Anorexia nervosa

Anorexia nervosa (AN) is a psychiatric disease. Energy restriction, low body weight and an intense fear of gaining weight are characteristics of this disease. High emotional and financial burden make AN a devastating and costly disorder for patients and their families. AN can also be lengthy, physically destructive, and psychologically exhausting.

Diagnostic and Statistical Manual of Mental Disorders Book (DSM-IV) lists four criteria for the diagnosis of an AN

(1)  Refusal to maintain body weight at or above a minimally normal weight for age and height

(2)  Intense fear of gaining weight

(3)  Disturbance of one’s body weight or shape

(4)  Amenorrhea

The disorder ranks among the ten leading causes of disability among young women and has one of the highest mortality rates of any psychiatric disorder AN is recognized as the third most common chronic illness in adolescents and the teenage years are the most common time of onset of the disease. The lifetime prevalence of anorexia nervosa in women is 2.2%  but because only 50% of women with AN recover even many years after their initial diagnosis. This is a chronic disease for many women. In fact, the number of women over 35 years of age entering treatment facilities for anorexia nervosa has dramatically increased in recent years. Although primarily recognized in females, males are also affected by this disease. Although it is reported that 10% of individuals affected by AN are male, the incidence may be much higher.

One of the first observational studies in this field on fat avoidance reported  that individuals with AN consumed fewer calories than controls (1289 kcal vs. 2220 kcal) . This low calorie intake primarily caused by fat avoidance of the AN patients.  In that study, the macronutrient composition of caloric intake over a 24-h period was analyzed and it was found that individuals with AN  ate a slightly higher percentage of protein and carbohydrates than controls, but substantially less fat (17.6% vs. 28.4%).

Etiology of AN is unknown. There are determined various and generally nonspecific  psychological and biological risk factors of AN. However, this risk factors do not explain major fraction of the variance in occurance. Treatment for eating disorders in a structured environment usually restores normal weight in 2–4 months, in certain patients, with concomitant physiological, physical and psychological improvement. The fact that full recovery occurs in a substantial fraction of individuals who develop anorexia nervosa and that, despite numerous studies, no major physiological disturbances have been identified that are not reversed by weight gain suggest that cognitive and emotional factors play a major role in the development and persistence of AN.  Pre-meal psychological state may be one such factor by playing an important role in the food choices of individuals with AN. According to recent studies, pre-meal level of anxiety affects calorie intake negatively . Increased distress level might affect food choice function adversely.