Cillian Murphy's physical transformation in the upcoming summer epic Oppenheimer is making headlines — but by Hollywood's standards, his weight loss plan was pretty tame.
Murphy, 47, was eating just one almond a day to shed the pounds to play gaunt scientist J Robert Oppenheimer, who famously survived on a diet of martinis and cigarettes.
Nicotine was a factor in Christian Bale's extreme transformation for The Machinist, where he lost 62lbs — or about a third of his bodyweight — by surviving on a diet of an apple and black coffee a day and taking up smoking.
Charlize Theron went to the opposite extreme, however, after she gained 30lbs for her Oscar-winning role in Monster where she played a serial killer. She went even more extreme for a 2018 drama that saw her gain 50lbs by gorging on burgers, milkshakes and potato chips.
Below, DailyMail.com highlights five dramatic transformations celebrities have undergone for movies:
Christian Bale (pictured left in a 2002 film) is famous for his body transformations. One of the most severe was when he lost 62lbs in order to play insomniac Trevor Reznik (pictured right)
One of the most dramatic body transformations in Hollywood history is that of Christian Bale. The actor lost 62lbs, or a third of his weight, for a psychological thriller.
When he was cast as machinist Trevor Reznik for the 2004 movie 'The Machinist' who was emaciated due to his insomnia, the star set himself a target of slashing his weight from 182lbs to just 120lbs.
The move worked, with reviewers commenting on the dramatic transformation at the time — and the performance earned him a nomination for Best Actor.
Mr Bale revealed he lost the weight in just four months after switching his normal diet for one apple, a tin of tuna and a black coffee every day. He also smoked cigarettes to help reduce his appetite.
This was a measly diet of less than 200 calories per day, well below the 2,500-calorie average recommended for men.
To help keep him on track, Bale said he would regularly sit around wearing headphones but not actually listen to anything so he could hear what was going on around him without being distracted.
He added to GQ: 'Also, at the time I was engaged in a very filthy habit of smoking. So, I was rolling my own cigarettes and sitting there puffing away.'
Mr Bale has also previously swung the other way, bulking up to 220lbs for his role of Batman in The Dark Knight.
Years later, he gained weight again for his role in the 2018 film Vice. Mr Bale gained 40lbs to play the 46th US Vice President Dick Cheney.
But talking about his dramatic weight fluctuations in 2019, at the age of 45, he said he couldn't keep transforming his body the way he had previously.
'I just can't keep doing it. I really can't,' he told GQ. 'My mortality is staring me in the face.