In an interview with Sunday Night promoting her upcoming Australian tour, the 21-year-old former Disney star opened up about her evolution from squeaky clean Hannah Montana to pot smoking, peroxide blonde, twerking pop star.

"Does it ever bother you that drugs could hurt your brain?" interviewer Chris Bath asked, referring to the Wrecking Ball star's 23^rd tattoo which reads, "Love your brain".

"Do you know what hurts your brain? Googling yourself. You know what hurts your brain? Instagram. You know what hurts your brain? Sitting there and reading the comments on Facebook. I have a 14-year-old sister and I go through her comments and people are calling her a slut and that's a 14-year-old. So I think that's hurting your brain," she said.

"I put pictures of me smoking weed, I'm not going to lie, on my Instagram because I was brought up in the way that we never thought marijuana was bad.

"I don't promote it in my songs or say it, it's not like I'm sitting around telling a bunch of kids to do a bunch of drugs," the singer with a social media fan base of more than 80 million said.

She also touched on her break up with Australian actor Liam Hemsworth. The couple broke off their engagement in 2013 before Cyrus released her fourth album, a project she called a "break up album", Bangerz.

"I love Liam and Liam loves me and it's about finding yourself and sometimes you have to separate yourself from everyone. I just had to become this person who is sitting in this chair right now. If I didn't I just felt like there was something that was going to explode and I had to set myself free," she said.

Since setting herself free, Cyrus has become renowned for her barely-there costumes. However, not wearing much has done wonders for her style cred within the fashion world. She regularly works with controversial photographer Terry Richardson, was cast by Marc Jacobs to front his Spring 2014 campaign and will feature in a fashion spread shot by Chanel creative director Karl Lagerfeld in an upcoming issue of V magazine.

"I've always been into fashion. I was brought up around Dolly Parton who was all tits ... and both my parents are covered in tattoos and are really cool. Wwhen they were teaching us how to be it was to become good people on our own. It was never, 'You should do this because if you don't people are going to think this way'," she said.

Cyrus also rejected claims that her now infamous performance at the 2013 MTV Video Music Awards with Robin Thicke exploited women.

"No one talked about him or what he was doing, it was all my fault. It's funny, I just never thought anything about it. Literally, I never thought 'Oh this is like a married dude that I'm dancing with this way'.

"Elvis, he wasn't wearing the outfits I was wearing but he was twerking. He was a symbol of sex but no one would have ever called Elvis a slut because he wasn't a girl. It's that double standard and I think I'm doing something for that double standard of women being able to represent sexuality as much as men and not being called names for it," she said.