Celebrity body transformations: Weight loss, gain and prosthetics to secure their roles

The ultra buffed, 55-year-old mum of four is gracing the cover of Perfect magazine, where she's flashing her super-toned biceps that are enough to make Arnold Schwarzenegger jealous.

She's wearing a micro mini and a halter top and has been crowned by the magazine as 'the Perfect icon'.

But Kidman is far from the only celeb who's putting their time and sweat in for a body transformation.

Fellow Australian Rebel Wilson has been rocking a new fit bod in recent times, and when back in the country recently she posted photos of her climbing the iconic Barrenjoey Headland on Sydney's northern beaches.

"It's never too late to improve yourself - to improve your health, your heart, your happiness, your harmony," she posted on Instagram.

Oscar winning actor Jared Leto has become well known for his commitment to roles, including wearing prosthetics, losing weight and gaining it back on.

He lost a reported 12 kilograms to play a heroin addict in Requiem for a Dream. For the movie Chapter 27 he gained 31kgs to play the role of Mark David Chapman, the man who assassinated John Lennon.

In the upcoming Morbius movie, Leto plays a super buff Michael Morbius, a man who becomes a vampire.

UK singer Adele shocked fans when she arrived at Notting Hill Carnival in London wearing a string bikini and skin-tight leggings.

American actor Jessica Chastain put weight on when she starred in movie The Help; and said her skin was left permanently damaged as a result of extensive makeup and prosthetics for her role in The Eyes of Tammy Faye.

Fellow US actor Sebastian Stan lost weight to play the role of rock star Tommy Lee for the series Pam & Tommy. In the past Stan buffed up to play Marvel character Winter Soldier.

Kim Kardashian has been turning heads for decades thanks to her body transformations and rumours of plastic surgery.

Some Natalie Portman fans were left shocked at how the 40-year-old mum of two had buffed up for her role in Marvel's latest flick Thor: Love and Thunder.

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Christian Bale has made changing his body a work of art, whether it was for Batman in The Dark Knight or losing weight in The Machinist.

Recently slimmed down TV and radio presenter Chrissie Swan has been taking to Instagram to show off her new fit bod.

"Walked 18kms yesterday and 12kms today for Fred's Big Run," she posted in reference to her fundraising for the Fred Hollows foundation.

And, far from hating pounding the pavement to get trim, Swan said walking helps "unknot all my life's tangles".

"Time alone, just walking, has given me the mindfulness and momentum to stay focused and constantly move forward to be the absolute best version of myself - yes for me - but also for everyone else I love who also deserves the best version of me," she posted on her page.