Having shaved her head for her role in Mad Max: Fury Road, gained 30 pounds, and worn prosthetic teeth to pull off the role of real-life serial killer Aileen Wuornos in the 2002 film Monster, it's safe to say Oscar-winning actress Charlize Theron isn't exactly afraid of altering her physique in order to convince an audience.

However, it appears the 41-year-old's latest metamophosis for the American comedy-drama Tully proved to be one of her most challenging to date.

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In a recent interview with Variety magazine, the South African activist opened up about how difficult it was to pack on 35 pounds for her role as a mother-of-three in the Jason Reitman film, compared to her preparation for her character in Monster 13 years ago.

'It was brutal in every sense,' she explained. 'This time around, I really felt it in my health.

'The sugar put me in a massive depression. I was sick. I couldn't lose the weight. I called my doctor and I said, "I think I'm dying!" And he's like, "No, you're 41. Calm down",' she added.

However, piling on the pounds for the motherhood-focussed film isn't the only challenge that's recently put the star's health at risk, in the name of art.

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The J'adore Dior model also admitted that during the making of her up-coming spy thriller, Atomic Blonde, she twisted her knee, bruised her ribs and had to undergo extensive dental surgery as a result of clenching her teeth when having to flip men over her shoulders.

Describing the physical toll she endured to play undercover agent Lorraine Broughton, Theron said: 'It happened the first month of training. I had severe tooth pain, which I never had in my entire life.'

'It was tough. You want to be in your best fighting shape, and it's hard. I had the removal and I had to put a donor bone in there to heal until I came back, and then I had another surgery to put a metal screw in there,' she explained.

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During the interview, the mother-of-two also opened about her pride for Monster director Patty Jenkins' work on Wonder Woman, amid what she describes as the 'f*cking caveman-like' treatment of women in Hollywood.

'We've had moments like this, where women really showcase themselves and kind of break glass ceilings. And then we don't sustain it. Or there's one movie that doesn't do well, and all of a sudden, no one wants to make a female-driven film.

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'I am ashamed that I'm part of an industry that has never allowed a woman to work with a budget higher than what the budget has been on Wonder Woman.

'That's so f*cking caveman-like. I am always hoping that this is the movie that's going to change it and keep it for us,' she added.

Hear hear, Charlize.