PICTURES: 12 Warning Signs of Anorexia She Doesn't Want You to Notice

(CBS) At a time when many Americans worry about being too fat, young women suffering from the eating disorder anorexia are dangerously thin.

Yet because anorexia gives these women a very distorted sense of their own body image, even they worry about being fat.

PICTURES: 12 Secret Signs of Anorexia

It's a cruel paradox - and an often deadly one. In fact, up to 10 percent of anorexics die within 10 years, making it the single most deadly mental illness, according to recent statistics.

The good news? Treatment can be life-saving - if it arrives in time. But that doesn't always happen, experts say, because women with anorexia often do such a good job of hiding their illness.

"Anorexia is very personal and is often hidden," says Marisa Sherry, RD, a New York City-based nutritionist who specializes in eating disorders. "If the subtler signs are missed the person may already be ingrained in their eating disorder and at high risk for medical complications," including electrolyte imbalances that sometimes result in heart attack.

Could someone you know and care about - perhaps even your own daughter - have anorexia? You already know to be on the lookout for extreme thinness. But there are other warning signs you should know about.

PICTURES: 12 Secret Signs of Anorexia