‘FastDiet’ craze hits U.S. from Britain

Blimey - a British diet craze seems to be successfully invading American shores.

The FastDiet, out less than a week in the United States, is already the No. 1 book at Amazon.com.

That's on the heels of being the top seller for weeks in Britain, despite being published just in January.

It's based on the findings by physician-journalist Michael Mosley that people can benefit from intermittent deprivation, and that occasional semi-starvation is a lot more tolerable than weeks or months of unrelenting self-denial.

"You just limit your calorie intake for two nonconsecutive days each week - 500 calories for women, 600 for men. You'll lose weight quickly and effortlessly," claims a promo for the book, cowritten by Mimi Spencer.

Fast for two days, eat normally for five each week - that's why it has also been dubbed the 5:2 Diet.

Mosley developed the plan through "self-experimentation," because he wasn't feeling well last year, he told the New York Times, which noted he's been called the British version of Sanjay Gupta, CNN's chief medical correspondent.

That led to a BBC documentary about his quest and the results titled Eat, Fast and Live Longer, which was viewed by several million people.

Not only did he lose 20 pounds in nine weeks, but cholesterol and blood-sugar levels dropped, while his sense of energy increased.

According to an ABC News report on Mosley's combining "feast and famine," "researchers across the U.S. have been finding astonishing results from severe calorie restriction - decreased cancer risk, increased life expectancy, even improved brain function."

And weight-loss testimonials abound.

ABC quoted a woman named Tara McLaughlin that she lost 36 pounds.

In less than three weeks in January, Guardian food writer Hugh Fearnley-Whittingstall, wrote that he'd already lost eight pounds "with my strictly non-snacking version ... and I find the whole thing rather exhilarating."

"I believe in this fasting thing, I really do," he wrote. ". . . I feel I might just be part of a health revolution."

Co-author Mimi Spencer, who supplies the practical tips portion of the book, including meal planning, lost 20 pounds over four months.

Twice a week, the "glamorous British journalist . . . follows the same ultra-restrictive diet - low-sugar muesli, a splash of 1 percent milk and a couple of strawberries at breakfast, an apple for lunch and, for dinner, arugula salad with a slice of chicken or tuna," according to the New York Post.

Men reportedly feel more comfortable with this diet, compared to traditional long-term calorie-counting plans.

Mosley argues that this style of eating is quite natural, since for most of history, people experienced alternating periods of consumption and deprivation.

Beware, ABC warns, experts say it's not a diet for anyone under 20, for pregnant women, or people with eating disorders.

Britain's National Health Service cautions that the safety and efficacy of the diet has yet to be properly tested. Further, anecdotal reports suggest intermittent fasting might have such side-effects as anxiety, irritability, dehydration, drowsiness, sleep problems and even bad breath.

Generally, medical experts advise everyone to have a conversation with a physician, and even a physical exam, before undertaking any usual diet or strenuous exercise plan.