Anorexia nervosa may surface any time between the ages of 6 and 30, but it usually begins during the teen years. Anorexia nervosa often begins when a teenager successfully follows a diet or when a teen decides to "buff up." Many times the teenager is at a normal weight when they begin to diet. The teen reaches the chosen goal, but feels they are still not thin enough. Even though the individual may now be extremely thin, they feel fat. So the teen resolves to diet even more. Anorexia nervosa affects girls more often boys, but there has been an increase in the number of males suffering from anorexia. Guys face similar societal pressures to be strong/buff and also have trouble with self-esteem issues that contribute to the development of eating disorders.

The person's family may not realize what's happening until the anorexic becomes dangerously underweight. By this time, they may not be eating anything at all or may still be eating some food, while severely restricting their fat intake. Exercise may continue relentlessly, for hours each day, adhering to a rigorous schedule that burns up even more unwanted calories.

No matter what the person's friends and family might say, the anorexic refuses to give up their extreme diet. Without professional intervention, the individual will continue to get thinner until their health, or life, is in serious danger.

Anorexia usually begins in the teen years. The typical anorexic is a perfectionist and an overachiever, excelling in school and involved with lots of activities.

Often, the preoccupation with weight starts in response to a stressful event, like changes with or loss of friends or problems in the family. Or, it may begin as a way to stave off general pressures like growing up, "fitting in" socially, doing well in school, or keeping things happy in the family. Such preoccupation represents an attempt to regain control over a sometimes painful, confusing world. But then the diet begins to control the dieter.