PREVIEW

The actress shared the details of the extremely strict regimen she stuck to in preparation for her role as Amy in the upcoming biographical movie Back to Black. "I had help to do it safely; I consulted a dietician and was being monitored," Marisa told Harper's Bazaar UK. And she admitted being surprised by how much the drastic weight loss assisted her in embodying the singer. "Feeling frailer and smaller helped - I hadn't understood, before, how much that affects your tempo," she added. Marisa, 27, went on to explain she found it harder to perform with the same energy as her weight crept downwards, which tied back to the ways Amy's own performances changed as well. "During her Frank (Amy's 2005 album) era, Amy is fast and loud and boisterous with her arms, her movements are big," Marisa explained. "Once I started to change, I realised that you can't physically make those same movements. It's uncomfortable to sit. You're tired, you're hungry, you're more exposed."

THIS VIDEO MUST NOT BE EDITED FOR LENGTH TO COMBINE WITH OTHER CONTENT