The Atomic Blonde and actor’s actor, the indefatigable Charlize Theron, is delivering another gut-wrenching, groundbreaking, career-defining performance in the 2018 Sundance hit Tully.

Theron plays a mother of three suffering through postpartum depression with raw emotion, physical intensity, and a keen sense of verisimilitude–not to mention, with an extra 50 pounds around the midsection.

“I did this, yes, but mothers do this every single day, and they get pregnant and they gain all that weight, and it takes them a year and a half to lose it. And if they don’t, they get judged. And I feel like I had to do it for the film,” Charlize told Ellen DeGeneres. “If I was going to play a mother who’s having her third child, I felt a responsibility to that. And I think for myself, as an actor, I wanted to feel as much as I possibly could.”

When Theron committed to the role, she was extraordinarily fit as a result of her power-packed performance in Atomic Blonde for which she worked out like a UFC fighter to play the brutal and, in fact, lethal spy Lorraine Broughton. She trained in a number of disciplines including martial arts, boxing, kickboxing, wrestling, judo, as well as strength and conditioning training. After the shoot, Theron was looking forward to beach time in a bikini.

But her Tully work demanded she get to work and start consuming large quantities of food; her favorite was overindulging on potato chips. “I had a bag in my car, a bag in the bathroom, a bag in the kitchen, a bag on the couch, a bag in my trailer–everywhere I went, there was just a bag,” she said.

Charlize drank sugary sodas and visited In-n-Out Burger three times a week for the greasy burgers and decadent milkshakes. The normally svelte actress would wake up in the middle of the night to eat macaroni and cheese to keep the pounds on. And although she says the first three weeks of the binge were close to heaven, the overabundance of processed foods and high-sugar content not only left her lethargic and chronically tired, it actually triggered depression in the star for the first time in her life. “I really struggled with it. It was hard,” she said.

Charlize did gain a significant amount of weight at the age of 27 playing the deranged serial killer Aileen Wuornos in Monster. Her performance won her critical acclaim and many awards including a Best Actress Oscar. Back then, getting back into shape proved to be a simple task. “I just didn’t snack for a week,” she recalls. However, when it came to recovering from her Tully role, losing the pounds proved to be much more of a challenge. “Six months into it, I called my doctor and said, ‘I’m dying.’ And he said, ‘No, you’re just 42.’” It took her a year and a half to shed the weight.

Although Charlize doesn’t think gaining weight for a role is heroic, it is also not inconsequential. Indeed, gaining or losing a significant amount of weight and risking your overall health has long been a factor in delineating legendary status in the subculture of Method acting. Think of DeNiro in Raging Bull, Christian Bale in The Machinist, or Matthew McConaughey in Dallas Buyers Club. It would have been easy for Charlize to wear a prosthetic bodysuit, but that just wouldn’t cut it for one of the most dedicated actresses in Hollywood today.  

But Charlize doesn’t consider herself a tortured artist; she, in fact, loves her job as an actress and she makes sure to separate work from her personal life. Theron gets enough sleep and enjoys her weekends at home with loved ones, making sure to “switch on” when she arrives back at work.

Tully is now playing in theaters across the country.