Brendan Fraser's autistic son helped shape his performance in 'The Whale'.

The 53-year-old actor - who has Griffin, 20, Holand, 18, and Leland, 16, with his ex-wife Afton Smith - plays Charlie, an obese recluse, in Darren Aronofsky's new movie and he explained he "understands intimately" what it's like for larger people, while admitting his own love for his family drove his understanding of his character, who sets out to reconcile with his estranged daughter.

Speaking to Freddie Prinze Jr. for Interview magazine, he said: "I have three kids of my own. My oldest son Griffin has special needs. He’s autistic. He just turned 20. He’s a big kid. He’s six foot five. He’s got big hands and feet, a big body. I understand intimately what it is to be close to a person who lives with obesity.

"And because of the beauty of his spectrum - call it a disorder if you will, I disagree with you - he knows nothing of irony. He doesn’t know what cynicism is. You can’t insult him. He can’t insult you.

"He’s the happiest person and is, in my life and many others’, also the manifestation of love.

"Being with my kids and their mom and our family has given me such love that if ever I needed to hold something of value up to try and translate that to what was important to Charlie, I didn’t have to look far."

Long after filming has finished on the movie, Brendan still can't stop thinking about his character.

He said: "I think about this guy all the time. I interviewed people on Zoom calls in researching for this, connections made possible by Dr. Goldman at the Obesity Action Coalition. It’s a support and resource group that has a huge following and membership online.

"It’s essentially a place where families and people who live with people who are obese, or are obese, can go to when they need health services, referrals, everything. It’s a wonderful organisation.

"The people I talked to gave me something so honest that I really questioned if I was qualified to have this information. Something I learned, as heartbreaking as it is, is that each person who told me their story had one thing in common: There was someone in their youth who was very cruel to them by the way they spoke to them, and it set in motion the rest of their life. Sadly, it most often was a father, I noticed.

"So when I learned that, I was like, 'Well, I’ve got to try and do something to break that cycle.' And if this is what I can contribute, that’s good enough for me."