Tammin Sursok ate "half a pack of rice thins and five cups of coffee" a day at the height of her eating disorder.
The 'Pretty Little Liars' actress admitted she spent eight years putting herself through "torture" in a bid to keep her weight down in a quest for perfection in response to being bullied as a child because she was overweight.
She shared an old photo of herself smiling on Instagram and wrote: "This was the height of my eating disorder. That day I had eaten half a pack of rice thins and 5 cups of coffee. That's what I had lived on for almost 6 months prior.
"I remember how sad I felt. Ha. Pictures lie, don't they?
"I was dying to be perfect. The illusion of perfection that one cannot attain.
"For perfection is a road that never reaches a destination. I was not well for 8 years. 15yrs old - 23 years old. 8 years of torture I put myself through to remain slim after I had been tormented as an overweight kid.
"For I feared that if I went back to that then the emotional pain would be worse than the physical one I was putting myself through."
The 35-year-old actress - who has Phoenix, five, and Lennon, six months, with husband Sean McEwen - urged people to open up about their struggles as everyone has their own demons and secrets make things worse.
She continued: "Your secrets make you sick. And I believe the more we talk about our truth the less isolated we become. We start to heal. The grass seems greener on the other side because the grass is fake. No one is walking around without demons. Remember that. For being human is being flawed. And when we embrace those imperfections we ARE "perfect". Because we are our truth."
Tammin ended her post on a positive note and admitted she has "never looked back" since she hit "rock bottom" and knew things had to change.
She wrote: "If you are going through something like I did, know that you can get better. At 23, I hit rock bottom. I stopped wanting to be sick. And I've been healthy every day since. Never looked back."