Explaining the diet change, the rapper posted on his website Life and Times that he wanted a 'spiritual and physical cleanse', kick started by turning 44 in December.
The million dollar power couple are sticking to a 'plant-based' diet and cutting out processed foods and meat - but will stop in time to stuff their faces on a Christmas day feast.
We know what you're thinking - what's the point in food without sugar, meat and fat? But let chef Beyoncé change your mind...
The singer has been posting Instagram snaps of her healthy vegan meals, and they look pretty darn tasty.
Fans' reactions on Twitter however have been a mixed bag between...
1) 'I just could never do that - pass me the bacon'
2) 'Bey is Queen - her will shall be done'
Beyonce and Jay Z are going on a 22 day vegan challenge. I wouldn't even know where to start or how to shop if I decided to go vegan.— Tasha Deidre (@TashaDeidre) December 4, 2013
3) 'I can no longer support someone who makes me feel bad about my pizza addiction'
If you fancy a pre-Christmas cleanse but aren't convinced you can go fully vegan - you could always give the Eat Vegan Before 6 Diet a go.
No, we didn't just make that up.
Developed by food writer Mark Bittman, you just have to make sure two thirds of your day is spent eating vegan - then you can still go out for dinner guilt free in the evening. Score.
Upping your veggie intake will increase your Omega-3 levels, antioxidents and vitamins and reducing your dairy and meat eating ways will slash the amount of saturated fats in your system.
And if you start to falter, just think - what would Beyoncé do?
Penny for your thoughts. Tweet us @handbagcom
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