Taylor Swift revealed she once struggled with an eating disorder.

In her upcoming Netflix documentary Taylor Swift: Miss Americana — which premiered at the 2020 Sundance Film Festival on Thursday night (January 23) — the Lover hitmaker said that seeing unflattering paparazzi photos of herself triggered her need to lose weight, admitting she used to "starve" herself.

"It’s not good for me to see pictures of myself every day," Swift says in voiceover.

“It’s only happened a few times, and I’m not in any way proud of it," she explained, according to Variety. "A picture of me where I feel like I looked like my tummy was too big, or... someone said that I looked pregnant... and that’ll just trigger me to just starve a little bit — just stop eating.”

The 30-year-old pop star also described her relationship with food as "unhealthy."

"My relationship with food was exactly the same psychology that I applied to everything else in my life: If I was given a pat on the head, I registered that as good," she told Variety in her February cover story.

"If I was given a punishment, I registered that as bad," she said.

Swift went on to share the story of the time a tabloid magazine published a headline asking if she was pregnant — and how it affected her deeply. "I remember how, when I was 18, that was the first time I was on the cover of a magazine," she shared with the outlet. "And the headline was like ‘Pregnant at 18?' And it was because I had worn something that made my lower stomach look not flat. So, I just registered that as a punishment."

She said it didn't help that she'd be praised when she fit into sample size clothes on the set of photoshoots. "And I looked at that as a pat on the head,” she explained. "You register that enough times, and you just start to accommodate everything towards praise and punishment, including your own body."

"I think I've never really wanted to talk about that before, and I'm pretty uncomfortable talking about it now," Swift continued. "But in the context of every other thing that I was doing or not doing in my life, I think it makes sense to have it in the film."

Taylor Swift: Miss Americana is available to stream starting January 31.

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