Around one-in-250 women will suffer from anorexia at some point, while one-in-50
women will suffer from bulimia. Men also suffer from these conditions, though they are approximately five times less common.
The common feature of all eating disorders is an abnormal attitude towards food, which causes the sufferer to change their eating habits and general behaviour.
Often the sufferer will focus excessively on his or her body shape, perhaps convinced that he or she is fat when it is not the case - and leading him or her to make unhealthy choices about their eating.
What are eating disorders?
The three most common forms of eating disorder are anorexia nervosa, bulimia and binge eating.
Anorexia sees sufferers trying to keep their weight as low as possible - usually by avoiding food and exercising as much as possible.
Bulimia sufferers tend to binge eat and then try to control their weight by making themselves sick afterwards or taking laxatives.
What causes them?
The finger of blames is often pointed at social pressures and images in magazines, but there are also several more concrete risk factors which have been identified.
Having a family history of such disorders, depression or substance abuse can put an individual at risk - and people with obsessive personalities or personality disorders can also be at risk.
Many sufferers have also been criticised for their weight or eating habits in the past, while others are in professions where being skinny is valued - such as ballet dancing, modelling or certain sports.
Difficult family relationships, a history of sexual or emotional abuse, bereavement and work or school stress are also thought to serve as triggers.
What are the signs?
It's not always easy to spot if a friend or family member is suffering from an eating disorder, because they will probably be trying to hide it.
Things to watch for include missing meals, complaining of being fat when the opposite is true, repeatedly claiming they have already eaten or will eat later, feeling uncomfortable eating in public and sticking to low-calorie foods when in company.
You may wish to contact eating disorders charity beat if you suspect somebody you know may be suffering from one, the helpline number is 0845 6341414.
How are they treated?
Treatment for eating disorders can take a long time, but there are several options available - and most involve monitoring the sufferer's physical health while attempting to deal with the underlying psychological issues.
Cognitive behavioural therapy (CBT) attempts to change how the subject thinks and acts in a given situation, perhaps involving food or the way they perceive their body.
Psychotherapy attempts to deal with the issues behind the disorder by discussing them one-to-one and focusing on relationship-based issues.
Dietary counselling or anti-depressant drugs can also be used to combat certain eating disorders.
Psychodynamic therapy attempts to relate the subject's personality and life experiences to their current thoughts, feelings and behaviour.
More information about eating disorders, their treatment and recovery is available on the NHS Choices website.