• Person refuses to maintain normal body weight for age and height.
• Weighs 85% or less than what is expected for age and height.
• In women, menstrual periods stop. In men levels of sex hormones fall.
• Young girls do not begin to menstruate at the appropriate age.
• Person denies the dangers of low weight.
• Is terrified of becoming fat.
• Is terrified of gaining weight even though s/he is markedly underweight.
• Reports feeling fat even when very thin.

In addition, anorexia nervosa often includes depression, irritability, withdrawal, and peculiar behaviors such as compulsive rituals, strange eating habits, and division of foods into "good/safe" and "bad/dangerous" categories.

Person may have low tolerance for change and new situations; may fear growing up and assuming adult responsibilities and an adult lifestyle. May be overly engaged with or dependent on parents or family.

Dieting may represent avoidance of, or ineffective attempts to cope with, the demands of a new life stage such as adolescence.