11/25/2013 11:41 am ET | Updated Jan 25, 2014

Anorexia: You Are Not the Person You Were (And the Holidays Only Make It Worse)

"I don't understand," a parent might say of a child who has anorexia. "She used to be the nicest kid." Or, "He used to be so considerate. What happened?"

There are many physical changes when it comes to anorexia -- the symptoms of starvation, the lack of body warmth, the insomnia, the brittle bones and chemical imbalances. These can be life-threatening. But the effect on the mind can be just as deadly and maybe even more insidious.

In James Lock's and Daniel le Grange's extraordinary book, Help Your Teenager Beat an Eating Disorder, they explain how having an eating disorder takes over a person in a way that is all-encompassing. They describe it like a Venn diagram -- or you could call it an eclipse. Imagine two circles, one plain, one shaded in. The kid, pre-anorexia, is the plain one, The shaded one is anorexia. Gradually, as the kid succumbs to the eating disorder, the shaded circle covers the plain one, until there's an almost total eclipse.

Once eclipsed, kids are changed in profound ways, and their personalities undergo complete transformations. It's devastating for parents to see their nice, hard working, smart children grow suspicious and manipulative, desperately twisting the truth with fierce determination.

This is because anorexia takes kids' good qualities and uses them destructively and ruthlessly. If a kid has been hardworking, he begins working hard to be the best anorexic he can be. If she is disciplined, she never lets herself slip or fail at being anorexic. If he is smart, he figures out the best lies to convince people he's not hungry (though he's famished); or has already eaten (as proof, there's an empty plate in the sink); or isn't cold (even though he's wearing a sweatshirt in August); or wasn't up all night (despite the dark circles beneath his eyes); or wasn't exercising in his room at 3 a.m. (that noise you heard was coming from next door).

If parents challenge any of these lies, they are told: "You don't trust me." "You are violating my privacy." "You think I'm a baby who needs constant watching." The lies often intensify around the holidays, with its emphasis on families eating big meals together. Anorexic kids frequently insist on eating separately, so the small amounts of food they eat or don't eat will go unnoticed. This is an unlikely option at Thanksgiving dinner.

Anorexia changes inner perceptions, too, the very things kids are seeing, hearing, feeling. To everyone but the girl with anorexia, she looks sickeningly gaunt. But, as a victim of body-image distortion, she looks in the mirror and sees a fat girl. Boys exercise like crazy, and when they look at their reflections, instead of seeing their chests caving in, they see a powerful six-pack.

They don't hear or understand what you're saying. Instead they hear accusations and cruel thoughts. "Please eat something," a parent might say. You want to make me fat, the kid hears. "You need to be healthy." You want me to be a loser.

When I was doing research for a young-adult novel about male anorexia, one young man told me that, back when he was dangerously anorexic, he took great pride in feeling the way his chest was bulking up even though his hands had to pass over his ribs, which stuck out prominently. His hands, he said, simply wouldn't "notice."

If kids with anorexia seem different, it's because they are. Pre-eclipse, they're good sons, good daughters, good brothers, good sisters, good friends. Post-eclipse, they're good anorexics.

If you're struggling with an eating disorder, call the National Eating Disorder hotline at 1-800-931-2237.

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