Beyoncé and Jay Z are embarking on a 22-day diet. The superstar couple decided to give veganism a try and will be eliminating all meat and animal products from their diet until Christmas, E! News reports. The rapper revealed the news in a blog post on Life + Times.

"Psychologists have said it takes 21 days to make or break a habit. On the 22nd day, you've found the way," he wrote. "On December 3, 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!"

The "Magna Carta" rapper said he got the idea from a friend and vegan who encouraged him to start eating plant-based meals for breakfast.

"It was surprisingly easier on me than I thought," he said.

So why now? Jay Z explained in the post that his reasoning for beginning the challenge one day before his birthday had a spiritual connection.

"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," he wrote. "It just feels right!"

He promised fans that he would continue to update them on his "spiritual and physical cleanse" but he's not exactly sure if he'll stick with the diet after the challenge ends.  

"I don't know what happens after Christmas. A semi-vegan, a full plant-based diet? Or just a spiritual and physical challenge? We'll see," he said adding that his wife, Beyoncé will also join him.

Veganism is said to be extremely popular in Hollywood. Ellen DeGeneres, Brad Pitt, Olivia Wilde and Alicia Silverstone are also vegans.

Wilde spoke about the challenges surrounding a plant-based diet to Ecorazzi in 2012. At first she started off as a vegetarian and later switched to veganism.

"I have been a vegetarian since I was like... 12," she said last year. "But [being vegan] has been something that, for the past four years, has been at times consistent, other times less so. It helps if you have the right support system."

She said her support system is actress and vegan Alicia Silverstone and credits her for introducing her to veganism while they were shooting a movie in Louisiana.

"We were shooting a movie called 'Butter' and we were in Northern Louisiana - where there is no vegetarian food - and she cooked the most incredible recipes from the Kind Diet for me," she said. "I have never looked or felt better in my life."

"[Being vegan] is not always easy and accessible," she added. "But it's a way of life and makes me as a person feel really good and physically look better. My skin was better, energy was better."