Move over Dukan Diet. With swimsuit season inching ever closer, yet another "gimmicky" diet is making news. The 17-day diet, a new plan that's topping bestseller lists, claims dieters can lose as many as 12 pounds in the first 17 days."This diet is designed to produce quick results, not because it starves you down to size but because its carefully designed balance of food and exercise adjusts your body metabolically so that you burn fat, day in and day out," says the diet's creator, Dr. Michael Moreno, at ABC News. Here, a brief guide to the fad diet du jour:

How does the diet work?
It's divided into four cycles, each lasting 17 days, and based on the principle of "metabolic confusion." In the first phase, "accelerate," quick weight loss is the goal, and you consume just 1,200 calories per day. Dieters are allowed unlimited lean proteins and nonstarchy vegetables, and some fruit and low-fat yogurt. In the second phase, "activate," dieters alternate between low- and high-calorie days, with the goal of losing five to 10 pounds. The third phase, "achieve," concentrates on portion control. The fourth and final phase, "arrive," focuses on applying lessons from the earlier phases to establish lifelong healthy habits. Throughout the diet, no fruits or starches are allowed after 2 p.m. Exercise requirements begin with a daily 17-minute walk, and grow more intense.

Metabolic confusion? Come again?
Also known as "calorie shifting or cycled eating," it's the concept that by changing the way one eats or drinks every couple days or weeks, one can prevent metabolism from getting too static, and thus increase weight loss. "Everyone wants fast results and the calorie confusion of this plan burns fat, achieves weight loss results, and helps dieters avoid boredom," says Moreno.

Does metabolic confusion really work?
Many are skeptical. "There is no scientific evidence to support the efficacy of calorie cycling or its effect on metabolism," says Mary Hartley, a registered dietician with a masters in public health. Plus, studies show that those who maintain a healthy diet in the long term don't rely on low carb diets like this one.

But it's worked for some people, right?
Yes. While this diet plan is packed with gimmicks, it also suggests a number of healthy habits, like an emphasis on eating breakfast each day and a consistent but doable amount of exercise, says Karen Borsari in Shape. So "of course people have shed pounds," says Marissa Cevallos in the Los Angeles Times. The dramatic calorie reduction early in the diet is effective enough. "And it's not too surprising that people would lose weight on a diet that recommends eating fruits, vegetables, lean protein and yogurt, drinking plenty of water and getting lots of exercise." Plenty of diet and health websites espouse the same wisdom.

Sources: ABC News, Huffington Post, Yahoo!, WebMD, Fat Burner Review, Shape, Los Angeles Times