Hollywood embraces diet trends like Miley Cyrus embraces twerking on YouTube. Traveling across the pond, direct from England, there is a new diet that stars like Kelly Osbourne and Katy Perry are raving about: The Mushroom Diet, aka the M-Plan.

The Mushroom Diet promises to help women spot reduce, meaning: lose the rolls, keep the curves. The diet's promoters claim that women will lose weight everywhere except for their breasts.

Tanya Zuckerbrot, a registered dietitian in New York City is skeptical. "The diet is simply a low-calorie diet," she says. Swapping a cheeseburger for a portabella burger does save you around 173 calories and, compounded over the 14-day period the M-Plan recommends, and those are some serious calories saved. But, according to Zukerbrot, "Fat is fat and no diet can actually help you spot reduce."

Zuckerbrot explains that, "Mushrooms are an amazing food. 1 cup has only 25 calories and 2 grams of fiber. They are also a great source of potassium; 1 cup of mushrooms contains more potassium than a banana or a glass or orange juice." If you are going to pick a single food diet plan, the mushroom diet has some actual great health benefits, plus, you can eat every kind of mushroom. From Shiitake to Portobello, at least you're not stuck slurping cabbage soup all day.

Ultimately the question is, does the diet work? "I'm skeptical" says Zuckerbrot. "I'm sure you will lose weight, but the fact remains that no food in particular can create targeted weight loss. Whether its mushroom or steak, the laws of thermodynamics dictate, if you consume less calories, you will lose weight, just not everywhere but your breasts."