In order to drop 20 pounds from his 180-pound frame, Gyllenhaal says: 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 mentally, I think it was even a more fascinating journey. I knew that [Lou] was literally and figuratively hungry, adding that he got into character by transitioning into a "mode where I was always a bit hungry." Gyllenhaal, however, says there was no special diet to shed pounds for Nightcrawler. On some nights during shooting, Gyllenhaal said 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.