Vanessa Hudgens gave a bold performance in "Gimme Shelter," as she gained weight and cut her locks. But Vanessa Hudgens said the transformation was also a cause for 'concern' from her best friend.

Vanessa Hudgens plays a downtrodden, pregnant teenager in "Gimme Shelter," out in theaters on January 24.

Critics noted her impressive immersion into her character, Apple, from the weight gain and the boyish haircut, to "the way she carries herself, the entirety of her mannerisms, her very presence on the screen. She's boyish, zitty, hunched over, and profoundly closed off. It's easily the most effective part of the entire film," according to film.com.

But in an interview, Vanessa Hudgens confessed that her best friend was concerned about what the film was doing to her. At one point, she claimed that "Gimme Shelter" nearly destroyed her as she didn't really know who she was anymore.

"Vanessa was gone. I came home and I was a complete disaster," she said as reported by contactmusic.com.

Vanessa Hudgens also said that to this day, her best friend is still so worried about her when she thinks about that period.

"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,'' she added.

"My best friend tells me all the time how she was so concerned about me, because, she, for the first time, looked into my eyes and she didn't see me," the "High School Musical" star said on E! 

"She saw someone who was really broken down and had very low self-esteem. So it took a lot of work. It was good because it made me that much stronger and I have to give myself a pat on the back for going that deep," Hudgens said.

She then went on to say that hair extensions were a lifesaver, as they gave her an "instant confidence boost" while she dealt with the insecurity brought on by the weight gain and messy haircut.