Weight watchers: shape-shifting for the screen

Michael Fassbender is the latest star to manipulate his weight for a role - a process that can have serious side-effects if actors don't follow medical advice

SOME actors, such as Eddie Murphy in The Nutty Professor and Norbit, wear fat-suits to alter their appearance. Some go the distance, gaining or losing dramatic amounts of weight to add authenticity.

"It's not as easy as it looks," says Madelyn Fernstrom, director of the Weight Management Centre at the University of Pittsburgh Medical Centre. "I counsel patients all the time that these people have medical monitoring, special diets and exercise regimes."

Dr David Katz, an expert in nutrition and public health at Yale University Medical Centre, says actors can lose and gain weight responsibly by taking a medical screening first. He warns that older actors could encounter health problems on such diets and that child actors should never be allowed to attempt them.

"It's all part of the work," Daniel Day-Lewis told me in a 2006 interview. "You do it if you have to, if it helps to tell the story, and if you can't, you don't. They are really obsessed with it in America, and how many pounds you gained or lost. I wouldn't want to be an actress. That's for sure."

Raging Bull:As Jake LaMotta, Robert De Niro piles on the weight to the point where he is unrecognisably fat and jowly - and wins his second Oscar.

Full Metal Jacket:Cast as an obese soldier, Vincent D'Onofrio puts on 32kg.

The Machinist:Christian Bale's skeletal physique is revealed in several shirtless scenes.

Cast Away:Stranded on a desert island with not a grocery store in sight, Tom Hanks sheds 25kg, and gets an Oscar nomination.

Rescue Dawn:Having bulked up for Batman Begins, Bale drops weight again for this prisoner-of-war camp drama in which Jeremy Davies is even thinner.

The Ballad of Jack and Rose:Daniel Day-Lewis plays an ailing hippie. The film's director, his wife Rebecca Miller, said: "You can really see his organs, and even the outline of his kidneys. Terrifying."

Bridget Jones's Diary:Renée Zellweger puts on weight, loses it for Chicago, and puts it on again for the Jones sequel.

Monster:Munching on doughnuts and crisps, Charlize Theron gains 14kg and an Oscar as serial killer Aileen Wournos.

Dreamgirls:Beyoncé Knowles loses 9kg to play a soul singer modelled on Diana Ross. "I was inspired by Tom Hanks," she said.

Syriana:George Clooney adds facial hair and 16kg - and collects an Oscar.

Chapter 27:Jared Leto gains 28kg to play John Lennon's assassin, Mark Chapman - and gets gout when he drops the weight.

Triage:Articles abound, feigning concern at how skinny Colin Farrell looks as a war photojournalist in his latest movie.