An appearance at the Oscars prompts many stars to exercise and diet ahead of the body conscious ceremony.

But it appears that actress Renee Zellweger may have taken things a little too far as she paraded her super-skinny figure outside the Kodak Theatre.

Painfully thin Renee, who was not nominated in any of the categories this year, made an effort to outshine this year's nominees in a glamorous silver and white rhinestones studded gown.

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Shrinking assets: Renee Zellweger looked incredibly thin on the red carpet at the Oscars in Hollywood today

Accessorised with vintage diamond Cartier brooches, she certainly looked every inch the modern Hollywood star as she graced the red carpet.

But it was her thin, bony appearance which drew much of the attention, for all the wrong reasons.

Renee's knobbly shoulders were exposed in the strapless silver sequined sheath by Carolina Herrera, a red carpet favourite for the actress, and the stunning gown was in danger of being upstaged by the skeletal frame it adorned.

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Fat-free: Renee's ultra-slim look exposed her knobbly shoulders and sinewy arms in her stunning Carolina Herrara gown

As Bridget Jones might have written in that famous diary, Miss Zellweger is looking v. v. thin.

The 38-year-old famously gained two stones to play Bridget Jones in 2001 - and fans at the time celebrated the fuller-figure look.

And for her role in Bridget Jones's Diary and the sequel The Edge of Reason, Miss Zellweger deliberately piled on the pounds by gorging on pizza, doughnuts and beer.

At the time, she said: "One doughnut does not do a thing. You've got to eat 20 a day for at least five weeks to get results."

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Doughnut diet: Renee Zellweger deliberately piled on the pounds and gained two stone to play Bridget Jones in two films by gorging on pizza, doughnuts and beer

But within weeks of filming finishing, she was pictured showing off a size-zero figure.

Although she remains tight-lipped on the subject of her weight, she is said to follow a microbiotic diet of lean fish, rice and vegetables.

Added to this, she endures gruelling two-hour daily workouts with a personal trainer.

The famously private star refuses to be drawn on her dietary habits.

"It saddens me every day when people come up and say, 'OK, how did you lose that weight?'," Renee said after playing the eponymous Ms Jones the first time round.

"I can't speak about it because I am not an authority on weight loss. I am just not.

"I am not challenged with a medical situation that's weight-related and that I need to pay attention to".

The actress was at the ceremony to present an award.

Later backstage she was seen with her silver Christian Louboutins slung over her shoulder. Actor Johnny Depp said: "I like your shoes.

"Thanks man," Zellweger replied, "I used to like the shoes."