When an individual presents with unexpected weight loss, the primary care physician determines whether it is related to an eating disorder and/or to another illness, such as diabetes mellitus, inflammatory bowel disease, celiac disease, a malignancy, thyroid dysfunction, or Addison's disease. Having an eating disorder does not preclude these other diagnoses.

Infectious mononucleosis, a virus that occurs most often in adolescents and young adults, can result in unintentional weight loss. When an individual recuperates from “mono,” her body—in its efforts to maintain homeostasis—will presumably return to its pre-illness weight range. Some post-mononucleosis patients, however, are particularly pleased with their weight loss—especially if they receive compliments for it—and aspire to get thinner, subsequently falling prey to an eating disorder.

The doctor will be interested in whether the individual has a history of depression, anxiety disorder, obsessive compulsive disorder or substance abuse. These conditions often coexist with eating disorders.

The primary care physician will want to know about the health of the individual’s family. Does she have relatives with a medical illness such as diabetes mellitus, colitis, cancer or thyroid disease? Are there family members with eating disorders, weight concerns, substance abuse, depression or other mental illness?

Another set of questions involves weight. What is the most and the least the patient has weighed and when did each of these occur? During this part of the interview, the physician not only collects facts but also explores the individual’s attitudes about her body size and shape. What would she like to weigh and how would achieving this goal improve her life? How frequently does she step on the scale? Is she trying to lose weight?

It is very important for an individual to be honest with her physician about her eating habits. One reason for this is that a person with an eating disorder may have a normal physical exam and normal laboratory tests, especially if she is in the early stage of the illness. And the severity of a patient’s eating behaviors is often key in determining whether treatment is indicated. What weight control practices has she engaged in? Has she cut back on the kinds and amounts of food she takes in? Does she eat large amounts within a short period of time? Does she take diet pills, diuretics, or laxatives? Does she induce vomiting? How long ago did she start these behaviors and how frequently has she engaged in them? When a patient has a particularly hard time telling her physician about her eating, information provided by the family can often help her get the care she needs.

Many individuals with eating disorders exercise to an extreme, often for the purpose of controlling their weight. The primary care physician is likely to ask the patient what sports or other physical activities (such as dance) she participates in. How frequent are her workouts and how long do they last? Does she train in solitude, feel compelled to exercise or find it difficult to stop? Has she had any sports injuries? Has she been tested for bone density?

Absent or irregular menstrual periods are a major feature of eating disorders. The doctor will want to know how old the patient was when her periods started. Have her cycles been regular or has she skipped some? Does she use birth control pills or other form of contraception? Has she been pregnant?

When asked about specific symptoms, some individuals say they feel fine while others report one or more of the following:

• Feeling cold
• Low in energy
• Irritable
• Low in mood
• Trouble concentrating or making decisions
• Constipated
• Frequent, persistent worries about food, body size or weight
• Heartburn
• Swollen cheeks
• Fainting
• Headaches
• Dizziness