Mariah Carey Poses in Bikini After Losing 30 Lbs. in Six Months

Unlike some new moms, Mariah Carey is more than happy to show off her post-baby body. The songstress, who gave birth to twins nearly one year ago, flaunts her abs on the May issue ofShape and reveals some of the weight-loss secrets that helped her shed 30 pounds in just six months.

While pregnant with Moroccan and Monroe, "I put on around 70 pounds," Carey, 42, tells the magazine. "But if you look at photos of me when I was pregnant, you'd say, 'Wow, she gained 9,000 pounds!' A lot of it was water weight because I pretty much had head-to-toe edema, which is very painful. Luckily, all the swelling went away fairly quickly after the babies were born. Then I had about 30 more pounds to drop. I have such empathy for people who need to lose a lot of weight, because I know what they're going through. I remember thinking at the time, 'I'll never look or feel the same again.'"

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Carey — who poses for the magazine cover in a bikini bottom and striped, off-the-shoulder top — selected Jenny Craig to help lose the rest of the weight because she liked the way their program, which she started last July, is structured. (She's a big fan of the brand's meals, especially the soups, but prepares a lot of her own food at home.) In November, it was announced she had become the company's brand ambassador and her first commercial aired in December. "I used to be able to slim down just by exercising more, but that's changed," she says. "Since having the babies, I realize that 90 percent of losing weight is my diet."

The singer, who says her weight has fluctuated 15 to 20 pounds over the years, still fits in her exercise time though. "Today my workout routine is more about getting and staying toned," she tells the mag. "And for me, that means either taking hour-long walks a few times a week or jumping in the pool three or four days a week to do 45 minutes of aquatic exercises… Swimming is my favorite form of exercise."

As for her exact weight, similar to Nutrisystem spokesperson Janet Jackson, Carey isn't telling. Last fall she explained to USA Today that she doesn't go by a scale — instead the 5'9" star measures by her "dress size. Right now I am between a 4 or 6."

The megastar isn't the only member of her household who has undergone a diet overhaul recently. Carey tells people that her 31-year-old husband, Nick Cannon, has revamped his life since he was hospitalized for kidney failure in January and then again in February with blood clots related to his autoimmune disease, lupus nephritus. "It was really frightening," Carey says of the incident, "but he's feeling much stronger and is definitely on the right track. "He's taking better care of himself, eating a diet low in sodium and sugar, and getting more sleep."

As for her own sleep patterns, Carey says having twins makes it a little more difficult, but she rolls with it. "My schedule has always been the opposite of most people's. I sleep during the day and wake up at 10 at night, which is why I've been able to adapt to the babies' schedule so well. I'm actually sitting here debating whether I should do a 10 p.m. or a 4 a.m. workout today. If I exercise in the morning, I'll be able to purée some pears and feed them breakfast."

Between the babies and her new diet and fitness plan, she's juggling a lot, but fans of her music will be happy to hear that she's made time for recording. "I've started writing songs for a new album, which I hope will come out in 2012," she says. "Getting back in the studio and making music again — which I truly love doing — is the best way to end this crazy year."