Actor Jake Gyllenhaal's acting in the flick "Nightcrawler" has been receiving high praises from viewers and critics alike. However, because he had to lose 30 pounds for his role as a deranged underground crime-scene videographer, his mom was certainly worried about his sudden frailty.

After a reporter asked him at the premiere of his movie at the Toronto International Film Festival if his mother worried about his dramatic weight loss, the actor replied, "You're the first person to ask that question and I'd say my mother was worried. I would say she just wanted me to be careful. But she also knew and knows how seriously I take what I do and she respects that."

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He went on to explain that his mom knew that he could handle the physical pressure to lose weight for the role and, that he would always stay within a safe weight. However, like any mother, she worried and would usually comment that he was getting cranky and that he should eat something.

The actor's co-stars Rene Russo and Riz Ahmed were also at the premiere and at the pre-party for the movie at Soho house. Russo's husband Dan Gilroy wrote and directed the flick.

Russo shared that like Gyllenhaal's mother, she was worried about the physical toll his weight gain took on him, but she also shared that she was extremely in awe of his dedication to the role despite the difficulties his body had to undergo.

Ahmed, on the other hand, explained what Gyllenhaal had to live on during the shoot in order to lose the weight.

"He'd have a bowl of luxury chewing (gum) and they were, like, really elaborately flavoured, to trick his brain into thinking he was having a meal. So he was on his exercise bike having chewing gum and, like, almond tea with one calorie," Ahmed shared.

"Nightcrawler" will open in theaters on Oct. 31.