The alarm has sounded: Beyonce and Jay Z are working on a new joint project -- veganism for the next three weeks.

The "Holy Grail" rapper announced the new plan to take on a plant-based diet on his website, Life + Times.

"Psychologists have said it takes 21 days to make or break a habit. On the 22nd day, you've found the way," Jay Z wrote. "On December 3rd, one day before my 44th birthday, I will embark on a 22 Days challenge to go completely vegan, or as I prefer to call it, plant-based!" he write.

"This all began a few months back when a good friend and vegan challenged me to embrace a 'plant-based breakfast' everyday. It was surprisingly easier on me than I thought..."

Sparking the idea was Marco Borges, an exercise physiologist and founder of 22 Days Nutrition, a vegan, organic, and gluten-free lifestyle company.

"There's something spiritual to me about it being my 44th birthday and the serendipity behind the number of days in this challenge; 22 (2+2=4) coupled with the fact that the challenge ends on Christmas day," Jay Z wrote. "It just feels right!"

"So you can call it a spiritual and physical cleanse. I will post my progress...Any professional vegans out there that have any great food spots, please help out!"

"P.S.," he added, "B is also joining me."