Jennifer Aniston can lose 5lbs in five days.
The 'Bounty' actress follows a special regime whenever she wants to look particularly svelte, and is able to lose a dramatic amount of weight in a short space of time.
A source on the set of 'The Baster', which Jennifer filmed earlier this year, said: "Whenever she wants to look her best, Jen does this strict diet so she's able to lose 5lbs in five days.
"She did it during her past few films and doesn't find it hard at all. I saw her eat pasta only once!"
The 40-year-old star has been sporting a more toned physique lately, and it has been claimed her new fitness regime has left her feeling better than ever.
The source added to Life and Style Weekly magazine: "She runs before filming starts. We were filming from 6am until almost 11 at night, and she had a great energy level the whole time. She was upbeat and smiley and never flubbed a line - and her body looks amazing!"
It was recently claimed Jennifer, who is currently filming 'The Bounty' in New York, works out at 3am every day to ensure she stays in tip top condition.
A source said: "Jennifer has had a totally overhaul for this film. She wants to be seriously fit, yet remain curvy.
"There are a lot of early starts on set, so she has had to get up at 3am to get two hours in the gym before filming at 5am. She is supposed to be playing a 35 year old, and is concerned she won't look the part.
"It hasn't been easy, but she has combined one-on-one yoga sessions with gruelling weight and workout sessions."
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