Anorexia Nervosa and Bulimia Nervosa - Nutritional Disorders

ANOREXIA NERVOSA AND BULIMIA NERVOSA

Anorexia nervosa (AN) and bulimia nervosa (BN) are both disorders of eating behavior and body weight regulation. Anorexia is simply a lack of appetite; bulimia is derived, in part, from the Greek word limos meaning hunger. Both have received considerable publicity in recent years although they were reported many centuries ago. The prevalence rate for AN in young females is estimated to be 0.3% and for BN 1% and 0.1% in young women and young men respectively. The incidence in the general population is much lower with the incidences of AN and BN being approximately 8 and 12 cases per 100 000 respectively.

Anorexia nervosa is an extreme refusal or reluctance to eat and associated psychological problems, leading to a severe weight loss. Compulsive exercising and the abuse of laxatives and diuretics often compound the reduced input of dietary energy. Patients are therefore normally extremely hungry and are obsessed with food but they avoid eating, especially carbohydrates. The signs and symptoms of AN include a body weight at least 15% below the recommended weight, a ‘wasted’ appearance with reduced muscle mass, and swelling of the joints. In younger females, puberty is delayed; an older female is likely to become amenorrhetic and infertile because her body weight reduces to less than 45 kg and/or fat content becomes less than 22% of body weight. The skin is dry, hair thin and the nails brittle. Constipation and decreased heart rate and blood pressure are common. If left untreated, long-term damage to the skeleton and cardiac systems are likely and death can result from starvation, cardiac arrest or other complications. Sufferers of AN are often of above average intelligence but generally have a grossly dysmorphic view of their own bodies, seeing themselves as obese, even though they ‘know’ they are underweight. It is unclear as to what causes this view. It has been suggested that overreactions to relatively mild obesity, peer or social pressures regarding an ideal human shape or a wish to delay the onset of menarche may all be linked to the condition.

Bulimia nervosa is characterized by episodes of excessive or ‘binge’ eating that induce feelings of guilt such that sufferers induce vomiting to void the food. This cycle of eating and induced vomiting can be repeated many times. As with anorexics, the use of laxatives, diuretics and dieting pills may be abused. The condition tends to affect older patients than those with anorexia. The signs and symptoms of BN include puffy cheeks due to enlarged salivary glands and often severely damaged tooth enamel because of the excessive vomiting. Electrolyte imbalance, such as loss of potassium, can cause health problems and increases the risk of cardiac arrest. However, patients generally manage to maintain their weight at an appropriate value and so the condition may not be noticed and can remain undetected for many years.