Weight has long been an issue in opera. Where do you think the time-worn expression "It ain't over 'til the fat lady sings" comes from?Star soprano Deborah Voigt was at the center of a flap several years ago when she was removed from a London production of Ariadne auf Naxos because she couldn't fit into "a little black dress" the director wanted her to wear. Voigt later had gastric bypass surgery, lost more than 100 pounds and continues to have an international career.Indra Thomas, also an opera soprano, faced a similar turning point a year ago. "My health was an issue," she said. "I've been on yo-yo diets before. Every diet out there, I probably did it. I know I'm one of those emotional eaters. I knew I had to do something that would help me to stay on track, as opposed to trying to stay on track myself. I was borderline high blood pressure. I was borderline diabetic … all things that run in my family, and in my (African-American) culture as well. Every time I went to see my doctor, she was putting me on a new medicine."Next weekend, Thomas is the soloist in Samuel Barber's Knoxville: Summer of 1915 with the Florida Orchestra. When I spoke with her in February, she was in London, singing the title role in Verdi's Aida at Royal Albert Hall.Last May, Thomas had weight-loss surgery at Lenox Hill Hospital in New York (the same hospital where Voigt had hers). "Not the bypass or the Lap-Band surgery," she said. "The one I had done was called sleeve gastrectomy. It's a stomach stapling procedure. It's all done arthroscopically, which is nice. They cut your stomach vertically, and they leave you with a smaller stomach, and take the rest of it out. I felt this was a better procedure. Less invasive. Like taking out an appendix or gallbladder."Before the surgery, Thomas weighed more than 300 pounds. "Now I have lost somewhere around 70, 75 pounds," said the soprano, who is 5-foot-8 and in her early 40s. "With this surgery, you go down, but you don't go down very fast. Because of what I do for a living, I have to go down very, very slowly, because I have to retrain my body and my muscles to work for me, because that's what I use to sing with. This surgery takes you down slowly. With bypass surgery, people go down very fast. For an opera singer, that could be devastating to your system."Thomas has cut out spicy foods and carbonated beverages from her diet. Otherwise, she can eat as before, only less. "If I go out for dinner, I'll order an appetizer, and that will be totally enough and fill me up completely," she said.Her goal is to get below 200 pounds. "I don't want to be ultra thin," Thomas said. "That's not my personality anyway. And I really do have to have some weight on me to sing these big roles that I sing."Along with Aida, Thomas is often cast in other Verdi operas, like Un Ballo in Maschera and La Forza del Destino, as well as his Requiem. She frequently is a soloist in orchestra works, such as Beethoven's Ninth Symphony, and oratorios, such as Michael Tippett's A Child of Our Time.With the weight loss, Thomas has made some adjustments in her singing, but nothing dramatic. "My voice is pretty much intact," she said. "I haven't gained any higher notes, or lower notes. What has happened is that I feel I can move more smoothly through my passaggio now than I could before." (Passaggio is the Italian term for the transition point between vocal registers, like that between the chest voice and the head voice.) "I feel better about my movement on stage now because I'm lighter."Going public about her surgery takes some bravery. Voigt has occasionally been pummeled by reviewers since she did. Some have said her voice doesn't sound as good with the weight loss. Thomas said she tries not to read reviews. Her notices in London were fine, with Financial Times critic Richard Fairman writing that her performance was "vocally wayward but came good at the end" and George Hall in the Guardian saying her Aida was "imposing and often exciting, if uneven."Knoxville: Summer of 1915, with a text taken from a short story by James Agee on growing up in the Tennessee city, reminds Thomas of her own childhood in Atlanta. Her father, the late Rev. M. Emanuel Thomas, was minister of the Little Friendship Baptist Church of suburban Decatur, Ga., for 30 years. When the soprano was 19 and a music major at Shorter College in Rome, Ga., she and the church choir were featured in the movie Driving Miss Daisy. During a funeral scene, she was the soloist in a gospel version of What a Friend We Have in Jesus.Thomas and the orchestra perform at 10 a.m. Friday and 8 p.m. Saturday at Mahaffey Theater, St. Petersburg, and 7:30 p.m. March 18 at Ruth Eckerd Hall, Clearwater. The concerts, with music director Stefan Sanderling on the podium, also include Schumann's Symphony No. 1, Spring; and Copland's Appalachian Spring. $15, $30, $45. (727) 892-3337 or toll-free 1-800-662-7286; floridaorchestra.org.•••Sarasota Opera will perform the Verdi rarity Un Giorno di Regno in its 2012-13 season, announced last week. The composer's second opera, and a comedy (Falstaff was his only other comedy), Un Giorno di Regno (A King for a Day) will be the 29th entry in the company's ongoing Verdi cycle. Other operas during the 2013 winter season will be Puccini's Turandot and Carlisle Floyd's Of Mice and Men, both in new productions, and the return of Bizet's The Pearl Fishers. In the fall, the company will reprise its popular staging of Verdi's Rigoletto from 2008 and premiere a children's opera, Little Nemo in Slumberland, with music by Daron Hagen and libretto by J.D. McClatchy. Information: (941) 328-1300; sarasotaopera.org.John Fleming can be reached at [email protected] or (727) 893-8716.