Eric Charbonneau/Invision for Twentieth Century FOX/AP
says she's suffered from an eating disorder for most of her life – in secret.
The actress opened up about her battle in her column for the September issue of Glamour
"This struggle has been mostly a private one, a war nobody knew was raging inside me," she writes. "I tried to fight it alone for a long time. And I nearly died."
The 26-year-old says her struggle started at the age of 8 when she was told she was fat for the first time.
"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."
In her column, the Girls star
also says that pressure from society played a part in her disorder.
"Our culture delivers a real one-two punch: You want to control something, and then society says, 'Hey, how about controlling the way you look? Skinny is beautiful,' " she says.
"It's no secret that we live in a country with a warped view of beauty."
She eventually sought treatment after her father, playwright David Mamet, intervened, but her recovery wasn't immediately smooth sailing. After Mamet left the hospital, she quickly lost the weight she had gained in treatment.
But today, the actress is at a healthy weight and considers herself "an addict in recovery … I realize that my obsession will always be with me." She is also encouraging others to speak openly about eating disorders.
"Let's diminish the stigma," she writes. "Let's remind one another that we're beautiful."