Jake Gyllenhaal's fasting for 'Nightcrawler'

Actor Jake Gyllenhaal drove himself "insane with hunger" while filming for "Nightcrawler".

The actor's co-star Riz Ahmed, who plays Gyllenhaal's sidekick Rick Carey in the film thought he was going to be eaten alive during the movie, because Gyllenhaal was so hungry and living off a diet of chewing gum to lose 30 pounds for the role, reports femalefirst.co.uk.

"Jake lost a lot of weight for the role, he was literally surviving off chewing gum and driving himself with hunger, which makes sense because his character is desperately hungry for success," Ahmed told Metro newspaper.

"He's looking at me in the film like he might want to eat me. There was this primal energy coming off him," he added.

Despite the concerns, the star found working with Gyllenhaal "really inspiring".

"He's someone who really pushes himself to limits," he said.