A good movie needs a good actor for it to work. As such, a good actor will do almost anything to portray the character as realistic as possible. For instance, if the role is a Kung Fu specialist, the actor usually learns the art of combat prior to starting the film, just like what Keanu Reeves did for the movie “The Matrix.”

What about the physical aspect of the role? Actors wear makeup all the time in addition to prosthetics to become the character they are trying to portray. However, there are times that actors need to make drastic changes to their bodies to make the role more believable.

With that in mind, here are the actors who made drastic weight changes to their bodies just for a specific role.

Chris Pratt in ‘Guardians of the Galaxy’

Before Chris Pratt joined the cast of the superhero film “Guardians of the Galaxy,” he was best known for his role in the award-winning TV series “Parks and Recreation.” Pratt played the role of Andy Dwyer, a not-so-bright but lovable and chubby character. Pratt didn’t exactly win any “Sexiest Man of the Year” awards during his time in the hit comedy series.

According to MensFitness, he underwent drastic changes to his appearance after being cast in “Guardians of the Galaxy” where he played the character of Peter Quill, also known as Star-Lord.

Pratt needed to bulk up in order to play the superhero.

In a span of six months, Pratt stuck to a strict diet in addition to an intense training program and as a result, the actor managed to lose 60 pounds.

Natalie Portman in ‘Black Swan’

Natalie Portman already has a small frame, so it’s amazing to know that she intentionally dropped 20 pounds just to play the role of a ballerina in the film “Black Swan.” In fact, Portman went on a diet much like a real ballerina would do, E!

Online reported.

To prepare for the role, Portman trained as a ballerina for up to 16 hours per day. She lost so much weight that she thought she might die, according to a report by Entertainment Weekly. However, all the hard work and training paid off as Portman won the Academy Award for Best Actress for her portrayal as Nina Sayers in the film.

Christian Bale in ‘The Machinist’

Christian Bale is known for making small transformations to his body for specific roles. His most shocking transformation is probably the time where he dropped 65 pounds to play the role of Trevor Reznik in psychological thriller film “The Machinist.”

MoviePilot noted that during his diet, Bale only ate an apple and a can of tuna per day and he controlled his appetite by smoking cigarettes. Bale planned to continue his diet until his doctors advised him otherwise. After the “The Machinist” finished filming, Bale only had four months to bulk up to play the role of Batman.