Physical transformation on film

Nicole Kidman knew it when she donned a prosthetic nose to play Virginia Woolf in The Hours, Dustin Hoffman knew it when he put on a dress, wig and heavy make-up for Tootsie, and Kirk Lazarus, Robert Downey's "race-swapping" character in Tropic Thunder, certainly knew it. The fastest way to prove to the Academy that you can really act is to transform your looks as dramatically as possible, the so-called "oh, my God, that's ..." effect. The true professionals, however, go one step further, eschewing special effects in favour of physical transformation by other means. Matt Damon reportedly needed to take medication for two years after losing 40lbs to play a heroin-addicted soldier in 1996's Courage Under Fire. His current heavier look in forthcoming Steven Soderbergh whistleblower thriller The Informant! is arguably an even more dramatic transformation Photograph: PR

Jake Gyllenhaal came to most people's attention playing waif-ish Donnie Darko, but four years later he guzzled gallons of Weightgain 4000 to play beefcake soldier Anthony Swofford in Sam Mendes's Jarhead, about a US marine's experiences during the first Gulf war Photograph: The Ronald Grant Archive

Christian Bale seems to have little problem gaining or losing weight whenever the role requires it. The Machinist, Brad Anderson's paranoiac mystery in which Bale played an insomniac factory worker, was not your average popcorn flick. Bale reportedly lived on a diet of apples, coffee and cigarettes to get his weight down, then did it all over again two years later for Werner Herzog's Rescue Dawn, in which he portrayed hostage Dieter Dengler. Impressive, eh? Well, in between, he buffed up for Christopher Nolan's Batman Begins Photograph: PR

South African actor and former model Theron took home the best actress Oscar in 2004 after gaining 30 pounds to play serial killer Aileen Wuornos (she also wore prosthetic teeth and turned a blind eye to hair care). Roger Ebert of the Chicago Sun-Times wrote: "What Charlize Theron achieves in Patty Jenkins's Monster isn't a performance but an embodiment." Photograph: PR

In Sam Raimi's 2001 comic book caper Spider-man, Tobey Maguire was almost unrecognisable from the unfortunate hitch-hiker picked up by Johnny Depp and Benicio Del Toro in Fear and Loathing in Las Vegas. That was, of course, sort of the point, the toxic spider bite his character Peter Parker suffered having apparently given him super strength. The scene where Maguire checks himself out in the mirror reportedly drew audible gasps from early audiences, amid suggestions that the effect might been achieved through CGI Photograph: PR

George Clooney wasn't so gorgeous in 2005 political drama Syriana, but his understated performance as CIA agent Bob Barnes won him more major awards than all the Ocean's Eleven films put together, including the Academy Award for best supporting actor Photograph: Ronald Grant Archive

Michael Fassbender has produced standout performances in films as diverse as horror Eden Lake and Quentin Tarantino second world war romp Inglourious Basterds, but it was his role as IRA hunger striker Bobby Sands in Steve McQueen's Hunger that brought him to many people's attention. Fassbender's weight loss regime (14kg in 10 weeks) included long walks, a Jerry Hall yoga DVD and a very small tin of sardines every evening Photograph: PR

Renée Zellweger has signed on to play the curvy singleton in another instalment of Bridget Jones, but word is that this time she's refusing to pile on the pounds. If recent reports are to be believed, Zellweger is hoping Bridget's extra weight can be depicted via the use of - heaven forbid! - a fat suit. The new film centres on Jones's quest to have a baby Photograph: PR

He was hardly a skinny chap in the first place, but Tom Hardy certainly looked the part as Charles Bronson, supposedly Britain's most dangerous prisoner, in Dane director Nicolas Winding Refn's recent biopic. The bald pate, circus strongman lipwear and maniacal glare were complemented by at least three stone of extra muscle Photograph: PR

The ultimate master of the method, Robert De Niro took home his second Oscar in 1981 for his portrayal of boxer Jake LaMotta in Martin Scorsese's Raging Bull, all the way from the middleweight champion's glory days in the ring in the 1940s and 50s, to his destructive, corpulent later self. The actor reportedly put on five stone on a four-month binge eating sojourn to northern Italy and France, during which time the entire crew took a break on full salary Photograph: PR