Someone dance Kelly Osbourne right over to the craft service table!

The reality star, 25, has dropped 20 pounds as a result of her stint on Dancing With the Stars, but not without sacrifice, she says.

"I'm f------ starving right now!" Osbourne told backstage at Monday's performance show in Los Angeles, where Osbourne and her partner Louis van Amstel earned rave reviews for their '60s-inspired jive.

And though she's hungry, Osbourne's svelte new bod is turning heads. Van Amstel, who has helped the now size-2/4 Osbourne waltz her way into the final five, can definitely see the change in his partner's figure.

"Honestly she looks more like she lost 30 or 35 [pounds], she's fading in front of my eyes!" the pro tells Us. "I feel like she's a new person!"

Is Osbourne -- who admitted last summer that dancing "absolutely terrified" her -- nervous going into Tuesday's elimination show? Not really.

Watch Osbourne's competitor, Mya, in rehearsal for the show with partner Dmitry Chaplin.

"I've already proved myself, and I've had the best time I could possibly have and we've showed how hard we worked," she tells Us. "We're in the final five and no one takes it lightly. At the end of the day, we've all won."