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USA TODAY - Eating disorders can take several forms. The National Institute of Mental Health offers this summary of the symptoms. For details about the medical consequences of these disorders, visit www.nimh.nih.gov.

Anorexia nervosa is marked by an obsessive pursuit of thinness, the perception that one's body is "fatter" than it really is, a fear of gaining weight, extremely restricted eating and, as a result, emaciation.

Bulimia nervosa involves a pattern of binge eating, then purging by induced vomiting, fasting, abuse of laxatives or diuretics, and/or excessive exercise.

Binge eating differs from bulimia in that periods of eating large amounts of food is not followed by a purge, so binge eaters tend to be overweight or obese.

MORE: Eating disorders boom as kids enter college

Eating disorders not otherwise specified involve disordered eating habits that don't meet the criteria for anorexia or bulimia. This can be a combination of behaviors, says Holly Fitzhenry, a counselor at Mercy Ministries. For example, a student might have soda and chips as a meal, exercise for three hours, satisfy hunger pangs with a fast-food binge, then purge out of guilt. That's not the only pattern in this group, Fitzhenry emphasizes. Following a series of fad diets is another.

Eating disorders are only superficially about food, therapists say.

"The disorder is the external manifestation of what's going on inside," says Elizabeth Llewellyn, executive director at Eating Disorders Coalition of Tennessee. These disorders grow from depression, anxiety, feelings of inadequacy or an inability to cope with the competitive pressures of college or life in general, and a need to feel in control, she said.

Eating disorders can be triggered by stressful events such as a death or divorce in the family, a breakup or an abusive relationship.

College students seem especially vulnerable to eating disorders, probably because of on-campus pressure to succeed, to choose a career, to please parents and keep up with peers, Llewellyn says. In addition, constant exposure to social media can exacerbate young adults' desire to look good, she says.

Websites promoting anorexic behavior provide virtual templates for self-starvation. A friendly sorority weight-loss contest can push whole groups into disordered eating behaviors as they compete with each other.

"Initially (the eating disorder) gives a sense of control," Fitzhenry says. "The irony is it turns around and begins to control them."

Find out more about eating disorders here, http://www.nationaleatingdisorders.org/.

Madi O'Dell was treated successfully in Children's Hospital Colorado's Eating Disorders Unit (EDU) for bulimia, an eating disorder, which began her freshman year in high school.

In this series of videos, Madi candidly shares her teen perspective about her experience. She's also joined by her mom, Sue O'Dell, and high school counselor and coach, Mike Deutsch, who provide tips for adults who suspect a kid they know may be struggling with an eating disorder. Together, Madi, Sue and Mike hope to educate and inspire others about the dangers of eating disorders and the facts and resources available for those who seek treatment.

Read more about Madi's story here, http://bit.ly/W4YRTQ.

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