You've heard of the Scarsdale diet, the South Beach diet, and, of course, the almighty Atkins. But if you're tired of counting carbs and fats, why not just give up eating altogether?

That's the crux of the latest weight-loss fad: The Fast Diet. Dr. Michael Mosley of Britain has created a semi-starved army with his best-selling book of the same title. Also known as the 5:2 Diet, the gist is that you eat whatever you want five days a week, and then the other two days, you "fast" by consuming a quarter of your normal daily allotment of calories.

The theory is that you'll be "starving long enough to convince your body to start feeding off your fat stores, but not so long that it slows down your metabolism." Mosley says it's only the "least bit painful," and to treat those two days as "just a break from your normal routine." Crazy as it sounds, The Fast Diet is flying off shelves, and true-believers are singing its praises. Hugh Fearnley-Whittingstall at The Guardian writes that he "finds the whole thing rather exhilarating" and that he "might just be part of a health revolution."

Mosley also claims that intermittent fasting carries benefits that other diets don't. He tells the Huffington Post that "on a standard diet you lose about 75 percent fat, 25 percent muscle," but on the Fast Diet "it's between 85 and 100 percent fat." Mosley also tells The Boston Globe that the body enters "repair mode" when it's fasting and that "a lot of cellular repair takes place in between meals." The onset of dementia may even be delayed through intermittent fasting, Mosley says, though studies supporting this claim have only been conducted on mice.

Of course, not everyone is jumping on the hungry bandwagon of Fast Diet devotees. The U.K. National Health Service has created a site to qualify the benefits and stress the potential downsides of going 5:2. You'd think that you wouldn't need to tell people that dehydration, anxiety, and irritability are all potential side effects of essentially not eating for two days a week, but then again, you probably would also think a disclaimer that intermittent fasting "may not be suitable for pregnant women" would be unnecessary. Unsurprisingly, the NHS is highly skeptical of the purported long-term benefits of the Fast Diet, and is loathe to endorse it as a healthy means to weight loss.

There's also the practical question of how you define eating "normally" the other five days. Mosley cautions: When you're not fasting, "don't pig out, don't bury your face in the ice cream, but if you occasionally go out for a burger that's fine." That still sounds deceptively diet-y to me. You're still supposed to eat healthfully (again, what exactly that means is not abundantly clear) on the five days. So even if you suffer through your two days of hunger pains, it's not exactly going to be a gala of gluttony on the other five.