GMA: Renee Zellweger Transforms for New Role

April 23 -- It's the surprise hit movie of the spring: women and men all over the country who have peeked at Bridget Jones's Diary are applauding the young, single Londoner who tries to find a relationship without losing her mind.

American actress Renée Zellweger stars as Bridget Jones, an unmarried British woman in her 30s who obsessively counts calories, monitors her cigarette and alcohol intake, and — most of all — searches for the right man.

The movie shot to the top of the British box office in its first weekend, grossing $10 million, and marking the biggest ever opening for a British film. It came in at number three in the U.S. at $10.7 million on opening week, and jumped to the top spot this weekend.

Fitting the Role

To fit the role of the full-figured character, the svelte Zellweger had to gain about 20 pounds. But the actress considered the role a "gift" and said she didn't mind putting on weight for it.

"I felt great," actually said Zellweger on ABCNEWS' Good Morning America. "I felt more voluptuous than ever before in my life. I felt confident it was going to work any time we had to upgrade in various departments."

From Texan to Brit

Though she has been receiving great reviews, Zellweger, a 32-year-old native Texan, was considered an odd choice to play a London girl. Even she was surprised when picked for the role.

But once on the job, she put any comments from the press aside and let the role take over, the actress said.

Even before it hit the screen, Bridget Jones was a well-loved character, made popular by the international best-selling novel Bridget Jones's Diary, by Helen Fielding. And Zellweger said she was very conscious of the need to stay true to fans of the book and its author in her portrayal of Jones.

In one scene of the movie, Jones becomes a television journalist. Oddly enough, Zellweger herself was studying journalism in college. But she took an acting course as an elective, and surprised herself by falling in love with it. And apparently, she picked the right major. Zellweger just won a Golden Globe for her starring role in last year's comedy Nurse Betty.