According to Western epidemiological studies, the prevalence of anorexia is about 0.5%~1.5%. More common in teenagers and young women. Although the incidence of this disease is low, the mortality rate is high (5%-15%).

The prevalence of this disease varies around the world, with the highest prevalence reported in Western countries such as Europe and the United States.

The peak ages of onset of anorexia nervosa are 13 to 14 years old and 17 to 19 years old. Female patients outnumber males by about 10:1.

Patients often engage in excessive dieting, fasting, or excessive exercise to control or lose weight.

Patients have combined binge eating and/or purging behaviors, Weight loss is achieved through actions such as self-induced vomiting, laxatives, diuretics, or enemas.

Genetic factors: Through investigation of family history of anorexia, it was found that The prevalence of the disease in families with anorexia nervosa is significantly higher than that in the general population, about 50%-80%.

Personality characteristics: Patients with anorexia nervosa often have personality traits of perfectionism, self-doubt, and harm avoidance. Such traits interact with developmental stage, life events, and environment to become one of the susceptibility factors to anorexia.

Individual psychological factors: confusion and lack of acceptance of pubertal development.

Social and cultural factors: The ideal body shape is influenced by social and cultural factors. There is no doubt that the influence of the media and fashion industry on modern people. Especially in certain occupations such as dancers, fashion models and other occupations, the prevalence rate is 3-4 times that of the general population.

Family factors: Some studies have found that families of anorexic patients are often characterized by conflict avoidance, overprotection, tangled parent-child relationships, and unclear boundaries. But more research has found that the occurrence of anorexia brings about the above-mentioned changes in families. Therefore, family factors are regarded more as maintenance factors of the disease.

Life events: Research shows that adverse life events are risk factors for mental disorders and are closely linked to anorexia.

Mainly the fear and anxiety about weight gain and the special "pleasure" about weight loss, Distorted experience of body weight and shape (thinking that one is “okay” or still “fat” despite being very thin).

The main manifestation is extreme weight loss, often accompanied by a series of symptoms such as malnutrition, metabolism, endocrine disorders and sleep disorders. Patients lose weight within a few months after the onset of the disease, often below 15% of the standard body weight.

Mainly manifested by restricting or refusing to eat, being picky about food, and avoiding eating-related situations. As well as behaviors that actively interfere with weight such as excessive exercise, inducing vomiting, catharsis, diuresis, and taking appetite suppressants. Behavioral withdrawal and reduced interpersonal interactions are often secondary behavioral characteristics of anorexia.

Such as anxiety, depression, obsessive-compulsive disorder, emotional instability, irritability, insomnia, etc. Usually as the disease progresses and the weight loss becomes more severe, the above problems become more prominent.

The patient's neuroendocrine system also undergoes corresponding changes.

Patients often complain of abdominal pain, bloating, early satiety, constipation caused by slowed gastrointestinal emptying, and diarrhea caused by the use of laxatives. At the same time, patients suffer from malnutrition and hypometabolism due to low nutritional intake. Due to severe malnutrition, patients often develop edema of the limbs.

Amenorrhea occurs in almost 100% of female patients. At the same time, it will also be accompanied by decreased sexual function, loss of pubic and armpit hair, and atrophy of the breasts and uterus. Decreased gonadotropin release results in hypogonadism. It is more common in male patients. Pre-adolescents have delayed sexual, psychological and physical development.

50% of women with anorexia nervosa have bone density measurements that are more than 2 times lower than normal. Patients may develop symptomatic compression fractures and kyphosis, Bone loss generally occurs 6 months after the disease begins.

In addition, patients may also have other neurotic symptoms.

①Avoid “foods that cause weight gain”;

②Self-induced vomiting;

③ Self-induced defecation;

④Excessive exercise;

⑤ Taking anorexia agents or diuretics;

①Avoid “foods that cause weight gain”;

②Self-induced vomiting;

③ Self-induced defecation;

④Excessive exercise;

⑤ Taking anorexia agents or diuretics;

That is, routine physical examination items, such as height, weight, laboratory tests, etc., are used to evaluate the level and changes of patients' malnutrition.

Routine blood/biochemical tests will show whether the patient has anemia, leukopenia, Suppression of bone marrow hematopoietic function, hypoalbuminemia, liver and kidney function damage, cardiac enzyme changes, hypokalemia, etc.

Endocrine hormone level and function tests to verify the function of the hypothalamic neuro-pituitary axis and the presence or absence of primary dysfunction of each target gland in amenorrhea patients with anorexia nervosa.

Self-monitoring: Record daily caloric levels, nutritional intake, exercise, Number of binges and purges, types of food eaten, when and where food was eaten, and emotional state information.

Self-report scales: including eating attitude test and eating disorder questionnaire.

Electrocardiogram examination: In order to promptly detect whether the patient has arrhythmia caused by severe malnutrition or water and electrolyte imbalance.

X-ray examination: In order to promptly detect whether the patient has severe osteoporosis and kidney stones caused by excessive dieting, Chest radiography can detect tuberculosis infection in some severely malnourished patients.

Electroencephalogram examination: Due to unbalanced nutritional intake and long-term hunger in patients with anorexia nervosa, It can lead to a decrease in specific amino acids in the blood. Long-term deficiency may cause epileptic seizures in patients and abnormal electroencephalograms.

Imaging examination: such as head CT and MRI examination to identify the hypothalamus, pituitary gland and other parts of the body Whether space-occupying lesions occur, excluding anorexia and endocrine disorders caused by brain tumors.

There is no severe malnutrition, but there is hypofunction of the thyroid gland and adrenal cortex. Loss of armpit hair and pubic hair, history of heavy childbirth bleeding, postpartum agalactia, and amenorrhea.

Such as atrophic gastritis, chronic pancreatitis, etc.

Especially the loss of appetite caused by digestive tract tumors, such as esophageal cancer, gastric cancer, etc. Rapid weight loss is often accompanied by symptoms such as gastrointestinal bleeding and abdominal mass.

Manifested as male sexual desire loss, depression, sleep disorders, decreased bone density, etc. Symptoms are similar to those of anorexia nervosa, but symptoms such as central obesity and increased visceral fat are often present. Detection of free testosterone and reproductive endocrine hormones in blood can be used for differential diagnosis.

Such as food refusal caused by schizophrenia, depression or obsessive-compulsive disorder, Decreased appetite, reduced eating, etc., resulting in weight loss and malnutrition.

BMI<14; blood pressure <80/50mmHg; heart rate <40 beats/min; weight loss more than 1kg per week; Assistance is required when sitting up or squatting down from a lying position. The presence of one of the above conditions is a high risk.

Weight loss of more than 15% in the past 6 months; almost no food in the past 10 days; BMI <12; blood pressure <80/50mmHg; Heart rate <50 beats/min; serum potassium <2.5mmol/l; serum phosphorus <0.97mmol/l. The presence of one of the above conditions is a high risk.

The severity of a patient's eating disorder symptoms can be assessed with the Eating Disorder Examination Questionnaire, 6th Edition (EDEQ-6).

According to the severity of malnutrition of the patient Different levels of nutritional reconstruction programs are provided according to:

Closely monitor physical complications, monitor blood potassium and blood phosphorus concentrations in high-risk patients, and provide symptomatic potassium and phosphorus supplements in severe cases.

Closely monitor for the emergence of refeeding syndrome, usually by slowing down the rate of refeeding to prevent the risk of refeeding.

Psychotropic medication is needed when psychiatric symptoms that seriously interfere with treatment progress occur. Common medications include anxiolytics, Antidepressants, mood stabilizers and low-dose antipsychotics. Safety must be carefully considered when using medication.

Family intervention - family-based treatment (FBT) works best for adolescent patients.

Commonly used treatments for adults include cognitive behavioral therapy and focused psychodynamic therapy. The above psychological intervention methods all take weight restoration as one of the basic goals.