrown against the pommel of his saddle and his intestine exploded, killing him. Nor is celebrity slimming a new phenomenon. Lord Byron described himself as having a "morbid propensity to fatten." At Cambridge he subsisted on biscuits and soda water or potatoes dressed in vinegar and wore thick-layered clothing to sweat off the pounds. He lost over five stone. Later, living near Lake Geneva, he lived on a slice of bread and cup of tea for breakfast, a light vegetable dinner and drank seltzer with a touch of wine in it. By the age of 24 he had starved himself into ill-health. Decades after the poet's death, in words that foreshadow many a modern health warning, an eminent doctor said: "Our young ladies live all their growing girlhood in semi-starvation," in fear of "incurring the horror of disciples of Lord Byron." The pilgrimage for moral, spiritual and physical health - often regarded as going hand in hand - gathered strength in the 19th century. Among the pioneers was John Harvey Kellogg (father of the cornflake) at whose Battle Creek Sanitarium in Michigan only whole grains, fruits, nuts and vegetables were served; he also recommended daily yoghurt enemas and discouraged sexual intercourse. Another American, Horace Fletcher, thought the road to dietary salvation lay in chewing. In a nostrum that many British people of a certain age will have had handed down to them in reduced form, Fletcher said that food should be chewed 32 times, or about 100 times a minute, before swallowing. "Nature will castigate those who don't masticate," he said. Franz Kafka was a keen adherent, though it seems to have done little to encourage a feeling of well-being. In 1863 William Banting, a once-obese English undertaker, wrote a booklet entitled Letter On Corpulence - possibly the first modern diet book. He advocated limiting the intake of easily digestible carbohydrates. He was attacked for it, but his book became enormously successful. So popular was his regime that people asked one another "do you bant?" People do not quite ask each other "do you Dukan? Did you Atkins? Did you Scarsdale? Did you Mayo? Did You Hay? Did you Cabbage Soup? Did you GI? But well they might. Millions do and have, and plenty have tried most of them, as well as a multitude of others. All of them "bant" - nobody has a good word to say for carbohydrates. The Scarsdale Diet - a New York Times bestseller in 1980 - was very strict. It advocated grapefruit for breakfast, fruits, vegetables and lean animal fats and offered appetite suppressants. It worked fast but maybe not for long. Its creator, Dr Herman Tarnower, became even more famous in death. He was murdered by his long-term mistress, the headmistress of a fashionable girls" school. A feature film followed. The Atkins diet majored in protein and wasn't frightened of consuming fat. Like many of the others, it started with a blitz then moved into what was intended to be a more sustainable regime. Many swore by it as the weight fell off; most of them will have long forgotten it when the weight piled back on later. Dr Atkins, who had been his own best salesman in life, became his own worst salesman in death. Aged 72, he slipped on an icy pavement in New York and sustained fatal injuries. Rumours abounded that he had been the victim of his own diet. True or not, the damage was done and the diet has had a much-diminished afterlife. Prominent among Atkins's British critics was Audrey Eyton, author of the F-Plan diet, apostle of high fibre as well as limited calories. It is less starry, less hyped and less sensational than the offerings of US and French doctors - starting with Dr Hay and his Hay diet, which involved separating food groups into alkaline, acidic and neutral and keeping them apart. The F-plan diet is also less open to medical criticism. Like many diets, including the Cabbage Soup diet, it is likely to give rise to excessive flatulence. But if you're desperate to lose weight, what's a little flatulence between friends? The Dukan Diet purports to offer long-term weight loss. The first short "attack" phase that gave Carole Middleton and a trillion others a dramatic instant drop is followed by a gentler "cruise" phase of protein and vegetables, then "consolidation" and "stabilisation," which should see them slimmer for the rest of their days. If only! However Dr Dukan fares with the French medical establishment and however briefly his diet remains the plat (or non-plat) du jour, one thing is certain: another new, more-magical-than-ever, more celebrity-certified fad diet isn't far behind. And however demanding it is, however impossible to maintain and however many health warnings it attracts, millions will swallow it.