Up to 24 million men and woman of all ages suffer from an eating disorder — and actress Zosia Mamet (Girls, Mad Men) is one of them.

In the September issue of Glamour, Mamet, also a columnist for the magazine, opens up for the first time about the eating disorder she’s been fighting since someone called her fat at age 8.

“I'm not fat; I've never been fat. But ever since then, there has been a monster in my brain that tells me I am — that convinces me my clothes don't fit or that I've eaten too much,” Mamet wrote in her column, adding:

At times it has forced me to starve myself, to run extra miles, to abuse my body. As a teenager I used to stand in front of the refrigerator late at night staring into that white fluorescent light, debilitated by the war raging inside me: whether to give in to the pitted hunger in my stomach or close the door and go back to bed. I would stand there for hours, opening and closing the door, taking out a piece of food then putting it back in; taking it out, putting it in my mouth, and then spitting it into the garbage.

It was Mamet’s dad who led Mamet on the road to recovery. He was able to instill in her that the harm she was inflicting on her body didn’t just affect her, but those who loved her. And in treatment, Mamet discovered what her disorder was really about: control. “My disorder has never really been about weight or food — that's just the way the monster manifests itself. Really these diseases are about control: control of your life and of your body,” she wrote.

In speaking out about her disorder, in the same vein as singer Demi Lovato who has been open about her struggle with bulimia and self-harm, Mamet hopes to encourage others to do the same. As it stands, the National Association of Anorexia Nervosa and Associated Disorders (ANAD) reports only one in 10 men and women seeks treatment. That's far too little, considering the ANAD also reports eating disorders have the highest mortality rate of any mental illness.

"We all suffer in some small way; we are all a little bit ashamed of that second cupcake," Mamet wrote. "Let's diminish the stigma. Let's remind one another that we're beautiful."