According to 6ABC Action News in Philadelphia, celebrities such as Madonna and Demi Moore have reportedly followed this "werewolf diet."
Howling at the moon is reportedly optional.
The diet is centered around the phases of the moon, and followers eat according to what phase the moon is in. The idea is that the moon influences how your body flushes toxins, just as it influences the ocean's tides.
The basic plan: On a new or full moon, you'll fast for 24 hours, only drinking water or fresh fruit and vegetable juices, Action News reports.
In the extended version, what you're supposed to eat and drink -- and when you're supposed to do it -- changes as the moon waxes and wanes.
You can supposedly lose two to six pounds during the fasting period, but experts tell Action News it's all water weight that will be gained back wants the fast ends.
Get more on this story, including additional diet details and a doctor's response, from our sister station, WPVI-TV.