Actress takes getting into character to limit

Rebecca Gibney (centre) plays slightly nutty mother Shirley Moochmore in the PJ Hogan-directed movie. Photo / Supplied

Rebecca Gibney came within an inch of being a diabetic after suffering a health scare while making the Australian comedy Mental.

The New Zealand-born actress admits now her "at all costs" attitude when she auditioned for the role of Shirley Moochmore in the PJ Hogan-written and directed film almost had a dire consequence.

The 47-year-old says she made it clear to Hogan that she wanted the part, knowing it would be the biggest role she has ever had - despite her lengthy acting career.

"When I auditioned for the role, I said that I would stand on my head, I would do whatever it takes, put on weight, because I wanted this role so much I would do whatever to get it," Gibney said.

"I've done small roles in features before but this is certainly the biggest feature film role I have had."

After being cast as the slightly nutty mother Shirley, Gibney set about gorging herself and doing next to no exercise to pile on the kilos to her fit frame.

Within two months, she was fast approaching her goal weight of an additional 20kg, but then noticed something was dreadfully wrong, health-wise.

After a visit to the doctor, she was told to immediately stop stacking on kilos.

"I was hoping for 20kg or as much as I could.

"I put on 14kg in eight or nine weeks and I found out towards the end of gaining the weight that I was insulin-resistant and pre-diabetic.

"I was one step away from diabetes so if I had put on more weight I would get diabetes.

"So I stopped and we decided to employ the use of a fat suit."

But she didn't immediately trim down.

She maintained her overweight figure for as long as she could during the shooting of the feature movie without further putting her health in jeopardy. "The double chin is all mine," Gibney jokes.

"PJ doesn't like tricks - he wants the characters to be real and likes actors to put on the weight."

Gibney has rarely been out of work in her acting career, mainly for TV roles, but since being cast in Mental she has become intoxicated with the thought of appearing in another feature movie.

She says one is on the horizon for early next year, but cannot name it for confidentiality reasons.

Gibney says television, such as Packed To The Rafters in which she appears as Julie Rafter, is an insatiable beast with little time to perfect a scene because of the chaotic shooting schedules.

It's one of the reasons she enjoyed shooting Mental because of the time spent filming and perfecting the scenes and performances.

"In television you get so little time to do anything, you are doing things on the run and maybe get an hour to do a scene.

"In film you get a whole day to a scene if you need it.

"I'm not under any illusion I am going to have a film career and if this is the last feature I ever do, I am going out on a high because it's such a wonderful movie and to be part of an incredible cast and working with PJ Hogan.

"If I never do another movie, I'd be happy."

Mental opens on October 25.

- AAP