Charlize Theron has retired from taking on roles with extreme body transformations.

“I will never, ever do a movie again and say, ‘Yeah, I’ll gain 40 pounds.’ I will never do it again because you can’t take it off,” the “Fast X” star told Allure. “When I was 27, I did ‘Monster.’ I lost 30 pounds, like, overnight. I missed three meals and I was back to my normal weight.”

Theron won the Academy Award for best actress for “Monster,” in which she starred opposite Christina Ricci. She has previously spoken out about easily snapping back to her previous weight after the 2003 biographical crime drama. But Theron said that with age, shedding excess weight gained for roles became nearly impossible. She learned that first-hand after putting on 50 pounds for her 2018 dramedy “Tully.”

“Then I did it at 43 for ‘Tully,’ and I remember a year into trying to lose the weight, I called my doctor and I said, ‘I think I’m dying because I cannot lose this weight.’ And he was like, ‘You’re over 40. Calm down. Your metabolism is not what it was.’ Nobody wants to hear that,” Theron said.

Theron played an exhausted mother of three in “Tully,” which she produced alongside director Jason Reitman. Back in 2018, she opened up about facing “depression” while transforming into the character.

“I gained close to 50 pounds for this film,” Theron told ET at the time. “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. 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.”

She added, “The first three weeks are always fun because you’re just like a kid in a candy store. So it was fun to go and have breakfast at In-N-Out and have two milkshakes. And then after three weeks, it’s not fun anymore. Like, all of a sudden you’re just done eating that amount and then it becomes a job. I remember having to set my alarm in the middle of the night in order to just maintain [the weight]. 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.”

It took Theron a year and a half to lose the extra pounds she gained for “Tully,” an experience she called a “very long journey.”

“It’s hard because I had press junkets and movies around it and nobody knew that I had done it for this,” Theron said at the time. “When the first photos came out, everyone [thought it] was prosthetics. And then I went on press junkets and it was like nobody knew.”

Elsewhere in her Allure interview, Theron said, “I’ve always found it so funny when I’ve gained weight for movies and then had to go onto a red carpet. I call [my stylist, Leslie Fremar] and say, ‘I’m doing this movie about postpartum depression and I’ve gained like 40 pounds.’ And she’s like, ‘Oh, my gosh! Oh, my gosh! How am I gonna dress you?’ It’s not something that you can just figure out last minute… She’s put a lot of blazers over open backs for me.”

It’s not just losing weight that became harder for Theron as she got older. Now 48, she said it “bums her out” that when she hurts herself on the set of an action movie, “I take way longer to heal than I did in my 20s.”

“More than my face, I wish I had my 25-year-old body that I can just throw against the wall and not even hurt tomorrow,” said Theron, who in the past decade has starred in action movies including “Mad Max: Fury Road” and “Atomic Blonde. “Now, if I don’t work out for three days and I go back to the gym, I can’t walk. I can’t sit down on the toilet.”