Here's How Jake Gyllenhaal Lost 30 Pounds For His New Movie 'Nightcrawler'

Jake Gyllenhaal's creepy new indie movie "Nightcrawler" just hit theaters on Friday and has already raked in over $11 million at the box office.

In the film, Gyllenhaal appears gaunt and as a much slimmer version of his usually more buff self.

For the majority of this year, Gyllenhaal was sporting a much leaner look while he shot "Nightcrawler."

"Nightcrawler," in which Gyllenhaal both stars and is a producer, is the story of a career-hungry young man who stumbles upon the underground world of L.A. freelance crime photojournalism.

Gyllenhaal spent three months in pre-production brainstorming with screenwriter and first-time director Dan Gilroy on the appearance of his character, Lou.

"I knew that [Lou] was literally and figuratively hungry," Gyllenhaal told Us Weekly, adding that he got into character by transitioning into a "mode where I was always a bit hungry."

In order to drop 30 pounds from his 180-pound frame, Gyllenhaal told Variety: "I would try to eat as few calories as possible. I knew if I was hungry that I was in the right spot. Physically, it showed itself, but chemically and mentally, I think it was even a more fascinating journey. It became a struggle for me."

"He'd have a bowl of luxury chewing (gum) and they were, like, really elaborately flavored, to trick his brain into thinking he was having a meal," Gyllenhaal's co-star Riz Ahmed told The Canadian Press at the Toronto Film Festival this week. "So he was on his exercise bike having chewing gum and, like, almond tea with one calorie."

He also said Gyllenhaal was aware and apologetic about his sometimes-sour demeanor, "So he was like: 'Sorry I'm grumpy, I haven't eaten."'

On some nights during shooting, Gyllenhaal told Variety he wouldn't eat at all, or he'd only take small bites of meat, crackers, or kale salad. To stay lean and fit, he would run 15 miles from his house to the film's set.

"There was a general sense that he was a coyote," Gyllenhaal says. "I just wanted to live that way."

Gilroy adds: "When you watch the film and see the angularity of his face, the hollow cheeks, the way that his eyes become prominent - it's such a haunting look for a night shoot.""Nightcrawler"

Gyllenhaal's co-star and Gilroy's wife, Rene Russo, told E! Online, "It's incredible what he put his body through. I actually was worried."

But this isn't Gyllenhaal's first physical transformation for a film.

In 2010, the Oscar nominee added major muscle to his physique for "Prince of Persia." The actor told UsWeekly at the time that he would eat six small meals loaded with protein, carbs, and fats.

Disney/"Prince of Persia"Gyllenhaal, however, says there was no special diet to shed pounds for "Nightcrawler."

"I just love this movie," he said. "That's how I did it. There really was no technique."

Watch the "Nightcrawler" trailer below. Gyllenhaal's performance is already being called "stunning":