The 'Heart Attack' hitmaker, who sought treatment in rehab for "physical and emotional issues" in October 2010, admits she used to shun the responsibility but now realises it's important to set a good example for her younger fans.
The 21-year-old 'The X Factor' USA judge told Entertainment Weekly magazine: "That was my excuse to do whatever the f**k I wanted and not give a s**t about what other people thought. Then I ended up going through some stuff. I realised I'm never going to escape the fact that I'm in the public eye, so I might as well do the best I can."
The former Disney star credits her fans for helping her get through her toughest moments over the past few years.
She said: "When I was in treatment, I honestly thought my career was over. But when I came out of treatment, I had more supportive fans than ever."
But the brunette beauty supports her close pal, Miley Cyrus, who has been criticised for being a bad role model after a string of controversial performances.
She said: "She's having fun and figuring out who she is, and this is the age when that happens. I think that... she's doing her own thing. Good for her."
Demi is set to release a book of daily affirmations, 'Staying Strong: 365 Days a Year' next week and has also signed a deal to write her memoir.
She said: "I'm battling with internal thoughts on how honest I should be. Yes, I've been very honest, but if people really knew how dark and deep my struggles got -- not just with my eating disorder but with drugs and alcohol -- they'd be really shocked. But I'll most likely end up saying everything. Maybe it'll help other people in the industry who are headed down the wrong path."