Charlize Theron Struggled With Depression After 22kg Weight Gain For New Film

The prep included mac and cheese at 2am - by Poppy Jakobs

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 - Official International Trailer 2 (Universal Pictures) HD

Tully is released in cinemas in Australia on May 10.