What We Already Know
What are eating disorders?
Who gets eating disorders?
People with eating disorders are preoccupied with food and/or their weight and body shape, and are usually highly dissatisfied with their body and appearance. The majority of eating disorders involve low self-esteem, shame and secrecy. Anorexia nervosa, bulimia nervosa, binge eating disorder are the major eating disorders. In addition, there are many people, who do not neatly fit into any of these groups and instead have a mixture of symptoms. People with anorexia live at a low body weight, beyond the point of slimness and in an endless pursuit of thinness by restricting what they eat and sometimes compulsively over-exercising. In contrast, people with bulimia have intense cravings for food, secretively overeat and then purge to prevent weight gain (by vomiting or use of laxatives, for example). People with binge eating disorder experience distressing episodes of overeating accompanied by a feeling of loss of control, but do not engage in any reversing behaviours. Binge eating disorder often leads to obesity.
If left untreated, an eating disorder will begin to dominate an individual’s life. People with eating disorders may find it difficult to concentrate and function in education and work, they no longer enjoy leisure activities and social engagements, and often isolate themselves from friends and family. Their eating disorder becomes their one and only priority, a full time occupation. Individuals may be difficult to live with because of their distress, extreme behaviours and marked fluctuations in mood.
People with eating disorders can die as a result of the physical health problems caused by starvation or extreme weight loss behaviours. A quarter of people with eating disorders go on to develop a chronic illness. There are higher death rates among people with anorexia than among people with other psychiatric illnesses as a result of either the physical complications or suicide. The risk of death for someone with anorexia is three times higher than someone with depression, schizophrenia or alcoholism.
Why do eating disorders develop?
Anyone can develop an eating disorder, regardless of their age, sex or cultural background. Young women are most likely to develop an eating disorder, particularly those aged 15 to 25 but older women and men of all ages also get eating disorders.
Children as young as seven can develop anorexia, and there is a greater proportion of boys in this younger age group. Adolescent boys with anorexia tend to over-exercise rather than restrict their food.
What we know about the neurobiology of eating?
Research has shown that the desire to eat, and the feelings of being hungry and satisfied, are affected by a complex interplay of physiological, psychological and social factors. At times of stress and illness, it is normal for this delicate mechanism to be disrupted, leading to short-term loss or gain of appetite that returns to normal when the stress or illness has passed. Similarly, it is quite normal to alter your intake of food voluntarily for a limited period of time in order to lose or gain weight. Sometimes, however, food and eating assume an abnormal significance in people’s lives, and rather than eat in response to hunger or appetite, individuals use food and eating to help them cope with painful or uncomfortable thoughts and feelings, or with stressful situations.
Eating disorders are complex illnesses with no single cause. Psychological, interpersonal, socio-cultural and biological factors all seem to play a role, and the research of the Eating Disorders Research Group at the Institute of Psychiatry aims to understand more about the different factors and how they interact. Visit the research pages on this website to find out more about recent results and current projects.
A person is more likely to develop an eating disorder if they have low self-esteem, a tendency to be a perfectionist, or are either shy, anxious and overcontrolled or rash and impulsive in their nature. Other psychological factors are depression, boredom or loneliness. A significant proportion of people with eating disorders suffer obsessive compulsive spectrum disorders and/or have obsessive compulsive personality traits, usually dating back to childhood. These traits are found across the whole spectrum of eating disorders, but there is evidence that people with anorexia have higher levels of childhood rigidity and perfectionism than those with bulimia.
Research has shown that an individual's genetic make up may have an impact on whether they develop an eating disorder. While genetic factors may play a part in predisposing a person to developing and/or maintaining an eating disorder, these are primarily mental illnesses with a psychological basis and serious consequences, which can continue for many years if left unchecked.
People with eating disorders may find life messy, inconsistent, frightening and erratic and their eating disorder helps them to cope with life's problems, to feel more in control, and to avoid issues or emotions that are too painful to face. Anorexia makes someone feel emotionally numb, while bulimia is sometimes considered to be a way of getting rid of excess emotions. Either way, an eating disorder can help an individual deal with low self-esteem, problematic family relationships, growing up, the death of someone special, academic pressure, relationships with friends or partners, difficulties at work, school or university, a lack of self-confidence, social insecurities, sexual and emotional abuse. Some individuals may have had a harrowing, disruptive and traumatic period in their life, whereas others can think of no trigger for the development of their illness.
Research has shown that someone is more likely to develop an eating disorder if they have been brought up in an environment where food and eating, weight or body shape have assumed a disproportionate significance, or if they have been ridiculed because of their size or weight. Someone is more likely to develop an eating disorder if they have been brought up in an over-protective or over-controlling environment, where independence has not been encouraged and where they have not been encouraged to think for themselves. Other risk factors include a difficulty expressing feelings and emotions; family disharmony and troubled interpersonal relationships; a history of sexual and/or physical abuse; unrealistic family expectations for achievement; and a tendency to comply with other people's demands.
There are socio-cultural factors in the development of eating disorders which include cultural pressures that place high value on thinness and obtaining the 'perfect' body; cultural norms that emphasise physical appearance rather than inner strengths and qualities; and persistent and pervasive media messages encouraging dieting.
Research is also examining potential biological factors. It has been found that some people with eating disorders have imbalances in certain brain chemicals that control hunger, appetite and digestion. Serotonin, for example, is a chemical in the brain that affects appetite and mood. The number of receptors for this chemical varies in the brains of different individuals. This may predispose some people to have a higher sensitivity to life stress and to be calmed by eating. Others may have too much serotonin and be less anxious when they are not eating. Some people – 5% of those who are obese – have abnormal levels of melanocortin receptors in the brain. This means they are overly sensitive to appetites cues and are predisposed to overeat or binge.
What are the long-term health effects of eating disorders?
Our appetite and eating is governed by two systems in the brain, a homeostatic set of mechanisms which make us feel hungry and full in response to our body’s needs, and a hedonic mechanism that makes us desire food and feel pleasure when eating. The hormone leptin controls the homeostatic set of mechanisms. If prolonged and serious dieting results in weight loss, the amount of leptin secreted will be reduced.
In the hedonic system, the ‘wanting’ of food is moderated by homeostatic factors and is shaped by our previous experiences of food. The hedonic system is part of the brain responsible for choices about behaviour, made on the basis of reward and pleasure to be gained.
If someone fasts for a long time and essential nutrients such as protein are omitted from their diet, an intense urge to eat occurs as a result of our homeostatic system, wired to ensure our survival. This urge is caused by the action of two control mechanisms, one prompted by the composition of our bodies, in particular fat tissue (slow-acting tonic system) and the other by the gut (rapid phasic system).
If after a period of food restriction, people are exposed to highly palatable food, they over eat in response to that urge and the tendency to over consume or binge when exposed to these foods remains for several months afterwards. Underpinning these longer term changes in the brain is an imbalance in the chemical transmitters involved in the hedonic system.
We think that dieting interspersed with intermittent consumption of snacks and other highly palatable food might lead to permanent changes in the hedonic mechanism of eating.
Can eating disorders be cured?
Food deprivation can result in damage to bones, osteoporosis and fertility problems. Food deprivation and purging can result in an increased risk of cardiovascular disease, intestinal problems and kidney damage.The brain too is affected by starvation: it can lead to long term changes in metabolic and physiological processes, and changes in thoughts, feelings and behaviour.
Most of the physical problems are reversed with weight gain, or if weight control practices stop. So, it is probable that the reproductive system will return to normal if there is full recovery from anorexia, though it may take longer than normal to conceive, and in some cases it may be necessary to have hormonal treatment. It may take a long time for bones to regain their strength and thickness. Recovery may be incomplete, however, and some sites may be repaired before others. If the bones remain thin, the risk of fracture is increased. If bones in the spinal column are crushed, the spinal curvature and subsequent loss of height are irreversible: this may lead to chronic pain.
Even after recovery from an eating disorder, intestinal problems may remain. Heartburn and stomach ulcers are more common. The bowel can become ‘irritable’ with frequent diarrhoea or severe constipation. Weight control measures such as vomiting and the frequent use of laxatives alter salt and water balance and can lead to permanent kidney damage. As the kidneys have a lot of reserve function, this may not become apparent unless they are put under further stress.
If anorexia strikes before all stages of puberty have been completed, and if treatment and recovery is delayed, there may be an irreversible failure to achieve growth in stature, to achieve peak bone density and to achieve secondary sexual development.
Can eating disorders be prevented?
Recovery from an eating disorder is not easy, not short and not painless: it is a slow, long and arduous struggle full of emotional turmoil. Breaking free of an eating disorder may be the toughest challenge of an individual’s life and they need support and guidance.
Treatment involves establishing a regular and balanced eating pattern and exploring, addressing and resolving underlying emotional problems. There is a range of treatment approaches to help an individual better understand and process emotions, and new forms of treatment are constantly being developed and tested as our understanding of the different factors involved and causes increases.
We know from our research studies that early treatment is a crucial component of a full recovery, but this depends on the recognition of an eating disorder. The last person to acknowledge they have a problem will be the individual who has the eating disorder: the nature of their illness swears them to secrecy and silence. It is therefore the job of friends, family members, colleagues and health professionals to help them take the first step to recovery, to know what eating disorders are, to spot the symptoms and know how to access treatment. Between one third and one half of people who recover from eating disorders may have residual problems.
Very little research has been done in the area of prevention, although studies are being carried out to look at risk factors that might predispose a person to developing an eating disorder, and whether we can develop interventions to alter these risks. Other studies have focused on early recognition of the signs and symptoms of eating disorders to nip these in the bud before the illness becomes entrenched.
While eating disorders most commonly appear in adolescence or early adulthood, the seeds are sown much earlier. While it is impossible, at the moment, to alter genetic make up or to single-handedly tackle society’s emphasis on appearance, weight and shape, it might be helpful to encourage young people to critically appraise the messages given out by advertising and the media, and to develop their own non-competitive values of personal achievement in different spheres of life. By helping a child to develop good self-esteem, good social and coping skills, to have a realistic understanding of boundaries, both personal and external, and to encourage independence, it is possible that parents, teachers and other carers might go a long way to prevent the later development of an eating disorder. It might also help if children are encouraged to eat a balanced diet, eat regularly and not skip meals or replace them with high fat, high sugar snacks or fast foods, and if eating is seen as a time to be with others, to talk and to be sociable.