The actress, who plays Rachel Breckle, was admitted to a residential adolescent unit psychiatric ward for three months aged 11 when school bullies drove her to developing an eating disorder.
Oaten told The Sun; "I was at my worst then. I'd have five cornflakes and a sherry glass of water a day."
She attended another unit for six months at 14 after falling ill again. Oaten was then hospitalised while on the verge of having a heart attack aged just 17.
She finally overcome the disorder when a close friend, who had been her first boyfriend, committed suicide.
"I thought, 'What am I doing?' I was basically killing myself too. I owed it to my parents to change."
Oaten, now 27, saw a therapist and finally beat the illness when she was 22. She then pursued her dream of becoming an actress.
"[Emmerdale is] a dream come true, but I fought hard for it. Going through all that made me so determined. It took over my life and there were times I just wanted to die, but there was still some tiny bit of fight left in me."
Her mum Marg has since been awarded an MBE for setting up eating disorders charity Seed.
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