Rihanna is unhappy with her tiny body.

Rihanna is unhappy with her size zero figure.

The 'Where Have You Been' singer has admitted to being a tiny UK size four but would prefer her fuller figure back.

She told Us Weekly: ''I'm a size 0 - and not happy about it! I went way too far. I prefer myself a bit chunkier. I want my old butt back!''

The 24-year-old is working on her seventh CD and is trying to squeeze in some more relaxation time.

But her jam-packed calendar is having a slimming effect on famous beach body.

The 'Battleship' star said: ''I want to do two more [movies] before touring again next year. My schedule is crazy!''

The Barbados-born beauty was recently admitted to hospital for fatigue following her appearance at the Met Ball last month.

She stunned audiences in a black, reptile-inspired Tom Ford gown but had fans worried about her shrinking frame.

She confessed: ''I got no sleep [beforehand]. It's harsh on your body!''

Experts have suggested that Rihanna may be suffering from narcissistic personality disorder while friends insist she is '''feeling lost''.

© Bang Showbiz