This new diet book says you can eat whatever you want and lose weight, but our expert is skeptical.

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There are lots of reasons why America is the fattest nation in the world. One may be that we've created this 24-hour eating culture where we're spending most of our days grazing on too many extra calories that we're simply not burning off. Or at least that's the premise behind David Zinczenko's latest book The 8-Hour Diet, which offers the perfect semi-scandalous solution.

In a nutshell, the former Men's Health editor and co-author of other bestsellers, including The Abs Diet and Eat This, Not That! series, suggests cutting back eating hours to just eight for up to three days a week for guaranteed weight-loss results. What you eat within those eight hours is entirely up to you. So if you wanna binge on the whole Frito-Lay line, by all means, print out this story and use the paper to wipe your greasy fingers between bags.

The catch-there always is one-is that once your pig-out period ends, you have to fast for the remaining 16 hours. This, in turn, will supposedly give your body the break it needs to digest and start burning fat for fuel. Hence, why the diet claims you can lose up to 2 and a half pounds a week. Zinczenko himself claimed he dropped seven pounds in just 10 days on the diet in a recent Today Show interview. "Without even trying," he emphasized to a skeptical Matt Lauer, who retorted with "You say people can lose 20 pounds in six weeks, according to you."

Lauer isn't the only one casting a shadow of a doubt. Tanya Zuckerbrot, R.D., author of The Miracle Carb Diet, sees four big downfalls of this plan.

1. It Builds Bad Habits

Just when you've completely abandoned the idea of "eating with abandon," this book comes along and says, go ahead, have that second pizza slice and yes, you do want fries with that. As long as you can cram it all into that eight-hour window, you're free to view the world as one big menu-and in the long run, that could promote weight gain. "Anything that you do temporarily will garner positive results, but once you get off the plan, you're just left with these bad binging habits," Zuckerbrot says. "It would be better to teach people about how their body works, what vitamins and minerals they need, and how to understand portion control for long-term results." To that point, one could argue that Zinczenko does list eight power foods, however, his diet plan would also support choosing Nutella-stuffed French toast over such "power" foods, like yogurt, for breakfast, if that's what you're in the mood for.

2. It Ruins a Good Health Record

Though The 8-Hour Diet suggests it can help prevent disease, citing scientific studies that show how fasting has lowered the risk of developing diabetes and coronary disease, Zuckerbrot believes it might encourage the opposite effect. "Consuming large amounts of foods high in calories and saturated fat such as pizza, rib-eye steaks, and burgers may not only pack on pounds, but also increase your risk for developing chronic diseases such as heart disease and diabetes," she says.

3. It Fosters a Horrible Mood

If you've ever skipped lunch on a busy day, you know exactly what we're talking about. Zuckerbrot puts a finer point on it: "After just four hours of fasting, your sugars begin to drop and you start to feel weak, tired, shaky and cranky-that's what we call reactive hypoglycemia. All those feelings tend to drive people to grab whatever food is available, like potato chips or cookies on the counter, or overeat at the next meal." Which is why Zuckerbrot encourages snacking between meals to keep folks from treating the breadbasket like a trough.

4. It Messes with Your Social Life 

Say you follow Zinczenko's recommended plan of three days a week. If you're eight hours of eating fall between 10 a.m. and 6 p.m., you'll have to cancel your dinner date with friends or awkwardly sip water across the table from your colleagues at after-work drinks. Or worse, you might have to move around your entire social calendar to accommodate your weird eating schedule. "It's just not a sustainable lifestyle," Zuckerbrot warns. "We need to learn how to be more disciplined and have a few bites without over-doing it."

The f-word for weight loss isn't feast, fast, or famine, Zuckerbrot says-it's fiber. Fill up on the good stuff-along with protein-every three to four hours to stay energized and maintain your blood sugar levels all day long. A recent study in the Journal of the American Medical Association found that eating a high-fiber diet also helps to take off the fat and keep it off. Young adults who consumed 21 grams of fiber daily compared to the recommended 25 grams saw benefits, so aim for 25 but don't worry too much if you fall a little short, Zuckerbrot says.