Christian Bale stunned audiences when the normally athletic actor appeared a gaunt 60 pounds lighter in the psychological thriller, 'The Machinist,' but a co-star says the radical transformation wasn't originally in the script.

In a recent interview, co-star Michael Ironside, said the weight loss was the result of a simple typo.

'The writer is only about five-foot-six, and he put his own weights in,' Ironside said. 'And then Chris did the film and Chris said, ‘No, don’t change the weights. I want to see if I make them.’ ... So those weights he writes on the bathroom wall in the film are his actual weights in the film.'

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Before and after: Christian Bale lost more than 60 pounds for his role in 'The Machinist' all due to a typo, said co-star Michael Ironshide

Yo-Yo dieter: After his weight plummeted to a shocking 121 pounds , the 6 foot actor swiftly bulked up again in just six weeks to play the Caped Crusader in Batman Begins by gorging on pizza and ice cream

In the interview with The Huffington Post, Ironside said the original role was meant for a much shorter actor.

But, he said, Bale was up for the challenge.

After his weight plummeted to a shocking 121 pounds , the 6 foot actor swiftly bulked up again in just six weeks to play the Caped Crusader in Batman Begins by gorging on pizza and ice cream.

Matthew McConaughey kickstarted a career rehab when he lost 21 pounds to play an AIDS patient in 'Dallas Buyer's Club'

He said: 'I overdid it because I was enjoying gorging. I was ignoring advice about taking it slowly because my stomach had shrunk, and I should just go with soups.

'I was straight into pizza and ice-cream and eating five meals in a sitting. My stomach expanded really quickly. I got very sick during that time but I enjoyed getting sick. I didn't mind it at all.

Starving artists: Actors who've risked drastic weight change for a role Christian Bale - Dropped 60 pounds to play the lead in 2004's 'The Machinist' Chris Pratt - The 'Parks and Rec' funnyman shed 60 pounds to play chiseled adventurer Peter Quill in the summer blockbuster 'Guardians of the Galaxy' Natalie Portman - Portman won an Oscar for her turn in 'The Black Swan,' a part that required her to lose 20 pounds and practice dancing five hours a day Robert DeNiro - The acting legend cemented his status by gaining a then-record 60 pounds for his Oscar-winning interpretation of troubled boxer Jack LaMotta in 1980's 'Raging Bull' Matthew McConaughey - In yet another Oscar-winning transformation, the Texas star dropped 21 pounds to play AIDS patient Ron Woodroof for 2013's 'Dallas Buyer's Club' Tom Hanks - To prepare for his part as a plane crash survivor alone on an island in 2001's 'Cast Away,' Hanks dropped 50 pounds Advertisement

'In that short amount of time I did actually go from 121 lbs right back up to 180 lbs which is way too fast so that resulted in some doctor visits to get things sorted out.'

Once again, the star dropped 30 lbs to play drug-addicted retired boxer Dicky Eklund in 2010's The Fighter, but he insisted embarking on extreme weight-loss and gain for roles has never been intentional.

He told MTV News: 'I have no goal of seeing if I can become invisible one day, eat so little that I disappear. I didn't take this job because I went, "Oh, there's a physical transformation needed." I always go, "Damn! There's a physical transformation needed!"

Severe yo-yo dieting is a regular practice in Hollywood, where extreme transformations can lead to critical acclaim.

Bale, Tom Hanks, Natalie Portman, and Matthew McConaughey are just a few to be awarded Oscars for drastic weight loss.

It's been almost a cliche way to garner acclaim ever since Robert Deniro gained a then-record 60 pounds to play over the hill boxer Jake LaMotta in Martin Scorsese's 1980 masterpiece, 'Raging Bull.'

Drastic weight changes often lead to critical acclaim, as it did for Natalie Portman when she shed 20 pounds for her Oscar-winning part in 'Black Swan'

But as Policy Mic notes, piling on or taking off the pounds for a movie can have long-term consequences.

The site argues that losing too much weight quickly can cause the actor to have problems digesting and even eating food at all.