To show off her newly slimmed-down figure, Kim Kardashian opted for some super-luxe, super-expensive pants to wear on her lunch date with her brand-new boyfriend Kanye West at Serafina in NYC Wednesday.

The Keeping Up with the Kardashians star worked J Brand's black lambskin leather "Quatro" pants, which feature zippered pockets on the front and back and at the ankles.

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She paired the bottoms -- which retail for a whopping $1,495 at -- with a crisp white blouse, a peach blazer and black heels.

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Last month, the star, 31, told Us that her single status -- which is a thing the past as of this week -- has made her want to slim down.

"I'm on a mission," Kardashian said, while adding that she shed six pounds in just seven days.

PHOTOS: Why 2011 was a struggle for Kim

The QuickTrim spokeswoman (who trains with Gunnar Peterson) did it with major devotion, working out two times daily -- early-morning treadmill runs and strength training or Pilates at night. Her workout buddy? Brother Rob Kardashian!

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