Method acting is one way that actors and actresses get into character. This approach is considered one of the best in Hollywood. However, it takes a lot of off-screen preparation. It typically requires actors and actresses to transform themselves physically for roles. They will develop the same mannerisms and body language and some will even lose a considerable amount of weight to really get into the character. According to Lee Strasberg, “Method acting is what all actors have always done whenever they acted well.” That being said, let’s take a look at some of the most extreme method actors and actresses!

7. Michelle Williams

To play Marilyn Monroe in My Week with Marilyn, Michelle Williams immersed herself in research. She read books about her, read the books that the icon liked to read, engulfed herself in books on method acting, and carried recordings of the actress’ voice on her iPod. She also watched a lot of Monroe’s movies.

“I started with The Prince and the Showgirl,” she told the National Post. “I started watching that movie while my daughter was in school, absorbing as much as I could, pausing it, trying to emulate what I had seen, made a lot of mistakes, completely clueless, and then, one day, things started to come together.”

Williams didn’t stop there. She also rigged herself up in costumes that Monroe would wear, which included a tight dress, a push-up bra and high heels, and did her best to imitate her famous slinky walk. To do this, she tied her knees together.

6. Natalie Portman

Natalie Portman didn’t intend to go method in Black Swan.  However, that is what she ended up doing. To prepare for the role, she trained for five hours a day for six months prior to filming, doing ballet, cross-training, and swimming. Just like her character in the film, she barely ate and lost 20 pounds a result. “I was barely eating, I was working 16 hours a day. I was almost method acting without intending to. I do wonder now how people can do this kind of role when they have a family,” she told the Daily Mail. “It was more difficult than anything I’ve ever experienced before. I like to go home and be myself but with this one I didn’t get the chance. It didn’t leave me.”

Portman’s portrayal of the competitive ballerina was pretty convincing. She took home the Golden Globe and the Academy Award for Best Actress for her performance.

5. Christian Bale

For his role in the psychological thriller The Machinist, Christian Bale really committed himself to his character, Trevor Reznik. He lost 63 pounds for the part by living off of coffee and apples. When filming ended, he only weighed 121 pounds.

According to Bale, he hadn’t worked for a while prior to landing this role. “I just hadn’t found scripts that I’d really been interested in. So I was really dying for something to arrive. Then when this one did, I just didn’t want to put it down. I finished it and, upon the kind of revelation that you get at the end, I immediately wanted to go back and re-visit it, to take a look at what clues I could have gotten throughout,” he told BBC. “There are an awful lot, but they’re really nicely done because they’re very, very subtle. Sometimes you get a really great character and the movie ain’t so great; this one seemed to me to be a really great character and a potentially great movie as well.”

4. Hilary Swank

Hilary Swank took her role as a transgendered man in Boys Don’t Cry very seriously. The relatively unknown actress prepared for the role by dressing and living as a man for a month. This included wrapping her breasts in tension bandages and putting socks down the front of her pants. She also reduced her body fat to seven percent to accentuate her facial structure and refused to be seen by the cast or crew out of costume. Her neighbors reportedly didn’t recognize her when she would be coming in and out of her apartment – they thought she was a male relative.

“I walked around trying to pass as a boy for five weeks before filming that movie,” she said. “Seeing what worked and what didn’t work, and losing a bunch of body fat so that my face would be thinner. My neighbors thought that I was my cousin Billy from Iowa.”

3. Forest Whitaker

Forest Whitaker went method when he portrayed the Ugandan dictator Idi Amin in The Last King of Scotland. He gained 50 pounds, learned Swahili, and mastered Amin’s East African Dialect. He also read books about him, watched news clips and documentaries that featured him, and spent time in Uganda meeting with his friends, relatives, generals, and victims.

“I went there with the purpose of understanding what it was like to be Ugandan…I sat with Idi Amin’s brother underneath a big mango tree and he told me stories about what Idi was like and how he used to come to town and pull together soccer or rugby games. It all helped me with figuring out the way he behaved and the way he thought, so that 24 hours a day, even in my dreams, I was totally consumed by the character of Idi Amin,” Whitaker told The Guardian. “It wasn’t until the movie was over that I decided I could let go of the character, so the first thing I did was take a shower because I figured I could wash him off by scrubbing myself. I was in a room by myself, so I started yelling to get his voice out of me and get my own voice back.”

2. Jared Leto

To accurately portray a drug addicted transgender woman in Dallas Buyers Club, Jared Leto went method. He lost 30 pounds, shaved his eyebrows, waxed his entire body, and stayed in drag on- and off-set. He made sure to be in character 24-hours a day and even met with people in the transgender community to get feedback on how to make his performance more real.

Matthew McConaughey, his co-star from the film, had nothing but praise for Leto. “Some people may have been put off with Jared’s ideal of being in-character the entire time. Well, too bad, it was good for him and it was good for me; it would have been easy for an actor to caricaturize in this role, but Jared kept Rayon grounded in her eccentricities. Jared went for ‘human,’ and that made him so much easier to act with, and more truthful,” he said. Leto’s performance ended up winning him the Oscar, Golden Globe, and Screen Actors Guild Award for Best Supporting Actor.

1. Eddie Redmayne

Eddie Redmayne delved deep into Stephen Hawking’s life to portray him in The Theory of Everything. He spent six months researching and watching interview footage of the famed physicist. He also worked with a movement coach to capture Hawking’s physicality. In addition, Redmayne consulted medical textbooks and talked to nurses who worked with Hawking over the years to understand how his condition has evolved. “I prepped four months. It was intense. I visited London’s clinic, where they treated him. I met others afflicted. I familiarized myself to work out specifics. This was a privilege, but it was highly intimidating. I was very nervous. With a coach I worked training certain muscles never before used,” he told Page Six.

All the hard work is definitely paying off. Redmayne has won the Golden Globe Award, the Screen Actors Guild Award, the Oscar and the BAFTA Award for Best Actor for his performance.