Deborah Voigt is back, in black.

The American soprano returns to the Royal Opera House stage on Monday, four years after the company fired her for being too big to fit into the black evening dress chosen for the title character in Richard Strauss's Ariadne auf Naxos.

The decision sparked a ferocious debate about weight discrimination in opera. Now, a slimmer Voigt is back to perform the same role in the same opera — wearing "that" dress.

Deborah Voigt, seen here in 2006, called society's attitude toward heavy people 'the last bastion of open discrimination in our society.' (Stephen Chernin/Associated Press)

"When I got the call from my manager, I have to admit my first reaction was to laugh, because we had come full circle," Voigt said a few days before opening night.

"When that happened, I didn't anticipate ever coming back, because I didn't think they would invite me."

Voigt, one of the world's leading opera singers, had been scheduled to play the lead in the Royal Opera's summer 2004 production of Ariadne. But the casting director decided the titular Greek goddess should wear a black evening dress and believed Voigt would not look right in it.

"I was angry about it at the time and for quite a while afterwards," said Voigt, who once called the attitude toward heavy people "the last bastion of open discrimination in our society."

However, Voigt had gastric bypass surgery in June 2004, three months after the story broke, and subsequently lost 135 pounds. She says she had been considering the surgery on health grounds for years, long before the black dress incident.

"I didn't need the Royal Opera House to tell me I was fat," Voigt said. "I knew I was fat."

She now concedes she wouldn't have been right for the production and thinks opera's increased focus on image is here to stay.

'To assume that one can weigh 300-plus pounds and still be viable on today's opera stage is naive.'—Deborah Voigt

"I think that the face of opera is changing," Voigt said. "To assume that one can weigh 300-plus pounds and still be viable on today's opera stage is naive. I tell that to young singers.

"Opera has changed immensely in my generation, and it is going to change more."

In 2006, the Royal Opera rehired Voigt, announcing she would return to the role of Ariadne in the 2007-2008 season. Beyond that, the company refuses to discuss the incident, saying only that rehearsals have gone well and it is "looking forward with great excitement to Deborah Voigt's performances in Ariadne."

An ebullient Voigt seems to have put the episode squarely behind her. She has nothing but praise for her "warm and welcoming" reception by the Royal Opera and has poked fun at the furour by releasing a YouTube video entitled "The Return of the Little Black Dress," in which she and her slinky nemesis make up.

Voigt, seen performing here with Placido Domingo in March 2004, underwent gastric bypass surgery three months later. She said she had been considering the surgery on health grounds for years. (Richard Drew/Associated Press)

"It just seemed at the time that we weren't a good fit," the dress tells the now-svelte singer in the clip. "But times change; people change."

Voigt said in 2004 that she didn't expect to be allowed to sing at the Royal Opera House as long as casting director Peter Katona remained. He's still there, and the pair have reconciled.

"I remember that Mr. Katona said some day we would be able to laugh about this," Voigt said. "And I said, 'Yeah, right.' But he was right.

"There is no point walking around with a chip on your shoulder about it. Life's too short."

At 47, Voigt's career is going strong. Some have detected changes to her voice as a result of the weight loss, and Voigt acknowledges it has been an adjustment.

"Four years on, I am still having to rethink how I sing," she said.

But an Associated Press reviewer thought her recent performance in Tristan und Isolde at the Metropolitan Opera was majestic: "Her voice has lyric beauty as well as steel," the review said.

In 2011, Voigt is due to sing Bruennhilde in the Met's much-anticipated new Ring Cycle. Since her surgery, she has expanded her repertoire, playing Biblical temptress Salome and legendary beauty Helen of Troy.

"It's nice to be able to play the pretty-girl parts," Voigt said. "I never thought I would be able to do that."

Ariadne auf Naxos opens Monday at the Royal Opera House and runs until July 1.