The 'Skyscraper singer entered rehab last November for three months to receive treatment for her eating disorders and self-harming and believes by being open about her struggles, other people may be willing to seek help.
When asked why she's been so vocal about her personal issues, the 18-year-old star told AOL Music: "Because I know that if I can use my voice to speak to one person, or one family, then I've done my part. I feel like it's no coincidence that God put me through all of this and has also given me the voice that I have. I feel like my purpose on earth is much greater than just being a singer, a musician or actress. I think it's to reach out to people and to raise awareness of these issues that not many people speak about.
"I would love to see people get help for the issues that I've spoken about and see me as an example and say, 'Wow, there is a life outside of this addiction or this eating disorder.'
I think for me, if it prevents somebody from going down the path that I did, or if it saves someone's life because they choose to get help, then I've done my part."
Demi – who also suffers from bipolar – says while her problems are "ongoing" she is trying to get on with her life the best she can.
She said: "This is an ongoing process and the hardest part about these diseases is that they're things that I'm going to have to face every day for the rest of my life. I'm going to mess up and I'm not going to be perfect, but as long as I try everyday to get better and better myself, then I'm one step ahead of where I was before."