The actress, who played Lady Sybil in the award-winning costume drama, said she has been living with her eating disorder since she was 14.
"I felt so alone for so long, and I just hid," she told The Daily Telegraph. "And then I started talking and held my head up, and instead of saying ‘sorry’ decided to tell myself that I matter."
Brown Findlay, 27, who is now starring in a new period drama Harlots, which is coming to Hulu in the U.S., explained that therapy sessions had helped her to open up about her disorder.
She added, "It’s about learning to stand up and say, 'This is me, and that’s OK.' I'm not going to be a better actor if I'm a dress size smaller. It's nothing to do with my brain."
She also explained that she has decided to speak publicly about her eating disorder to help others who find themselves in a similar position.
"If you are lucky enough to speak and be heard, it might be something that could be useful to others," she told The Daily Telegraph. "The more we have brave discussions like that going forward, the easier it is to talk about things, and the less alone we can feel. It’s certainly made me feel less alone."
The National Association of Anorexia Nervosa and Associated Disorders estimates that over 30 million people of all genders and ages suffer from an eating disorder in the United States. It has the highest mortality rate of all mental illnesses.
If you are struggling with an eating disorder and are in need of support, please call the National Eating Disorders Association Helpline at 1-800-931-2237. For a 24-hour crisis line, text “NEDA” to 741741.