Jordin Sparks attends the screening of "Sparkle" on August 14, 2012 in New York City. Credit: Andrew H. Walker/Getty

Jordin Sparks didn't need an over-the-top sequined gown to shine at the Sparkle premiere in NYC Tuesday.

Instead, the film's star, 22, donned a minimalist, alice + olivia by Stacey Bendet peplum frock (with matching patent leather stilettos) which showed off her incredible 50-pound weight loss.

At the Teen Choice Awards last month, Sparks opened up to Us Weekly about the key to her jaw-dropping body makeover, which she first debuted last spring.

"There is no secret," the Season Five American Idol champ shared. "It's just better eating and working out! It's definitely a daily thing."

One of her favorite ways to stay active? High-energy dance classes like Zumba.

"My mom's best friend is a Zumba instructor and I loved it," she gushed. "I started with walking then went to jogging and then Zumba." In addition to her cardio-heavy classes, "I started [working with a trainer] and we did 30 minutes of circuit training," Sparks says. "So I didn't feel like I needed to be in the gym for two hours."

Sparks' lifestyle changes have paid off big time -- this summer, the pop star landed the August cover of Shape, where she flaunted her slimdown in a barely-there bikini.

"I could only dream of having a cover and looking like that," she told Us. "I thought, 'I did it!' I had to walk back to my dressing room and . . . pull myself together because I was overwhelmed. I cried. I shed a little tear."