By Sandra Gonzalez

CNN

(CNN) -- A "Pretty Little Liars" star got candid about her history with mental illness in a new essay.

Troian Bellisario has spoken about her past battles with an eating disorder, but in a piece published on Tuesday in Lenny Letter, she opened up about how bad her struggles once were.

"There is a part of my brain that defies logic," she writes in the latest edition of Lenny Letter. "Once, it completely convinced me I should live off 300 calories a day, and at some point, it told me even that was too much. That part of my brain is my disease, and there was a time when it had absolute authority over me."

Bellisario recently released a film called "Feed," that was in part inspired by her battle with and recovery from anorexia.

"It almost killed me, and you can see that even though I have lived in recovery for ten years now, it still finds loads of fun, insidious ways to thwart me to this day," she wrote. "It was a difficult journey finding my way back to health. Through hard introspection, intense medical and mental care, a supportive family, friends, and a patient and loving partner, I survived, which is rare."

The essay also dives into her ongoing struggle to practice self care, as told through an anecdote about a recent experience at a freezing lake, where she ignored her physical needs, gave into her desire to live up to her expectations for herself and did three laps in the bitterly cold water.

"As someone who struggles with a mental illness, my biggest challenge is that I don't always know which voice inside me is speaking," she writes. "My body voice, the one that says, Troian, I'm cold, get out of the lake, or my illness: You told everyone three times, so you can't disappoint them. You are not enough. Who cares about the difference between two times around and three? I do."

Bellisario's "Pretty Little Liars" recently wrapped up its seven-season run on Freeform.

The actress was recently cast in an upcoming film from director Richard Linklater starring Cate Blanchett and Kristen Wiig called "Where'd You Go, Bernadette?"