Demi Lovato believes only a few female music stars truly stand up for themselves.

The singer told Cosmopolitan in a new interview that herself, Rihanna and Nicki Minaj are the rare females in mainstream music that aren't afraid of telling people the truth.

She said: "There are a lot of girls in pop.

"They have badass lyrics, but I feel like I'm the only person other than Rihanna and Nicki Minaj who isn't afraid to say, 'Try something on me and I'll f**king beat your ass'. 

"There are people who can dress up and play the part, but their music doesn't say it."

Lovato's cover issue of Cosmopolitan will go on sale from August 11.

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