Demi Lovato was ''super jealous'' of Miley Cyrus.

The 22-year-old beauty has admitted she envied the 'Wrecking Ball' hitmaker for her ability to party all the time but insists she's learnt not be ''bitter'' about it.''

She told Cosmopolitan magazine: ''There was a time when I was jealous of people who were able to party. For instance, Miley - in her music video '[We] Can't Stop,' her whole thing was partying and not giving a f**k.

''Part of me was super jealous that I couldn't be like that. I had to look at my life and be like, 'Okay, that's just not what you can do. There's no need to be bitter about it.'''

Meanwhile, the 'Skyscraper' hitmaker - who has been open about her bulimia and self-harming in the past - has previously revealed she has hit ''other rock bottoms'' apart from her stint in rehab.

When asked if going to rehab was her rock bottom, she said: ''With my eating disorder, yes. With my mental health, yes. But I also hit other rock bottoms after that and that's because I didn't keep my treatment on-going.

''Every day I have to remind myself that I have an addiction and that I have suffered in the past from an eating disorder and that I have to take the steps that are required for my bipolar disorder in order to live a healthy life. It is not something that I forget about.

''I've actually learned how to overcome those feelings without drugs and alcohol now, which is awesome, and I now live well and I'm very happy even though I have bipolar disorder.''