Brendan Fraser says that his transformation for The Whale was so drastic that he began experiencing vertigo from the prosthetics.

"I had to learn how to move in a new way," Fraser told journalists at a press conference ahead of the film's premiere at the Venice Film Festival.

The Whale stars Fraser as Charlie, a reclusive English teacher who tips the scale at over 600 pounds after eating to cope with loss. Over the course of a week, Charlie attempts to reconnect with his daughter Ellie (Stranger Things' Sadie Sink) one last time as he faces congestive heart failure. The stunning transformation was created with a prosthetic suit worn by Fraser aided by CGI, rendering the actor almost unrecognizable as Charlie moves about his apartment with the help of a walker or wheelchair. But the George of the Jungle actor said that the prosthetics had their downside as well.

"I developed muscles I did not know I had. I even felt a sense of vertigo at the end of the day when all the appliances were removed," Fraser said of the shift in weight. "It was like stepping off the dock onto a boat in Venice. That [sense of] undulating."

Fraser says The Whale Character is "Most Heroic Man" He's Ever Played

Brendan Fraser as Charlie
A24

Fraser also told Variety that his role in the upcoming Darren Aronofsky film gave him an appreciation for those who have bodies like Charlie's.

"It gave me appreciation for those whose bodies are similar," he said. "You need to be an incredibly strong person, mentally and physically, to inhabit that physical being."

Related: Brendan Fraser Brought to Tears By 6-Minute Standing Ovation for The Whale

He went on to express that the role of Charlie was a considerable challenge, but Fraser saw his character as a hero.

"By far and away, I think Charlie is the most heroic man I've ever played because his superpower is to see good in others and bring them out in them."

The author of the play The Whale is based on, Samuel D. Hunter, says Charlie's story comes from a "pretty personal place."

"I have a history of self-medicating with food a history [of] depression. I used to be a lot bigger than I am now," Hunter said, speaking at the press conference. "I also went to a fundamentalist religious high school. I was a gay kid in a fundamentalist religious high school, which was not easy...This might be my most personal [play]."

A24's The Whale arrives in theaters December 9.