Khloe Kardashian: I Lost 20 Pounds!

Her sister Kim may be the one with the famous figure, but this time, it's Khloe Kardashian who is showing off her svelte new shape.

"I recently just lost 20 pounds!" the reality star told Usmagazine.com at the Three-O Vodka Bubble launch party in NYC Thursday.

See how more stars have slimmed down this summer

How'd she do it? "I try to do just 30 minutes of cardio, mandatory," Khloe, 25, tells Us. "Obviously if I have more time, I want to do weights, but really that cardio is what works for me because I'm bigger. Cardio is what leans me out, and it still works your muscle definition too. Any kind of cardio." And to avoid a monotonous routine, she makes sure to switch hers up.

See photos of stars' before and after bods

"I do different kinds everyday because I get really bored. I do boxing, I go on hikes, I do stairs," she says. "I'm always switching it up." Khloe -- who will appear with sister Kourtney in the new E! series, Kourtney and Khloe in Miami, this August -- is more than happy with how far she's come. "It's hard work, but it's worth it, and once you start seeing results, it keeps you motivated," she says. "Now I actually get excited. I'm like 'I've got to start seeing arm definition soon,' so I go to the gym."

See photos of Us' weight winners from last year

Besides her workout routine, the Keeping Up With the Kardashians star tells Us her dieting secrets. "I eat whatever I want until noon. Then from noon on, I watch what I eat," says Khloe, who adds that she is also launching a diet product called Quick Trim with Kim. "I only drink champagne. 100 calories in a glass, and I'm good."