Mulligan, 30, was able to adhere to her dietary restrictions in the weeks leading up to the scene, but she went overboard after the shoot and ended up putting weight on, reported Contactmusic.
"The Suffragettes, many of them went on a hunger strike and were force-fed, which is something I didn't know and so I went on a Suffragette force-feeding diet.
"It was successful for the scene. Up until I shot it, I was eating, like, cottage cheese and mackerel and it was good and I did it for, like, six weeks and we shot the scene and then I needed to stay kind of gaunt looking, but not anything too drastic.