Demi Lovato has praised her friend Iggy Azalea's "very outspoken" nature.

The Sorry Not Sorry singer has been long been open about her struggles with depression, drugs, alcohol and eating disorders, but following a successful stint in rehab, she's now focused on keeping a healthy mindset and surrounding herself with a solid support system.

In particular, Demi has credited rapper Iggy with being one of the people she can count on.

"She’s super low-key; she doesn’t drink or party. She has struggled a lot. ‘No money, no family, 16 in the middle of Miami,'" she told Billboard referring to a lyric from Iggy's 2014 debut album, The New Classic. "She’s very outspoken, and sometimes it can turn people off. But that’s one of the reasons I love her. She’s not the type of person who lies to you.”

Another celebrity Demi appreciates is Adriana Grande, who she describes as "super chill". And the star is looking forward to spending time with singer-songwriter Kehlani and hip-hop star DJ Khaled on her Tell Me You Love Me World Tour, which kicked off in February.

"You kind of think, 'What does he do?' But he plays his hits and does his dance and engages with the audience so much," the 25-year-old said of Khaled. "It’s just so much fun to watch him."

In the lead-up to her gruelling trek, which includes stops across North America, Latin America and Europe, she has been working with a nutritionist and trainer to get fit. But she warned fans not to expect the same super sexy outfits she has worn for previous shows.

"I think I’m going to wear an oversized hoodie and boots," she smiled, "I really honestly don’t give a f**k. That’s not why people come to my concerts anyways."