Eating disorders are what Dr. Phil calls a "silent epidemic." In the beginning, girls may choose to restrict their diets or to purge for one reason, but they end up continuing to do so because it becomes an addiction. Early intervention is crucial because once an eating disorder gets a grip on someone, it's far more difficult to treat.

There are warning signs that you do need to be looking for. "First off, you never see them eat. You'll see them push their food around the plate, but you'll see every kind of avoidance technique you can imagine because they regard food as poison," Dr. Phil explains. "If they're acting around food as though it's toxic or poisonous, that should be a clue for you."

Also, has your child been dressing in baggy clothes? "You're going to see really bulky sweaters and baggy pants to hide the weight loss and disguise the body," Dr. Phil says. "Look for extreme behaviors. Look for deception. Look for hiding."

Additional warning signs:

A significant change in apparent appetite

Excessive weight loss and an intense fear of weight gain

An unnatural preoccupation with food and calories

An obsession with clothing size, scales and mirrors

Routine secrecy, such as leaving the table immediately after eating to go behind closed doors

Avoidance of family meals or events at which food is present

Wearing bulky clothes to hide weight loss

Excessive exercise

Social withdrawal and moodiness