Anorexia nervosa is an eating disorder. A person with anorexia nervosa feels compelled to control and lose weight and often finds that food dominates their life.
The weight loss may become severe and life-threatening. Treatment includes advice about eating, monitoring weight change, family therapy and talking treatments such as cognitive behavioural therapy (CBT).
What is anorexia nervosa?
Anorexia nervosa (often just called anorexia) is an eating disorder. It is ten times as common in women as in men. It most often starts during teenage years. About 9 in 1,000 women develop features of anorexia at some point in their lives.
People with anorexia often find that they do not allow themselves to feel full after eating. This means that they restrict the amount they eat and drink. People with anorexia are underweight. Sometimes, the weight becomes so low that it is dangerous to health.
Is anorexia dangerous? Can men have anorexia? Can anorexia give you diarrhoea? How do you help someone with an eating disorder? All your questions answered.
Deliberate weight loss
This is the main symptom. People with anorexia lose weight by avoiding potentially fattening foods or sometimes any foods. If you have anorexia, you limit the amount you eat and drink, in order to control how your body looks. You may often pretend to other people that you are eating far more than you actually are. You may be using other ways of staying thin such as exercising too much. You may also have made yourself be sick (vomit), take laxatives, or even take appetite suppressant medicines or 'water' tablets (diuretics).
If you are a teenager and still growing, you may not lose weight but you may not be gaining it as you should. The result will be the same, ie you are under the normal weight for your age and height.
People with anorexia typically weigh 15% (or more) below the expected weight for their age, sex and height. Your body mass index (BMI) is calculated by your weight (in kilograms) divided by the square of your height (in metres). For example, if you weigh 66 kg and are 1.7 m tall then your BMI would be 66/(1.7 x 1.7) = 22.8. A normal BMI for an adult is 18.5-25. Above that you are overweight and below that you are underweight. Adults with anorexia have a BMI below 17.5. If you are under 18 years of age, normal weight is assessed by using special age-related BMI charts.
With anorexia, you want to feel very in control of your body weight and shape. However, with time, anorexia can take control of you. After some time it can become very difficult to make healthy, normal choices about the amount and types of food you eat.
An unrealistic image of own body size
People with anorexia think that they are fat when they are actually very thin. Although other people see you as thin or underweight, it is very difficult for you to see this if you have anorexia. You are likely to have a severe dread (like a phobia) of gaining weight. People with anorexia will do their utmost to avoid putting on weight.
Studies show that if you are anorexic, what you see when you look at yourself in the mirror is different to what other people see. If you were asked to draw, or match a computer image of what you think you look like, you may think you are bigger than you really are.
Other features with anorexia
It is common for people with anorexia to:
- Vomit secretly after eating.
- Try hard to hide their thinness - for example, by wearing baggy clothes, or putting heavy objects in their pockets when being weighed.
- Conceal how much they eat.
- Like food and feel hungry. However, it is the consequences of eating that frightens them.
People with anorexia may also become obsessed with what other people are eating.
People with anorexia often restrict themselves to certain types of food. Eating food may even become like a ritual. For example, each time you eat, you have to cut your food into very small pieces. You may think frequently about your weight and even weigh yourself most days or even several times a day.
Physical symptoms caused by low body weight or poor diet
These are many, but can include:
- Dizziness or fainting.
- Feeling cold a lot of the time.
- Irregular sleeping patterns.
- Poor concentration.
- Others detailed in the 'health risks' section below.
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Anorexia nervosa health risks
Do not let the voice of anorexia in your head convince you that you are losing weight to be healthy. Being underweight is extremely unhealthy and can damage your health and even lead to death. Health risks are caused by under-eating (starvation) and by the methods used to get rid of eaten food - being sick (vomiting), excess laxatives, etc. You literally starve your body organs (such as your muscles, brain and heart) of the energy they need to function. Problems that may occur include the following:
Many women with anorexia have irregular periods, as hormone levels can be affected by poor diet. Their periods may even stop altogether or they may find that their periods have never started, especially if they started having eating problems when they were younger. Some women with anorexia may be unable to have a baby (be infertile).
Chemical imbalances in the body
These are caused either by repeated vomiting or by excess use of laxatives. For example, a low potassium level which may cause tiredness, weakness, abnormal heart rhythms, kidney damage and convulsions. Low calcium levels can lead to muscle spasms (tetany). Anorexia can also cause low sugar levels.
'Thinning' of the bones (osteoporosis)
Osteoporosis is caused by a lack of calcium and vitamin D and can lead to easily fractured bones. In addition, the risk of getting osteoporosis increases if you are a woman and your periods have stopped. This is because oestrogen in your body protects your bones from osteoporosis and the levels of oestrogen in your body reduce when your periods stop.
Problems with guts are common for people with anorexia. You may feel full after eating, bloated or sick (nauseated). You may have indigestion and/or tummy (abdominal) pains. Constipation is common as you are not eating or drinking enough for your guts to work properly.
You can also run into trouble if you take a lot of laxatives. Laxatives can damage the bowel muscle and nerve endings. This may eventually result in permanent constipation and also sometimes abdominal pains.
Swelling of hands, feet and face
This is usually due to fluid disturbances in the body.
These can be caused by the acid from the stomach rotting away the enamel with repeated vomiting.
Having a diet low in iron can lead to anaemia. This can make you feel weaker and more tired than normal. Dizzy spells and feeling faint can also occur.
It is common to feel low when you have anorexia. Some people develop clinical depression, which can respond well to treatment. It is important to talk with your doctor about any symptoms of depression you may have. Many people find they become more moody or irritable.
Anorexia can cause problems with the heart and circulation. Problems include leaking heart valves, low blood pressure, low heart rate and abnormal heart rhythms.
If you have anorexia, your body's defence system does not work as well and you are more likely to develop infections.
Hair and skin problems
You may find you have downy hair on your body and also the hair on your head becomes thinner. Many people with anorexia also have dry, rough skin.
What is the cause of anorexia nervosa?
The exact cause is not fully understood. Part of the cause is a fear of getting fat but it is not just as simple as that. Different causes possibly work together to bring on the condition. These may include the following:
Pressure from society
Pressure from the media and society to be thin is thought to play a part. This is probably why anorexia is much more common in westernised countries.
Personality and family environment
This probably plays a role too. People with anorexia often have poor self-esteem (not much self-confidence) and commonly feel that they have to be perfectionists. Often there are disturbed family relationships. All sorts of emotions, feelings and attitudes may contribute to causing anorexia. Traumatic events such as sexual abuse may make anorexia more likely, as do some dieting experiences.
Some studies of families with identical twins showed that if one twin has anorexia then the other has a 1 in 2 chance of getting it. However, not all studies have the same finding, so it is not known to what extent genetic factors are involved.
Brain changes have been found in people with anorexia. It is not known if these are the result of starvation, or if they are involved in the cause.
Are any tests needed?
Although there is no test to diagnose anorexia, your doctor may wish to do some tests. These may include blood tests to check for complications of anorexia - for example, anaemia, low potassium levels, kidney or liver problems or a low blood sugar (glucose) level. A heart tracing (electrocardiogram, or ECG) may be advised to check for an irregular heart rhythm.
What is the treatment for anorexia nervosa?
The aim of treatment is to:
- Reduce risk of harm (and death) which can be caused by anorexia.
- Encourage weight gain and healthy eating.
- Reduce other related symptoms and problems.
- Help people become both physically and mentally stronger.
If anorexia is suspected, you should be referred to a specialist eating disorders team, although unfortunately services in some parts of the UK are limited. This is a specialised mental health team which may include psychiatrists, psychologists, nurses, dieticians and other professionals. Usually this will involve outpatient appointments. Occasionally if you have very severe anorexia or medical complications, you may be admitted to a specialised eating disorder unit, or a medical ward in hospital. Medication is not usually necessary in treating anorexia.
The sorts of treatments that may be offered include the following:
Help with eating
It is best to have regular meals. Even if you only eat small meals it is beneficial to the body to eat at least three times a day. You should try to be honest (with yourself and other people) about the amount of food you are actually eating. You should reduce the number of times you weigh yourself; try to weigh yourself only once a week.
Your eating disorders specialist may suggest you keep an eating diary to write down all the food you eat. They will weigh you at regular intervals, and so you will be able to see the relationship between what you eat and the effect on your weight. They will be able to advise you on how much to eat, what your healthy target weight should be and how to safely reach it and over what time period.
Anorexia Focused Family Therapy
If you are under 18, it is likely that your parent(s) or carer(s) will be closely involved in this process. In the early stages of therapy, they will have more control over your eating choices. As you start to recover and become able to make rational and healthy decisions, more independence and control over what you eat is handed back to you. Sessions with your specialist will be regular and will include:
- Keeping an eating diary and advice surrounding food and eating.
- Weighing you regularly.
- Information about the ways in which anorexia damages your health.
- Help in motivating you to recover.
- Reassurance for you and your family that nobody is to blame for your anorexia. It is an illness and it is nobody's fault that you have it. It is not your fault or the fault of anyone in your family.
Examples of talking (psychological) treatments used are cognitive behavioural therapy (CBT), Maudsley Anorexia Nervosa Treatment for Adults (MANTRA), specialist supportive clinical management (SSCM) and focal psychodynamic therapy. Families are involved in therapy as much as possible, especially for young people with anorexia. Talking treatments help to look at the reasons why you may have developed anorexia. They aim to change any false beliefs that you may have about your weight and body, and to help show you how to identify and deal with emotional issues. Talking treatments take time and usually require regular sessions over several months. Treatment may also involve other members of your family going to meetings to discuss any family issues.
Treatment of any physical or teeth problems that may occur
This may include taking potassium supplements, having dental care and trying not to use laxatives or 'water' tablets (diuretics). Taking hormones may be recommended (for example, the oral contraceptive pill) to increase your body's oestrogen levels. Other tablets may be recommended to help strengthen your bones.
With treatment, anorexia can take many weeks or months to improve. It can take several years for people with anorexia to become completely better in some cases. Many people find they still have issues with food, even after treatment, but they are more in control and can lead happier, more fulfilled lives. About half of all people with anorexia (5 in 10) get completely better. About 3 in 10 improve so the anorexia has less impact on their lives, and 2 in 10 continue to live with an eating disorder.
Unfortunately, some people with anorexia die from causes related to anorexia. It is thought around 3 in every 100 people with anorexia die from it. Causes of death include infections, lack of fluid in the body (dehydration), blood chemical imbalances (such as low potassium levels) and even suicide.
Anorexia is a serious condition, so it is important to pick it up early and deal with it. If you or your family become aware there is a problem quickly, and your doctor refers you for specialist help quickly, you should have a better chance of making a full recovery.
Further reading and references
Eating disorders; NICE CKS, July 2019 (UK access only)
van Eeden AE, van Hoeken D, Hoek HW; Incidence, prevalence and mortality of anorexia nervosa and bulimia nervosa. Curr Opin Psychiatry. 2021 Nov 134(6):515-524. doi: 10.1097/YCO.0000000000000739.
Dobrescu SR, Dinkler L, Gillberg C, et al; Anorexia nervosa: 30-year outcome. Br J Psychiatry. 2020 Feb216(2):97-104. doi: 10.1192/bjp.2019.113.
Cost J, Krantz MJ, Mehler PS; Medical complications of anorexia nervosa. Cleve Clin J Med. 2020 Jun87(6):361-366. doi: 10.3949/ccjm.87a.19084.
Neale J, Hudson LD; Anorexia nervosa in adolescents. Br J Hosp Med (Lond). 2020 Jun 281(6):1-8. doi: 10.12968/hmed.2020.0099. Epub 2020 Jun 1.