Charlize Theron has revealed she struggled with depression after gaining more than 20kg for a film role.
Theron put on 22kg in just three months for her performance in the upcoming film Tully, about a New York mother pregnant with her third child's relationship with her new nanny.
Speaking to Entertainment Tonight, the actress revealed the transformation took a toll on her mental health.
"I just I wanted to feel what this woman felt, and I think that was a way for me to get closer to her and get into that mindset," Theron said. "You know, it was a huge surprise to me.
"I got hit in the face pretty hard with depression. Yeah, for the first time in my life I was eating so much processed foods and I drank way too much sugar.
"I was not that fun to be around on this film."
While the first three weeks for Theron were “fun” with regular trips to In-N-Out for breakfast (including two milkshakes), the 12 weeks after were tough.
"All of a sudden you're just done eating that amount and then it becomes a job," she told the publication. "I remember having to set my alarm in the middle of the night in order to just maintain [the weight]."
Theron added: "I would literally wake up at two in the morning and I'd have a cup of cold macaroni and cheese just next to me.
“I would wake up and I would just eat it...I would just, like, shove it in my throat. It's hard to maintain that weight."
Losing the weight was "hell", too. "It took about a year and a half," the Atomic Blonde star said. "It was a long journey, very long journey."
Tully marks the third time Juno and Young Adult director Jason Reitman has collaborated with writer Diablo Cody.
Tully is released in cinemas in Australia on May 10.