© Kred, PacificCoastNews

Johnson is the innocent and beautiful college student turned recent graduate, who falls for Dornan, the handsome copper-haired entrepreneur. His obsession with S&M is eventually revealed and he asks her to be his submissive lover. But that's the tame version of the erotic romantic story, of course.

The star is working hard to stay in shape for all her time in the Red Room of Pain, and it seems that she has adopted the latest Hollywood diet trend: juicing.

Johnson and director Sam Taylor-Johnson have been ordering juices from The Juice Box, an organic cold-pressed raw juice company based in Vancouver.

"They order the organic cold-press juices. They love them. They have a standing order for them," an insider exclusively told E! News, adding that the pair "are not doing a cleanse and are basically drinking a couple each day."

(E! and Universal Pictures are both part of the NBCUniversal family.)