Angelina Jolie plans on getting in peak physical condition for her latest role in Salt through an intense detox diet, it's claimed.  

The Changeling star reportedly wants to shed 21ibs in 21 days via the use of Martha's Vineyard Detox Diet, so she can appear lean and muscular as Evelyn Salt in her upcoming movie.

For once we see a not-so-glamorous Angelina take on a multitude of disguises - one which includes a man - to play a CIA agent who is on a mission to clear her name. 

A source tells Grazia magazine, "To play a man convincingly Angelina is adamant she needs to lose her curves.

"She has been trying to go for the full 21 days but it's tough. She's lost around eight pounds but is now introducing a couple of small meals in between shakes as she was starting to feel weak."

Angelina as Evelyn Salt (Splash News)

But it seems that Angelina's extreme diet could be having a knock on effect in the Brangelina household.

The source adds, "Brad told her that if she was staying on the diet, he was getting out of the way. Then she started screaming at him about a chore.

"He felt that whatever he did or said would be wrong, so he went to Los Angeles to let off steam with some buddies. He thinks the diet is dangerous and unnecessary."

See Angelina on the run in Salt below