Amy Frankel wanted to lose weight, so she tried the Overnight Diet, a new rapid weight-loss plan that claims you can actually lose weight while you sleep.

Frankel, a 42-year-old mother of one from Wayland, Mass., said she literally lost weight overnight, and during the course of the diet went from 174 pounds to 125 pounds.

"You are … burning calories and losing weight and you are not starving yourself and you're not ever feeling deprived. It wasn't difficult," said Frankel, who said she went from wearing size 10 and 12 to a size 4 in about a year of doing the diet, which she's now adopted as a way of life.

Dr. Caroline Apovian, an obesity doctor and the author of the new book, " The Overnight Diet," explained the regimen. Users do six days of a high protein diet and one day of a liquid diet. That, combined with sleep, equals weight loss, she claims.

"You can lose up to two pounds overnight. And then for the six days, you can lose up to nine pounds in one week after the first week," said Apovian, an associate professor of medicine and pediatrics at Boston University School of Medicine and the director of nutrition and weight management at Boston Medical Center.

"That first night, you go to sleep, you sleep your eight hours, you are down two pounds," she said. "If you continue to get enough sleep every night, you won't get those hunger pangs. The hunger pangs come from lack of sleep, which induces the hunger hormone to get secreted from your gut."

Apovian, who is also the director of clinical research at the Obesity Research Center of Boston Medical Center, said exercise is not required for users of this plan.

While typically, 25 percent of people who go on any diet actually lose weight and keep it off, Apovian said that in her clinic, that number rises to 50 percent.

Keith Ayoob of the Albert Einstein College of Medicine in New York said it was possible to lose two pounds overnight, but added: "It won't be fat. It'll be mostly water. Because there's no how, no way you're going to lose two pounds of body fat overnight."

"In order to lose two pounds of body fat overnight you'd have to burn up about six or seven thousand calories and there's just no way to do that by sleeping," said Ayoob, director of the nutrition clinic at the college's Rose F. Kennedy Center

"You know, you've got to actually expend that or cut back on your intake. And it takes longer than overnight to do that," he said.

Some are skeptical of the diet's claims of so much weight loss so quickly.

Apovian acknowledges that the first two pounds lost on her diet are mostly water weight and salt weight, but says it provides the incentive for a high protein diet and more weight loss.