Guide to Eating Disorders: Causes, Symptoms and Treatments

Anna Fenton
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Last Updated:

7 min read

Healthy Matters

Eating disorders are an increasing mental health issue in Hong Kong, particularly prevalent amongst teenage females, as statistics reveal. People of all genders and age can be affected. If untreated, disordered eating can damage the physical, mental and emotional health of patients.


What are eating disorders?

Eating disorders are defined by the American Psychological Association as abnormal eating habits that threaten health or even endanger the lives of patients. As a result of disordered eating patterns and distorted attitudes towards body weight and body image, sufferers can harm both their physical and psychological health. Among others, the two most serious types of eating disorders are anorexia nervosa and bulimia nervosa.


Anorexia nervosa

Anorexia nervosa is characterized by extreme weight loss, distorted body image, plus irrational fears of gaining weight and becoming obese. It is a common eating disorder, especially, but not exclusively, amongst adolescents. According to National Collaborating Centre for Mental Health, subtypes of anorexia nervosa are:

  • Restricting type: the weight loss is caused by limiting food intake and the person has not regularly engaged in binge-eating or purging behavior.
  • Binge-eating/purging type: the person regularly engages in binge-eating often followed by purging, to manage weight.


Bulimia nervosa

Bulimia nervosa is characterized by repeated bouts of excessive eating, followed by self-induced vomiting, taking laxatives or diuretics, fasting or vigorous exercise. Symptoms of bulimia nervosa are similar to the binge-eating/purging subtype of anorexia nervosa, with the difference being that bulimia nervosa patients can often maintain a normal weight. However, this makes bulimia nervosa more difficult to diagnose. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM), subtypes of bulimia nervosa include:

  • Purging type: the person engages in self-induced vomiting or the misuse of laxatives regularly.
  • Non-purging type: the person opts for other inappropriate compensatory behaviors, such as fasting or excessive exercise, but has not engaged in self-induced vomiting or misuse laxatives, diuretics or enemas regularly.

What are the causes of eating disorders?

These are complex and not yet fully understood, but scientists believe eating disorders are caused by biological, cognitive and social factors. 


Biological causes of eating disorders

  • Low serotonin levels: Serotonin is a hormone responsible for stabilizing mood, feelings of well-being, satisfaction, status and happiness. Past research suggested that eating disorder patients generally have lower serotonin levels than individuals with regular eating habits normal serotonin levels. Since research suggests that serotonin is responsible for promoting self-control, satiety, regulation of hunger and physiological homeostasis and regulation of caloric intake, low serotonin levels may increase the chance of developing eating disorders. Most of our serotonin comes from our food, so logically if we restrict food intake, we limit our serotonin levels as well.
  • Genetic factors: Individuals can be genetically predisposed to eating disorders. As such, females with a family history of eating disorders are more likely to develop eating disorders. Other research further suggests that eating disorders are linked to genes on chromosome 1. Eating disorders can also be a “learned behavior.” It’s not unusual for two sisters in one family or a mother and daughter to be affected

Cognitive causes of eating disorders

  • Distorted perception: Eating disorder patients may possess distorted perceptions about dieting. For instance, eating disorder patients may carry faulty assumptions such as “eating food is harmful” and “eating will make me fat”, causing them to check on their body shape frequently.
  • Negative body image: Patients with eating disorders are usually dissatisfied with their body shape. This body dysmorphia creates negative self-image and frequently leads to eating disorders.

Sociocultural causes of eating disorders

  • Parenting and Family: Research argues that children raised by less than nurturing or dysfunctional parents often struggle to develop inner self-resilience and positive self-esteem. In adolescence, these youngsters are often overly sensitive to comments about their body and develop a negative self-image. They can become overly reliant on validation from others about their appearance, especially about weight, making them susceptible to trying to alter their body shape by restricting or purging. Eating disorders often have their origins in dysfunctional family systems, so it is important to consider the family dynamics in every case. A mother obsessed with dieting and being thin can transmit these unhealthy negative obsessions to her daughter. Unthinking comments by a father or brother to a teenage girl about her body size can trigger shame and dramatic changes in eating habits in response.
  • Media influence: Television, social media and advertisements often portray thinness as beautiful and physically attractive. This message may cultivate a mindset perceiving a thin body as the only form of beauty. Their resulting fear of gaining weight can lead to restricting food and become an eating disorder. 

What are the physical symptoms of eating disorders?

Physical symptoms of anorexia nervosa

In addition to dramatic weight loss, patients with anorexia nervosa may experience:

  • Headaches, fainting and dizziness
  • Dry skin and lips, brittle nails, thin hair, easy bruising, yellow complexion, growth of thin white hair over body (lanugo) and intolerance to cold
  • Poor circulation, irregular or slow heartbeat, hypotension, cardiac arrest and heart failure
  • Anemia (low iron levels in blood)
  • Constipation, diarrhea, bloating and abdominal pain
  • Irregular or absent periods, loss of libido and infertility
  • Dehydration
  • Kidney failure
  • Loss of bone calcium (osteopenia) and osteoporosis
  • Muscle loss, weakness and fatigue
  • In postmenarcheal females, amenorrhoea, i.e. the absence of at least three consecutive menstrual cycles or if periods occur only after hormones intake, e.g. estrogen administration

Even after recovery, patients may still suffer from complications in the long-term, for example, difficulty in childbearing.


Physical symptoms of bulimia nervosa

According to the US National Institute of Mental Health, the physical symptoms of bulimia nervosa include: 

  • Tooth abrasion and/or decay
  • Acid reflux
  • Constipation
  • Stomachache
  • Electrolyte imbalance e.g. sodium, potassium and calcium
  • Irregular heart rhythm
  • Atrial fibrillation
  • Heart failure
  • Hormonal disturbances
  • Other serious complications

What are the psychological symptoms of eating disorders?

Psychological symptoms of anorexia nervosa

Aside from physical symptoms, patients with anorexia nervosa also experience profound psychological symptoms.


In general, psychological symptoms of eating disorders concern thought patterns and feelings. Common psychological symptoms include:

  • Intense fear of weight gain
  • Refusal to maintain body weight
  • Extreme mood swings
  • Signs of anxiety
  • Signs of depression
  • Preoccupation with food and calories
  • Frequent critical checking in the mirror
  • Discomfort while eating
  • Cutting up food into smaller pieces
  • Withdrawal from social activities

Psychological symptoms fo bulimia nervosa

The psychological symptoms of bulimia nervosa are similar to those of anorexia nervosa. In essence, common behavioral symptoms of bulimia nervosa include:

  • Binge eating
  • Self-induced vomiting
  • Fasting
  • Excessive exercising

Diagnosis of eating disorders

Mental health professionals usually employ the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to diagnose patients susceptible to eating disorders.


On the authority of the DSM-criteria for eating disorders, individuals who show the following symptoms over the last three months may have eating disorders:

  • Restriction of food, significant weight loss considering age, sex and physical health. 
  • Intense fear of gaining weight or becoming fat.
  • Low self-worth influenced by body weight or shape, or body dysmorphia, the refusal to acknowledge dangerously low body weight.

In addition to DSM-5, mental health professionals rely on psychological self-assessment questionnaires for diagnosis. They can also use clinical rating scales, including:

What are the treatment options for eating disorders?

Treatment options for eating disorders include:

  • Treatment of medical symptoms
  • Attempts to restore healthy body weight
  • Nutrition education and counseling
  • Individualized psychotherapy
  • Family therapy
  • Group therapy

Treatment examples:


The Maudsley method: family-based therapy

The Maudsley Method provides guidelines to help adolescents and children with eating disorders by supporting parents to take a central role in diet management. Parents temporarily take control of the patient’s food and activity, e.g. selecting, preparing, serving and supervising meals and snacks, until the patient shows evidence of weight gain. When the adolescent is at or near full weight restoration and self-starvation behaviors have subsided, the treatment may conclude with further support.


Cognitive-behavioral therapy

Cognitive-behavioral therapy (CBT) targets in-patients and out-patients, aiming to change negative self-statements and basic assumptions anorexic patients maintain. Mental health professionals first identify patients’ cognitive biases, then replace their irrational thoughts with logical ones.


Behavioral treatments

These target in-patients with more severe conditions. This approach focuses on helping the patient to recover from anorexia by changing their behavior. For example, mental health professionals may teach anorexic patients to formulate new eating habits with a goal toy, increase their amount of food consumption.

Can eating disorders be prevented?



Prevention interventions of eating disorders may be implemented under clinical, community and school-based settings. Programs that focus on changing the weight-related attitudes of youth and promoting healthy weight-control strategies aim to prevent eating disorders.


Develop new interests

One solution to prevent developing eating disorders is to distract yourself from paying too much attention to your weight. It helps to break the habit of checking your body shape and frequently weighing yourself. Consider developing an interest in outdoor activities like hiking and swimming to shift attention away from your physical appearance.


Practice self-love, self-esteem and self-worth

Eating disorder sufferers almost always have low self-worth and negative beliefs that lead to chronic low self-esteem. They often have “other esteem” which means they rely on other people to provide their feelings of value and worth. Until they reduce their reliance on the fickle opinion of others and learn the skill of esteeming themselves from within, recovery can be difficult.  Eating disorders can also result from early negative childhood experiences such as loss of a parent or beloved relative, abuse and even sexual abuse, so an assessment by a qualified and experienced clinician is advised to get an accurate diagnosis of the underlying cause. There is often a strong addictive element at work with bulimia nervosa as the act of vomiting is a powerful stress reliever and creates an endorphin response. Endorphins are the body’s natural opiates and in this way vomiting after bingeing becomes a compulsive habit with a payoff. Anorexia nervosa causes starvation and one of the body’s ways of enduring the pain of starvation during times of famine was to induce a sense of euphoria, a natural high. This “high” has been a feature of fasting for religious purposes throughout history. Thus self-induced starvation can also become highly addictive, with anorexics being able to go without food for long periods thanks to this natural payoff.


Therefore it may be helpful to see the complex topic of eating disorders through the lens of an addiction while considering which of the many treatment approaches will work best.

Further support

In case you need immediate support, please reach out to mental health professionals. Below is a list of organizations that offer eating disorders counseling:

Hong Kong Eating Disorder Association Limited 
Address: Unit 101, 1/F, The Mills, 45 Pak Tin Par Street, Tsuen Wan
Tel: 2850 4448
Email: [email protected]


The Lighthouse Counseling
Address: 15/F, Bonham Centre, 79-85 Bonham Strand, Sheung Wan, Hong Kong
Tel: 6086 7995
Email: [email protected]


Address: Suite 1202, Chinachem Hollywood Centre 1 Hollywood Road, Central, Hong Kong
Tel: 2521 4668
Email: [email protected]


Child Development Team
Address: 10th Floor, One Island South, Suite 1015, 2 Heung Yip Road, Hong Kong
Tel: 2592 9000
Email: [email protected]


ReSource The Counselling Centre Limited 
Address: 701, China Hong Kong Tower, 8-12 Hennessy Road, Wan Chai, Hong Kong
Tel: 2523 8979
Email: [email protected]


What is an eating disorder?

Eating disorders are characterized by abnormal eating patterns causing physical, mental and emotional distress, typically accompanied by body dysmoephia, a distorted body image. The primary constituent of eating disorders is under or over eating, with or without compulsive bingeing and purging patterns.

Can you have an eating disorder and not realise?
Who is most likely to get an eating disorder?
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This article was independently written by Healthy Matters and is not sponsored. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.

Anna Fenton
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