She rocked a sexy black dress and bombshell hair and makeup for Elton John's Oscar party on Sunday night, but Kim Kardashian looks just as stunning bare-faced and dressed-down.

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The 31-year-old reality star showed off her famous curves -- and toned tummy -- in just a sports bra and sweats in a photo she posted on Twitter Monday night.

"Sweatpants hair tie chillin' with no makeup on!" she wrote.

Kardashian can also be seen looking less glamorous than usual in the current issue of Allure.

"Kim is a natural beauty," makeup artist Fulvia Farolfi told the magazine. "So we wanted to show her as naturally as possible, like she had just come back from the beach."