Transcript for Jay-Z and Beyonce's Three Week Vegan Diet
One of hollywood's most famous power couples is jumping on a trepddy diet bandwagon. Beyonce and jay z are on a three-week planet-based diet. How committed are they with beyonce wearing suede and fur the other day. That's a big no no. Reporter: Soup star couple jay z and beyonce are jumping on the band wagon. The holy grail artist who turned 44 on wednesday posted on his personal website that he and b are embarking on a 22-day challenge to go completely vegan. Or as I preper to called i, plant-based. They're notoriously private about their lives together. So it is a little unusual that they're being so public about what they're going to be eating. Reporter: He says this all began a few months back when a good friend and vegan challenged me to embrace a plant-based breakfast every day. That is marco bourgis. The mastermind behind this 22-day cleanse. His website inviting treersd take the 22-day charge with daily vegan menus. I met with a knnutritionist. Some people gain weight. Reporter: Why is hat? Some of it could be sweet poe day p potato fries. You need plenty of protein if you go vegan. It's about balance and knowledge. You want to make sure you're not getting the wrong food. Reporter: Calling it a spirit chu spiritual and viz caphysical cleanse, they will end it on christmas. He posts, best of luck and good health. If there was any doubt that this couple is probably the most famous couple in the world, the fact that we're intrigued by what they eat. I mean, you're famous. I don't ask you what you ate last night. I guarantee you, it wasn't interesting. We'll see if they hold up to this. Coming up here on "gma," jimmie johnson, paying homage to
This transcript has been automatically generated and may not be 100% accurate.