Why Renee Zellweger wanted to pile on the kilos for Bridget Jones but was forced to compromise

Renee Zellweger famously gained 15 kilos for the original 2001 film, Bridget Jones's Diary, but has been talked out of gaining weight for the most recent film Bridget Jones's Baby.

Renee Zellweger intended to pile on the kilos a third time to play Bridget Jones more than 15 years on, but director Sharon Maguire talked her out of it.

"Sharon was hoping we could show that Bridget had achieved her ideal weight, but at the same time it didn't mean her life was perfect," said the Texan actress who famously gained 15 kilos for the original 2001 film, Bridget Jones's Diary and then did it all again in the sequel, The Edge of Reason, three years later.

"I wasn't sure about that one though because we all have something we think is wrong, that needs fixing, that in our own minds represents the ideal that we are meant to obtain. And I like the idea that that stays with us throughout our lives."

Zellweger's comments gain extra traction in light of constant media speculation about changes in her facial appearance over the years. The Oscar-winning actress, who travelled to Sydney with long-time partner Doyle Bramhall II, however, has repeatedly denied having plastic surgery.

She and Maguire found a compromise to Bridget Jones's weight issue in the form of a large prosthetic belly - in Bridget Jones's Baby, the serial singleton falls pregnant shortly after her 43rd birthday.

There's a 50 per cent chance Colin Firth's taciturn lawyer, Mark Darcy, is the father.

It's just as likely that Bridget Jones's baby belongs to the American dating guru (Patrick Dempsey) she hooks up with at a musical festival.

But it's just as likely that Bridget Jones's baby belongs to the American dating guru (Patrick Dempsey) she hooks up with at a musical festival.

Judging by his performance at a pink-carpet fan event for Bridget Jones's Baby in Sydney, playing a dreamboat comes naturally to the Grey's Anatomy star, who when he isn't acting, races cars.

"He practices every day," said Zellweger, hooting with laughter.

"He wakes up in the morning and works on his dreamboat chops."

Dempsey, however, addresses the question of his swooning fans with the sort of thoughtfulness one might expect from a real-life McDreamy.

"It's wonderful to get the emotion and the openness and warmth from people. That is something that is really moving to me," he said.

"Because the characters that I have played are a certain archetype, it's easy for people to project that onto - either the McDreamy character or the character in this film.

"You want to live up to that. I think it forces me to work on myself and to try and be that person."