Billie Eilish's issues with body image lead her to "disassociate" herself from her looks while performing.

The teen pop idol, who is known for wearing baggy outfits when performing or out in public, revealed how she feels different about herself on stage in an interview with The Guardian.

"When I'm on stage, I have to disassociate from the ideas I have of my body," she said. "Especially because I wear clothes that are bigger and easier to move in without showing everything - they can be really unflattering.

"In pictures, they look like I don't even know what. I just completely separate the two. Because I have such a terrible relationship with my body, like you would not believe, so I just have to disassociate..."

Speaking about her relationship with her body, Billie seemingly referring to an incident last year when she was snapped wearing sports shorts and a tank top.

"You get a paparazzi picture taken when you were running to the door and had just put anything on, and didn't know the picture's being taken, and you just look how you look, and everyone's like, 'Fat!'"

The Bad Guy hitmaker went on to explain how she doesn't understand the desire to scrutinise other people's bodies as, "we only need bodies to eat and walk around and poop".

During the wide-ranging chat, Billie also criticised stars who have plastic surgery and deny it for promoting unrealistic body image expectations.

"It's completely fine to get work done - do this, do that, do what makes you feel happy. It's just when you deny it and say, 'Oh, I got this all on my own, and if you just tried harder, you could get it,'" the 19-year-old raged. "That makes me literally furious. It is so bad for young women - and boys, too - to see that."

Billie released her second album, Happier Than Ever, on Friday.