media_removed_toofab 2013

Kim Kardashian
and her big sis Kourtney are on a mission -- not only to shoot a new season of "Kourtney and Kim Take Miami," but to also drop some weight!

The sisters were spotted working out on the beach in Florida on Wednesday, Kim showing her curves in a low-cut, black tank and pants, Kourt in a yellow sports bra, blue sheer tee and black cropped pants.

Kourtney, 33, looks great after giving birth to daughter Penelope back in July, while Kim, 31, admits to needing to shed a few pounds. 

“I’m hoping to slim down a little bit, and I’m not afraid to say it,” the reality star tells Life & Style, on newsstands now.

“I think everyone goes up and down in whatever that comfortable love relationship phase is where you like to eat out, but now it’s time to get it together again.”

Kim has reportedly gained 15 to 20 pounds since she began her relationship with Kanye West back in April, and she thinks it's time to get back on track.

“I’ve started QuickTrim again,” she revealed to the mag. “When I start that, it’s full focus.” 

So far she's doing pretty well! Kim tweeted that she's already lost 6 pounds, though is feeling a little embarrassed that she and her recently-preggo sis have the same number to shed:

"How is it that @KourtneyKardash & I have the same amount of weight to lose but she just had a baby! SMH help! LOL "

Click "Launch Gallery" above to see more shots of the Kardashian sisters during their beach workout!

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