Bristol Palin is tanned, toned and ready to cha cha again for week two of Dancing With the Stars: All-Stars!

The single mom of three-year-old Tripp impressed fans and critics alike with her hot new figure on the September 24 premiere of ABC's DWTS, and as the fifteenth season heads into its second week, Palin is having fun flaunting her slimmer self.

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On Sunday, Palin, 21, headed to rehearsal with pro partner Mark Ballas in L.A. wearing gray clingy short shorts that showed of her muscular legs and toned derriere.

Returning to the series two years after her season 11 stint on the show, Palin told Us Weekly she's developed a new-found confidence she hopes will take her all the way to the DWTS: All-Stars finale. And of course, a revamped diet and fitness routine have helped Palin (who placed third in 2010) whittle her middle.

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"I'm definitely in better shape than I was last time, definitely. I'm just more active and I cut all the crap out of my diet! It's that simple," Palin said after DWTS judge Carrie Ann Inaba declared her the "most improved" returning contestant. "And my kid's a lot more rowdy, a lot more active. I'm running after him a lot! He's huge! He thinks he's a teenager already."

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Palin's partner Ballas has definitely noticed an improvement in his celeb's work ethic. "Mark says he's like a chimpanzee and I'm like a turtle, poking out of my shell!" Palin has said.

This article originally appeared on Skinny Bristol Palin Shows Off Amazing Legs, Booty at DWTS Rehearsal