Next week, the new Taylor Swift documentary Miss Americana will debut on Netflix. The film will reportedly feature the new song “Only The Young,” Swift’s attempt to write a political anthem for her generation. Earlier this week, we posted the trailer. Last night, Miss Americana held its premiere at the Sundance Film Festival, with Swift herself in attendance. And the film includes a revelation that Swift hadn’t made publicly before: She’s been dealing with an eating disorder.

According to The Guardian, there’s a segment in the film where Swift tells director Lana Wilson that she would often starve herself to the point where she’d sometimes feel like she was about to pass out during live shows. She discusses being hyper-critical of her own body: “I tend to get triggered by something, whether it’s a picture of me where I feel like my tummy looked too big, or someone said that I looked pregnant or something. And that will trigger me to just starve a little bit, just stop eating.”

Swift reportedly says this during the movie:

I don’t think you know you’re doing that when you’re doing it gradually. There’s always some standard of beauty that you’re not meeting. Because if you’re thin enough, then you don’t have that ass that everybody wants, but if you have enough weight on you to have an ass, then your stomach isn’t flat enough. It’s all just fucking impossible.

Swift has previously spoken about having body-image issues, but this is the first time she’s straight-up said that she’s had an eating disorder. She also reportedly talks, in the film, about regretting her decision not to speak up against Donald Trump doing the 2016 election. There’s apparently a whole thing where she goes against her father’s wishes when she releases her statement criticizing Marsha Blackburn, then a Republican Senatorial candidate in Tennessee. (Blackburn still won.)

Miss Americana will stream on Netflix 1/31.