Maisie Williams Details 25-Pound Weight Loss for New Role in Catherine Dior Biopic

While speaking to Harper's Bazaar UK, the Game of Thrones alum revealed that she lost around 25 pounds to portray World War II French Resistance fighter Catherine Dior in a bio-series about her life.

Titled The New Look, Williams said she was forced to shed weight -- and her long, brown tresses -- in order to become the iconic Catherine, rocking a shaved head and a slimmer figure for the part.

"I was eating very little, meditating all the time, burning candles and incense in my apartment," she told the magazine of her dramatic transformation.

She did, however, do it under the supervision of doctors, who she said regularly performed blood tests and monitored her heart rate.

Maisie also had to perspire pretty heavily to drop weight, adding that she'd be up at 4:00 a.m. some mornings to start sweating.

As for her diet, Williams said she was eating lots of dehydrated foods.

"The night before, at about 7:00 or 8:00 p.m., I was allowed to have something salty and dehydrating -- some smoked salmon and a tiny glass of wine," the 26-year-old continued. The number on the scale wasn't the only thing that changed for Williams -- so did her sleep pattern.

"Then I had a boiling hot bath with lots of salts in it. And I sort of levitated to bed and slept for maybe three hours, and woke up and had a handful of nuts," said Williams, who rose to fame playing Arya Stark on GOT. "I wouldn't be able to sleep through the night at this point. I kept waking up and feeling like a marble inside a bottle, rattling around."

As for how it differed from her role as the sword-wielding heroine, Williams said she was forced to focus on different muscles this time around.

"[This role] took over what I'm eating and how I'm moving and sleeping and thinking," she said of Catherine, who was also the sister of late designer, Christian Dior.

She even had some pretty vivid dreams while working on the series, including a "restricted, almost like sleep paralysis," as well as dreams of  "being trapped and attacked" and "horrible visions of men in uniform."

Despite the overwhelming experience, Williams said it was a pleasure to take on the part.

"Every day of filming was a reminder that we were portraying a story of the horrors that humans are capable of inflicting on one another, but also the magic and the hope and the love," she shared. "Ultimately, we wanted to make a show that was uplifting."

The New Look premieres February 14 on Apple TV+.