Mariah Carey officially has her groove - and boy - back.

Six months after welcoming twins Moroccan and Monroe, the singer has lost 30 pounds, which she shows off in a big way on the new cover of Us Weekly.

"I just gained an enormous amount of weight," Carey says of the twin boy and girl she welcomed April 30 - her wedding anniversary with spouse Nick Cannon.

Looking at the short shorts and toned belly, that's a distant memory now ...

In July, Carey buckled down with a nutritionist and a workout plan from Jenny (formerly Jenny Craig), keeping to 1,500 calories a day and thrice-weekly workouts.

"I feel incredible," she says, just three months after her body transformation began. "It was just the biggest blessing to be able to have the babies," Carey adds.

"But I felt trapped in my body because I couldn't move." But now, she says, "I'm proud of how hard I worked to get my body back... I had to do this for me."

We'd say she did a heck of a job. You go girl!