Kim Kardashian sleeps in her gym clothes.

The reality TV star - who is famed for her well-rounded butt - is so determined to keep in shape she goes to bed wearing exercise outfits so she can't avoid working out when she wakes up.

She wrote on Twitter: "Is it weird if I sleep in my workout clothes so I can get up early at 6am and work out? It will force me to and save time!"

Kim, 28, also admitted she is constantly battling cravings for sweet treats and baked a huge coffee cake to satisfy her urges.

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She said: "I'm baking a coffee cake right now! yummy! After a long day of hard work I need just one bit! I won't eat it all, I promise (sic)!"

However, after spending time making the dessert Kim only allowed herself to eat a tiny morsel because she is worried about piling on the pounds.

She revealed on the blog: "I had one bite to satisfy my craving, that was it!"

"Coffee cake was yummy, but a moment on the lips is a life time on the hips!"