Mariah Carey: I Lost 30 Pounds of Baby Weight in 3 Months!

 Wayne Maser

"Shake It Off," indeed!

Six months after welcoming twins Moroccan and Monroe, Mariah Carey has lost 30 pounds — and shows off her toned legs and flat stomach in size-6 short-shorts on the stunning new cover of Us Weekly, out now.

"I gained an enormous amount of weight," the Grammy-winner superstar tells Us of welcoming her son and daughter April 30 with hubby Nick Cannon.

How'd she slim down? Beginning in July, Carey buckled down with a nutritionist and a workout plan from Jenny (formerly Jenny Craig), keeping to a 1,500-calorie-a-day menu and thrice-weekly workouts.

"I feel incredible," the "Fly Like a Bird" singer tells Us, three months after her body transformation began. She and Cannon, 31, famously struggled to conceive their twins (born via C-section at 35 weeks) after a heartbreaking miscarriage.

"It was a huge blessing to be able to have the babies," Carey says, "But I felt trapped in my body because I couldn't move."

Adds the once-again svelte star: "I'm proud of how hard I worked to get my body back…I had to do this for me."

For much more of our cover story on Mariah's incredible transformation — her body ups and downs, a sample menu and workout plan, adorable new snapshots of the babies, what Nick thinks of her new body and whether she'll lose more weight — pick up the new Us Weekly, on stands Friday!

Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!

Want stories like these delivered straight to your phone? Download the Us Weekly iPhone app now!