John, a 36-year-old from London, is discussing the foods his diet allows. Carrots perhaps? Or quinoa? “I'm very keen on a raw hare carcass,” he says. “Raw mallard is good too. So's raw tongue and raw organ meat. Ideally, it'll have been sitting around for three or four weeks and be really off. Some people like it when it's liquid mush but I prefer it really off, but still so you can stick a fork in it.”

If the Pineapple, Atkins and Cabbage Soup diets seemed extreme, then consider the fanatics worldwide following the latest allegedly detoxifying trend - the Primal Diet, an eating plan consisting of raw meat, eggs and dairy - preferably past their sell-by dates. The diet, the latest to hit Hollywood, was founded by Aajonus (pronounced oj-enus) Vonderplanitz, a 62-year-old nutritionist from California - and it can be only a matter of time before it's endorsed by a twig-thin starlet. The theory is that raw fats bind to the toxins in the body, which are then more readily transported out of the system.

At its most basic level adherents exist on 95 per cent raw meat, including chicken (made more palatable with a marinade of herbs and spices). When they eat out they can rely on culinary classics such as sashimi, steak tartare and beef carpaccio. The remaining 5 per cent is made up with vegetable juices and low-carbohydrate fruits, such as avocados. True aficionados, however, favour “high” meat (so called because of Vonderplanitz's claims that it inspires a natural high), with a small sideorder of rancid unpasteurised yoghurt and fermented vegetables.

“It took me a long time to try high meat because I was scared,” John says. “It does stink like hell and it tastes like an aged raw cheese. The first time I tried it I had to chase it down with a glass of mineral water and I did have a couple of days detoxing, with a bit of diarrhoea. But now my only regret is being squeamish for so long. I used to have all sorts of health problems but now I feel great. I've heard of a couple of people with parasites from it, but I've been doing it for seven years and I haven't died yet.”

John was right to be scared. “Advocating a diet that relies on eating raw meat is simply irresponsible and could be downright dangerous,” says Dr Andrew Wadge, the Food Standards Agency's chief scientist. “It is a simple fact that raw meat may contain harmful bacteria that can cause serious illness and even death. There are still around 500 deaths a year in the UK from food poisoning.”

But “high” primal diet followers say that the risks are worth it. Websites are filled with testimonials claiming that various ailments - including incurable cancers - were cured after a couple of months of rancid raw buffalo.

Vonderplanitz shrugs off any criticism, arguing that doctors have never observed the effects of his diet, while he has witnessed it “reverse 95 per cent of all diseases, while energy, mental clarity and emotional wellbeing are acquired within 30 days to two years”. He does, however, advocate eating rotting meat only if it is organic and free range, ideally grass-fed, and a period of preparing the body by eating fresh raw meat is advised.

A spokeswoman for the Centre for Human Nutrition Research in Cambridge says there has been no research into the possible benefits of eating raw or rotten meat, “because the health risk would be too great”.

But when it comes to squeezing into a bikini, it seems that some people will risk anything. “Fad diets like this are quick-fix solutions,” the spokeswoman says. “We think they'll solve all our problems, even though we know in the long term that they are not sustainable and have no real benefit.”

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