It’s hard to believe Mariah Carey gave birth just six months ago, especially after seeing her on the cover of Us Weekly…

The 41-year-old part-Venezuelan songstress—who gave birth to twins Moroccan and Monroe in late April, who now have a dedicated website—shows off her slim physique and oh-so-toned stomach on the cover of  this week’s issue of the celebrity news and gossip magazine.

“I gained an enormous amount of weight,” the Grammy-winning superstar tells Us of giving birth to her son and daughter on April 30—on her third anniversary of her wedding to Nick Cannon.

So how did Carey lose the baby weight? Starting in July, she began working with a nutritionist to create a 1,500-calorie-a-day menu. And, she partnered with Jenny (formerly Jenny Craig) to create a three-times-per-week workout plan.

“I feel incredible,” says Carey, just three months after beginning her body transformation. “It was a huge blessing to be able to have the babies, but I felt trapped in my body because I couldn’t move.”

During a recent appearance on The Rosie Show, Carey—looking fierce in a black mini and leather jacket—opened up about her first week on the Jenny diet plan.

“It was just water, initially,” Carey told show host Rosie O’Donnell. “When I started with the program, I lost at least 30 lbs. of weight that needed to be lost.”

Carey says she never weighed herself while shedding the pounds.

“I would tend to go, ‘Does this size dress fit me that I wore three years ago? I’m good, let’s go,’” recalled Carey. “I would go by what it looked like, how I felt.”

And by the grin on her face on that Us cover, it’s easy to see she’s pleased with the results!

Images courtesy of Us Weekly and The Rosie Show/OWN.