Renee Zellweger: 'Putting on weight again for Bridget Jones 3 might kill me'

She is clearly tempted by the prospect but Renee Zellweger – like her most famous screen creation - has weight issues to deal with before she will play Bridget Jones again.

For her first two films as Helen Fielding's diary-writing singleton, Renee piled two stone on to her tiny frame and then rapidly shed the pounds afterwards.

Asked whether the health implications of such yo-yo dieting were a factor in reprising the role, Renee said: "You are not kidding.

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"Can I just tell you my body is whacked by the time we finish one of those.

"It doesn't know what has happened because it thinks there's supposed to be a baby and there's no christening."

She added: "Did you see that movie about fast food, Supersize Me?

"I had a panic attack with all the specialists talking about how bad this is for you, long term, putting on that much weight in short periods of time and they're all saying, 'You must stop this now or you're going to die'."

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But in Hollywood it's never wise to say never.

Asked about a third Bridget film, she said: "Maybe I will. It depends if it works into my life and if it's interesting."

She added that it would rely on Helen Fielding coming up with the material but then hinted she knew about a new diary being compiled around the author's life as a British mother in Los Angeles.

"It's really a Fielding question," said Renee. "I know I want to read the book. She's been married to an American and moved to LA and had a baby.

"I would love to hear her perspective, a British person landing in LA and becoming a mom, I think the hilarity in that is boundless."

Renee, who was speaking in New York, recalled the overeating she had to do to gain weight for the first film in 2001.

"It sounds like heaven," she said. "For two days it's bliss and then you're full, OK? And you can then indulge all your fantasies about over-eating.

"Fantasies about non-stop chocolate consumption or your fantasies about ordering the pizza and the spaghetti and the garlic bread.

"Then after a week your glucose levels are going crazy. You're up and down and all over the place. It doesn't feel good, and no one wants to hear that, but it's the truth."

Then there is the dieting afterwards. "It was horrible," said Renee. "On one side it's fantastic because you get to go back to taking care of yourself, so you feel wonderful, but the first lap around the track I felt like I had a toddler on my back."