Eating disorders during weight loss: Clinical identification and intervention of anorexia nervosa and bulimia nervosa

I. Overview Eating disorders (ED) refer to unhealthy eating habits caused by psychological problems, which may eventually become life-threatening health risks. ED is common among people with biases regarding diet and nutrition, especially those who are overly strict in controlling their body shape or even addicted, and the causes are complex. Survey data shows that more than half of female college students have experienced extreme dieting, of which 40% have used drugs or meal replacements to lose weight, and nearly 20% of this group are underweight (BMI < 18.5 kg/m²). According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) of the American Psychological Association, ED is divided into three categories: 1. Anorexia nervosa (AN): Based on different eating behaviors, AN is divided into restrictive and bulimia/purging types. Patients can switch between these two subtypes, and data shows that 50% to 64% of AN patients also have bulimia nervosa and purging behaviors. 2. Bulimia nervosa (BN). 3. Other Eating Disorders (EDNOS): These include bulimia nervosa (BE), anorexia nervosa or bulimia that does not fully meet the DSM-V diagnostic criteria (e.g., weight <15% of ideal body weight, menstrual irregularities), and extreme dieting methods. The difference between BE and BE/BN is that BE patients will induce vomiting or abuse laxatives to "eliminate ingested calories" after binge eating. II. Causes and Diagnosis: Anorexia nervosa (AN) typically occurs between adolescence and age 40, often caused by a traumatic event or stress. Long-term energy restriction and weight loss in AN patients can lead to various malnutrition and physical complications, including amenorrhea, estrogen deficiency, osteoporosis, abnormal thermoregulation, anemia, and cardiac dysfunction, which can be life-threatening in severe cases. Furthermore, AN patients often experience psychological disorders such as depression, anxiety, social phobia, obsessive-compulsive disorder (OCD), and substance abuse. AN is among the mental illnesses with the highest mortality rate; besides fatal complications, a large number of deaths are due to suicide. The diagnostic criteria for anorexia nervosa (AN) in DSM-V include: A. Significantly low body weight due to restricted energy intake (mild: BMI ≥ 17 kg/m²; severe: BMI < 15 kg/m²); B. Fear of obesity or weight gain; C. Body image disorder and negative perceptions of one's own weight and body shape. When B and C are met but the weight is normal, it is considered atypical anorexia nervosa and should be diagnosed as EDNOS and treated accordingly. III. Management of Anorexia Nervosa

Treatment principles: restore healthy weight and bodily functions (menstruation, libido, ovulation); treat complications in a targeted manner; encourage patients to cooperate with treatment and rebuild a healthy eating mindset; repeatedly assess their psychological state; help establish family support; and prevent recurrence of the condition.

Phased nutritional reconstruction: For individuals with severe illness, significant low weight, and requiring hospitalization: (1) Stabilization phase: Correct electrolyte imbalance and dehydration, stabilize vital signs, and ensure intake of 55%-75% of required calories. Generally lasts 24 weeks. Pay attention to preventing refeeding syndrome. (2) Recovery phase: Increase calorie intake to achieve weight gain and achieve positive energy balance. It is recommended to plan for a weight gain of 0.25-0.5 kg per week (outpatient) or about 1 kg per week (hospitalization). (3) Consolidation and maintenance phase: After reaching the target weight, help the patient learn to eat independently, regulate their diet, and monitor their condition.

Nutritional intervention: Helping patients adjust their energy intake and output balance. Due to factors such as anxiety and gastrointestinal problems, patients with anorexia often have increased resting energy expenditure, frequently requiring an additional 200-400 kcal of energy to maintain their weight. The recommended macronutrient intake ratio is: carbohydrates 50%-55% or 45g/kg ideal body weight; fat 25%-30%; protein 15%-20% or 0.8-1.2g/kg ideal body weight. Other recommendations include avoiding caffeinated beverages, avoiding carbonated drinks (carbonation increases satiety), gradually reintroducing previously "absent" foods, and ensuring adequate fluid intake.

Psychological intervention is the most crucial aspect of treating ankylosing spondylitis (AN). It includes one-on-one therapy, family therapy, and group therapy. The psychotherapy process is generally lengthy, and full recovery may take several years.

Drug treatment: Drug treatment is generally not recommended unless the above interventions are ineffective or it is an adjunct treatment for complications.