Jennifer Aniston has said as soon as she read the script for her new film Cake she felt the role was hers.

The former Friends star shows a very different side of herself in the indie flick exploring the theme of grief, in which she wore no make-up to play a woman suffering from chronic pain.

Jennifer revealed on the red carpet at the Toronto International Film Festival, where she was joined by fiance Justin Theroux, that when she read the script: "I felt myself already shooting it when I was reading it, instantly, it was mine."

She added: "It's poetic, it's absolutely beautifully written from top to bottom - a beautiful arc, exquisite characters."

The film sees Jennifer's character Claire Simmons befriend the husband of a woman in her chronic pain group who has committed suicide, and looks at the effects of death on the living.

Jennifer said: "It was an incredible experience to really channel your empathy, which we all have for people who we know have lost a loved one or been through any severe trauma or tragedy. And how people get through it, how they survive it, I find it remarkable that people overcome what they have to overcome."

Avatar star Sam Worthington plays the widowed husband in the movie. He revealed how it had been important to balance the dark themes of the film with humour and lightness.

He said: "The movie is about a woman that's dealing with grief. That's a very, very heavy theme and so our job is to make that kind of buoyant and bring a bit of levity into that.

"My character supports Jen's character through that in the movie and that's what I wanted to do the movie for, I wanted to support Jennifer Aniston's transformation."

He added: "Everyone's at their own level of how they deal with grief. My character's actually dealt with it, I don't think he's dealt with it in the best possible way, but I like that exploration.

"We're all connected by two things - death and taxes. So it's a universal theme, once we explore it people can associate with it. That's the thing - you don't want to be glib with it and you don't want to be too heavy-handed."