Amenorrhea is a symptom of anorexia nervosa.

The most distinguishing feature of anorexia nervosa is a perception that despite being at a healthy weight for under weight, patients still see the need to lose more weight or still feel dissatisfied with their weight and shape.

Note: Jane's perception of her previously healthy weight as “really overweight” and the discomfort on discussing her weight and weight loss.

Note: Jane's body language shows evident discomfort and reluctance for being weighed. Patients with anorexia nervosa can be embarrassed about their weight, and try to avoid others knowing about their weight, weight loss or weight gain.

Note: Jane's has a negative reaction to seeing her weight. Patients will often show disappointment, frustration, or embarrassment and perceive their weight is not low enough. Patients with anorexia nervosa often weight themselves at home, sometimes obsessively, and can worry excessively over the consistency of different scales.

Differential diagnosis of weight loss

Non-intentional:

• Endocrinopathies
  • Hyperthyroidism
  • Diabetes malitus
• Gastrointestinal diseases
• Malignancy
• HIV and other infections
• Advanced cardiac, pulmonary or renal disease
• Neurological diseases*
• Systemic inflammatory disorders
• Psychiatric disorders
• Drugs
  • Over the counter
  • Prescription drugs
  • Substance abuse

Common inappropriate responses and misconceptions to a patient's weight loss if it appears indicative of an eating disorder:

1. Praise or positive feedback on the weight loss, such as “Good for you for getting healthier, you look great!” This can motivate the patient to continue more weight loss.
2. The thought that her weight is not really that low, or low enough for anorexia nervosa without further questions or information. Many patients engage in eating disorder behaviours and exhibit symptoms before their weight is clinically considered underweight. Early intervention and treatment improves chances of recovery.
3. The thought that maybe she's just lost her appetite because she's just depressed — you should follow up on the weight loss with more questions before dismissing the possibility of an eating disorder.

BMI side bar:

Recap: The most distinguishing feature of AN is a perception that despite being a at a healthy weight or under weight, patients still see the need to lose more weight or still feel dissatisfied with their weight and shape.