|Vanessa Hudgens' make over for "Gimme Shelter"|
The 25-year-old actress' friends were left "concerned" for her when she wrapped the movie because she had immersed herself so much into the role of homeless pregnant teenager Apple, she had lost her sense of self and was in "a bit of a mess."
She said: "I didn't really know who I was - Vanessa was gone. I came home and I was a complete disaster.
"My best friend is still so concerned about me when she thinks about that day because I was just a bit of a mess. I wasn't really comfortable in social situations and my self-esteem was super low 'cause I had no hair and I had put on all this weight, so physically I didn't feel attractive. And I was single."
However, Vanessa had an easy way to feel herself again.
Asked what she did to return to herself, she told Flare magazine: "Extensions! Instant confidence boost!"
Vanessa - who gained 15lbs for the movie - cut her hair off on camera during filming and enjoyed the challenge of transforming herself to feel "grimy and ugly."
She said: "The grimier and uglier I got, the more I was like, 'F**k yeah.'"
And the actress got so into the role, she burst blood vessels trying to portray giving birth convincingly.
She admitted: "I popped a bunch of blood vessels in my neck and face from pushing so hard."