Mariah Carey: I Lost 70 Lbs. After Twins

Mariah Carey wasn't shy about showing off her baby bump when she was pregnant with now-6-month-old twins Moroccan and Monroe Cannon.

And now, she's positively ecstatic about unveiling her hot new post-baby body after losing, she says, a full 70 lbs.

On Tuesday's episode of The Rosie Show on OWN, Carey, 42, was lowered diva-style onto the stage riding on a crescent moon and wearing a skin-tight black mini-skirt and cleavage-baring leather jacket.

She then explained her new physique was courtesy of a strict diet and exercise – along with the loss of what she says is about 40 lbs. of water due to a difficult pregnancy.

"In the beginning, when I first had the babies, I had so much edema … water and swelling. Most pregnant woman have that just in their feet," Carey says. "One day I was doing my thank-you notes and I noticed it started rising up the leg, so I had edema. … I didn't think I would ever be the same person."

Diet Plan Spokeswoman

Once she'd shed the water weight, Carey embarked on the Jenny diet plan (formerly Jenny Craig), for which she now serves as a spokeswoman.

"The first week, I lost 40 lbs. … of just water," Carey says. "It was just water, initially. When I started with the program, I lost at least 30 lbs. of weight that needed to be lost."

And, says Carey, it wasn't all about appearance. Carrying so much extra weight made everyday tasks, including going to the bathroom, a challenge.

"I had a really tough pregnancy," she says. "I was supposed to be on bed rest, but it was so bad that even bed hurt. … I learned a lot being pregnant, watching my body change."

She adds, "The whole point of this is not just like: 'Oh, hey, look at me and my weight loss, I'm fantastic.' It's really health. Like I said, I learned it when I became helpless and felt so vulnerable like never before in my life."

How She Did It

Because she had a Cesarean section, Carey says exercise wasn't an option early on. So, she says, "The diet is 90 percent of it."

Remembering to eat was one of her biggest challenges because, she says, she believes if she goes too long without refueling, "You slow down your metabolism."

For her, it was important "being able to just grab something. I like the soups a lot. It's 50 calories. I gotta say I like the snacks too."

Carey also regained her fitness by exercising with her dogs and doing workouts in the ocean.

One thing she won't stick with once she meets her goal.

"I never weighed myself," she explains. "People will think I'm a liar but it's true. This is another cliché phrase, I'm a big boned girl … I'm tall and so I always weigh more."

Instead of weighing herself, she says, "I would tend to go, 'Does this size dress fit me that I wore three years ago? I'm good, let's go.' I would go by what it looked like, how I felt."