Beyoncé and Jay Z have challenged themselves to follow a strict vegan diet until Christmas Day.

The superstar couple have revealed plans to get healthy before they indulge over the festive season by banning meat and dairy from their diet.

Jay Z told fans about their food plans yesterday (December 3) on the eve of his 44th birthday.

The rapper wrote on his website: "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!!

"This all began a few months back when a good friend and vegan challenged me to embrace a 'plant-based breakfast' everyday.

"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 . . . It just feels right!"

The couple was spotted eating at vegan restaurant in California shortly after Jay Z made the post on his website.