While he's had quite the career in the theater, Jake Gyllenhaal's movie career is what's really captivated audiences. Sure, he's had a couple of clunkers. But, for the most part, he's contributed his deeply dedicated talents to a wide range of projects. This includes a role in the Marvel Cinematic Universe, a couple of cult classics, rom-coms, and critically acclaimed dramas. There's no doubt that Nightcrawler is among Jake's best works.

The 2014 film, which was written and directed by Dan Gilroy, followed an aspiring ambulance chaser (or 'stringer'/'paparazzi of pain') in the L.A. news industry. It was easily one of Jake's most intense and disturbing roles. Part of the reason for this was the decision to alter his own body for the performance.

Why Does Jake Gyllenhaal Look Different In Nightcrawler?

The main reason why Jake Gyllenhaal looked so different in 2014's Nightcrawler was the fact that he dropped a whopping 30 pounds for the role. Jake has a history of gaining and dropping pounds for parts, not unlike Christian Bale. In fact, directly after Nightcrawler, Jake packed on the muscle to play a boxer in Southpaw. Prior to Nightcrawler, he starred as two different characters in Enemy and as a physically imposing detective in Prisoners.

But for Jake's take on Louis 'Lou' Bloom in Nightcrawler, he needed to go in a very different direction. According to an article by The Guardian, Jake wanted to "look hungry" to portray the career-driven Lou. Both Jake and filmmaker Dan Gilroy have described Nightcrawler as really being about a man going into business for himself. But the business itself is portrayed as diseased and morally bankrupt. And the better Lou gets at it, the more of a sociopath he becomes.

What Did Jake Gylleenhall Do For Nightcrawler?

To look "hungry", Jake barely slept throughout the process of filming. The result made his eyes bulge out of his head and his face appeared gaunt. Paired with his weight loss, Jake's physical transformation caused audiences to second-guess if they were in fact watching the former Brokeback Mountain star.

While Jake claims he takes these transformations very seriously, he maintains that he also has fun with them.

Related: The Extreme Way Jake Gyllenhaal Prepared For His Role In 'Nightcrawler'

During an interview with Vulture, Jake described the internal contradiction when he takes on a performance such as the one in Nightcrawler.

"There’s a strange balance now with me where I take this extraordinarily seriously — almost pretentiously so — and then, at the same time, I think about how absurd it is, you know?" Jake said during his 2014 interview with Vulture. "That’s what allowed me to go and do Lou: I was in a dangerous space, and I did things to my body and my mind, but there was a lot of play to it. So, I mean, I like challenging myself. Sometimes when you’re acting onstage, your mind starts wandering. At a certain time in a run for a show, probably like 75 to 80 shows in, you’re giving a speech that for the first few nights meant everything to you, but now you’re running through your grocery list in your mind and figuring out what you’re going to buy at the bodega on the way home. I think that’s a good thing and an interesting thing, because you start to realize that the power of the words becomes unconscious and the story tells itself, but at the same time, I think you’re always trying to wake yourself up back into the moment. Because that’s where life is."

How Does Jake Gyllenhaal Feel About His Character In Nightcrawler?

There's no doubt that many find Lou to be a monster. But Jake doesn't exactly see it this way. As an actor, he can't and probably shouldn't. He has to approach each role from the inside out. And, of course, nobody really sees themselves as the villain of their story. What's more interesting to Jake is how the idea of what success is warps the person that Lou becomes in the film.

"It’s a society of 'succeed at any cost'," Jake said of the Western world's impact on young people and Lou, in an interview with The Guardian. "When do we decide that we’ve been successful in what we’ve done? Is there ever a point where that happens? Jobs are redefining themselves and you can find work in the strangest of places. If you have empathy, then I think you know how to navigate that in a way that’s not going to hurt people, but if you’re a character like Lou, it’s dangerous."

Related: This Is How Jake Gyllenhaal's Life And Net Worth Changed After 'Brokeback Mountain'

Jake went on to say that he doesn't see Lou as a sociopath, as most film critics and audiences have described him.

"The reason he doesn’t become unwatchable is because there’s this great innocence to him," Jake explained. "He’s almost from another time. You know when you hear those guys – Spencer Tracy, Danny Kaye, Jimmy Stewart?"

In his interview with Vulture, Jake further explained his take on the disturbing character.

"Well, one of the beautiful things about the character that Dan wrote was that nothing he says I would disagree with. He’s using this corporate kind of speak, self-help, Tony Robbins stuff — and I agree with all of it! I believe in ambition, and that’s an important quality for human beings to have. I believe in persistence and discipline and commitment and drive, which are all the things that Lou has. I think about that moment I look down at my phone and I’m scrolling and someone is talking to me, and I’m totally ignoring them, but unconsciously, I’m answering their questions, and that is where that is where that seedling of Lou can bloom in all of us. It’s that moment we all look down and say, 'Is it the State of the Union I’m going to click on, or am I going to click on the video of the cat that survived falling 40 stories?'"

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