HOLLYWOOD, Feb 24, 2008 (AFP) - Tilda Swinton literally munched her way to an Oscar after piling on the pounds to play the role of a scheming corporate lawyer in the thriller "Michael Clayton."

The 47-year-old British actress, who scooped the Academy Award for the best supporting actress here Sunday, won critical acclaim as legal counsel Karen Crowder, who finds herself in too deep and attempting to cover up a scandal.

To prepare for the part, Swinton put on weight after deciding that her character should feel "uncomfortable in her own skin."

"I think it was really important that she should feel really uncomfortable in her skin, because she's a poor actress badly cast.

"I wanted her to have this sort of itchy feeling about her body so her clothes were always either too tight or her underwear was too tight but her clothes actually don't fit."

Swinton's weight-gain is apparent early in the film where her character is pounding away on a treadmill, with a pot belly clearly visible.

"It means that success is within their grasp, someone with a pot belly running on a treadmill, it moves me. It means this person is constantly striving for something that they can't quite get their hands on."

Born in London in 1960, Swinton made a name for herself by eschewing the conventional and embracing risky, unusual roles, playing everything from an evil ice queen in "The Chronicles of Narnia: The Lion, the Witch and the Wardrobe" to an androgynous archangel Gabriel in "Constantine."

A Cambridge graduate, Swinton's early movie career was marked by appearances in European arthouse movies, where she appeared in several movies directed by the late British filmmaker Derek Jarman.

She rose to international prominence in 1992 when she starred in Sally Potter's Oscar-nominated "Orlando."

Following a gritty performance in "The War Zone," Tim Roth's harrowing drama about incest in 1999, Swinton appeared in several mainstream films.

She starred opposite Leonardo DiCaprio in 2000's "The Beach," the adaptation of Alex Garland's hit novel about backpackers in Thailand.

The following year she starred with Tom Cruise in "Vanilla Sky" before popping up in a memorable cameo in 2002 as a Hollywood movie executive in Spike Jonze's "Adaptation."

More recent films have included Jim Jarmusch's "Broken Flowers" with Bill Murray and the evil White Witch in the successful big-screen adaptation of C.S. Lewis's fantasy books "The Chronicles of Narnia."

Swinton lives in the north of Scotland with her husband and their twin children, Xavier and Honor.