Size zero Rihanna wants to be 'chunkier'

Mario Anzuoni / REUTERS

By Us Weekly

Rihanna is running herself ragged.

The unattached, "Where Have You Been" singer, 24, is at work on her seventh CD -- and trying to squeeze in some more zzz's! Recently, she opened up to Us Weekly about her jam-packed calendar -- and the effect it's having on that famous beach bod.

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Recently, the pop diva made the leap from the recording studio to the big screen with her star turn in "Battleship." "I want to do two more (movies) before touring again next year," Rihanna gushed to Us of her filming experience, even though, "My schedule is crazy!"

So crazy, in fact, that the Barbados-born beauty was hospitalized for fatigue following her appearance at the Met Ball last month, where she stunned in a black, reptile-inspired Tom Ford gown.

"I got no sleep (beforehand)," Rihanna explained. "It's harsh on your body!"

PHOTOS: Rihanna, then and now!

Her hospitalization -- and her shrinking bod -- have some fans fretting that she's dealing with something more serious, though Rihanna assures Us her nonstop schedule is the only thing to blame.

"I'm a size 0 -- and not happy about it!" she says. "I went way too far. I prefer myself a bit chunkier. I want my old butt back!"?

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