When Lily Collins read the screenplay for To The Bone - a Netflix original movie about a young woman dealing with anorexia but resisting all efforts to help her get better - she knew it was the work of someone who had experienced it firsthand.
This is because the British-American actress had battled eating disorders herself, something she detailed in her recently published memoir Unfiltered: No Shame, No Regrets, Just Me.
At a screening of the comedy- drama in Los Angeles this month, the star and the movie's writerdirector, Marti Noxon, spoke candidly about their own struggles with eating disorders, which are on the rise in many developed countries, including Singapore.
Collins, who appeared in the young-adult fantasy film The Mortal Instruments: City Of Bones (2013), says: "I, in the past year, have come out publicly speaking about my experience with eating disorders. I wrote a book last year and was writing the chapter on this and, a week later, I got this script.
"So to me, it was the world saying, 'Deal with this, talk about this, bring it to more people," says the 28-year-old, who is the daughter of British musician Phil Collins.
Noxon, 52, did not initially know this about Collins. But the two women formed an instant bond, and the actress says she knew from her character Ellen's "wit, sass and humour" that "the person who had written it had to have had experienced it because, on the surface level, most people's misconception is that it's a dark and dreary disease."
The story - which sees Ellen being treated by an unconventional doctor played by Keanu Reeves - is semi-autobiographical, explains Noxon, a prolific television scribe who has written for shows such as Buffy The Vampire Slayer (1997 to 2003), Mad Men (2007 to 2015), Girlfriends' Guide To Divorce (2014 to now) and Unreal (2015 to now).
"When I was around 14, I got anorexia and, for the next 10 years, I struggled with that and bulimia and then alcohol."
Noxon emphasises that the movie is just "about how one person got through it, but it's not prescriptive".
"And (Lily and I) have both been at pains to say this is one story, but there are, right now, 20 to 30 million people with eating disorders in America alone."
In Noxon's own struggle, the disorders were a way to escape from deeper psychological pain. "Underneath the control and the other things you get out of the beginning of this kind of disorder, the obsession and constant fixation on food and my body and all that stuff was all a way of numbing myself."
Laugh-out-loud moments such as Ellen's stepmother thinking a hamburger-shaped cake would encourage her to eat, and her biological mum bottle-feeding her, happened to Noxon for real.
"For many years, I would tell some of these stories and people would say, 'You've got to write about this'," says the first-time director, who is divorced from fellow TV writer Jeff Bynum and has two children aged 14 and 12.
She and Collins knew she had to tread carefully with this subject, however. They say the last thing they wanted to do is glamourise eating disorders, as some accused them of doing after the film's trailer was first released.
They do not want to add to the stigma, either. Noxon notes that many TV movies and documentaries on this topic "objectify the person who's ill as this kind of spectacle, an oddity or curiosity".
"But I started to feel like I could maybe help people understand that it's not a disease of vanity, that it really is a mental illness and maybe help more people have compassion for it," she says.
"And that the story could also be funny."
Collins made the controversial decision to lose weight for the role, which raised the question of whether there were "concerns with me doing a character like this that was so close to home after having gone through my own recovery period and was that smart?".
She decided it was worth the risk because she wanted to "pay tribute to the 16-year-old girl that I was when I started and tell a story that hopefully would make this conversation louder because it is taboo".
"And second, I was looking at this incredibly meaty part as an actor... It was my choice to lose weight, there was never a number given to me. It was about me re-entering the mindset that I knew so well when I had gone through it."
Collins says she took precautions to shed the weight safely and has since regained it.
"It was a 23-day shoot and I worked with a nutritionist the entire time and for eight months after. I had my mum, Marti, the producers, nutritionists - I was held accountable by everyone and anyone who knew me."
Researching the part also showed her she had way more to learn about eating disorders than she realised.
"We met with an anorexics anonymous group, we spoke to women in recovery, I watched documentaries, and I met with the head of a clinic that explained to me all the medical facts that, when I was suffering, I never sought out.
"This movie gave me that. It was incredibly therapeutic, but it also gave me the solid facts that I thought I never needed in my recovery. And thank god for this movie because it opened my eyes to a new form of recovery."
•To The Bone is available on Netflix.