There are many causes of eating disorders, including biological, psychological, and/or environmental abnormalities. Many people with eating disorders suffer also from body dysmorphic disorder, altering the way a person sees himself or herself. Studies have found that a high proportion of individuals diagnosed with body dysmorphic disorder (BDD) also had some type of eating disorder, with 15% of individuals having either anorexia nervosa (AN) or bulimia nervosa. This link between body dysmorphic disorder and anorexia stems from the fact that both BDD and anorexia nervosa are characterized by a preoccupation with physical appearance and a distortion of body image. There are also many other possibilities such as environmental, social and interpersonal issues that could promote and sustain these illnesses. Also, the media are oftentimes blamed for the rise in the incidence of eating disorders due to the fact that media images of idealized slim physical shape of people such as models and celebrities motivate or even force people to attempt to achieve slimness themselves. The media is accused of distorting reality, in the sense that people portrayed in the media are either naturally thin and thus unrepresentative of normality or unnaturally thin by forcing their bodies to look like the ideal image by putting excessive pressure on themselves to look a certain way. While past findings have described the causes of eating disorders as primarily psychological, environmental, and sociocultural, new studies have uncovered evidence that there is a prevalent genetic/heritable aspect of the causes of eating disorders.
Genetic: Numerous studies have been undertaken that show a possible genetic and heritable predisposition toward eating disorders. Recent twin studies have found slight instances of genetic variance when considering the different criterion of both anorexia nervosa and bulimia nervosa as endophenotypes contributing to the disorders as a whole. In another recent study, twin and family studies led researchers to discover a genetic link on chromosome 1 that can be found in multiple family members of an individual with anorexia nervosa, indicating an inheritance pattern found between family members of others that have been previously diagnosed with an eating disorder. A study found that an individual who is a first degree relative of someone who has suffered or currently suffers from an eating disorder is seven to twelve times more likely to suffer from an eating disorder themselves. Twin studies also have shown that at least a portion of the vulnerability to develop eating disorders can be inherited, and there has been sufficient evidence to show that there is a genetic locus that shows susceptibility for developing anorexia nervosa.
Epigenetics: Epigenetic mechanisms are means by which environmental effects alter gene expression via methods such as DNA methylation; these are independent of and do not alter the underlying DNA sequence. They are heritable, but also may occur throughout the lifespan, and are potentially reversible. Dysregulation of dopaminergic neurotransmission due to epigenetic mechanisms has been implicated in various eating disorders. One study has found that “epigenetic mechanisms may contribute to the known alterations of ANP homeostasis in women with eating disorders.”
Biochemical: Eating behavior is a complex process controlled by the neuroendocrine system, of which the Hypothalamus-pituitary-adrenal-axis (HPA axis) is a major component. Dysregulation of the HPA axis has been associated with eating disorders, such as irregularities in the manufacture, amount or transmission of certain neurotransmitters, hormones or neuropeptides and amino acids such as homocysteine, elevated levels of which are found in AN and BN as well as depression.
- Serotonin: A neurotransmitter involved in depression and also has an inhibitory effect on eating behavior.
- Norepinephrine: A neurotransmitter and a hormone; abnormalities in either capacity may affect eating behavior.
- Dopamine: A precursor of norepinephrine and epinephrine and is also a neurotransmitter which regulates the rewarding property of food.
- Neuropeptide Y also known as NPY is a hormone that encourages eating and decreases metabolic rate. Blood levels of NPY are elevated in patients with anorexia nervosa, and studies have shown that injection of this hormone into the brain of rats with restricted food intake increases their time spent running on a wheel. Normally the hormone stimulates eating in healthy patients, but under conditions of starvation, it increases their activity rate, probably to increase the chance of finding food. The increased levels of NPY in the blood of patients with eating disorders can in some ways explain the instances of extreme over-exercising found in most anorexia nervosa patients.
Leptin and Ghrelin: Leptin is a hormone produced primarily by the fat cells in the body; it has an inhibitory effect on appetite by inducing a feeling of satiety. Ghrelin is an appetite-inducing hormone produced in the stomach and the upper portion of the small intestine. Circulating levels of both hormones are an important factor in weight control. While often associated with obesity, both hormones and their respective effects have been implicated in the pathophysiology of anorexia nervosa and bulimia nervosa. Leptin can also be used to distinguish between constitutional thinness found in a healthy person with a low BMI and an individual with anorexia nervosa.
Gut bacteria and immune system: Studies have shown that a majority of patients with anorexia and bulimia nervosa have elevated levels of autoantibodies that affect hormones and neuropeptides that regulate appetite control and the stress response. There may be a direct correlation between autoantibody levels and associated psychological traits. Other studies revealed that autoantibodies reactive with alpha-MSH are, in fact, generated against ClpB, a protein produced by certain gut bacteria e.g. Escherichia coli. ClpB protein was identified as a conformational antigen-mimetic of alpha-MSH. In patients with eating disorders plasma levels of anti-ClpB IgG and IgM correlated with patients’ psychological traits.
Infection: PANDAS, is an abbreviation for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus Infections. Children with PANDAS have obsessive-compulsive disorder (OCD) and/or tic disorders such as Tourette syndrome, and in whom symptoms worsen following infections such as “strep throat” and scarlet fever. There is a possibility that PANDAS may be a precipitating factor in the development of anorexia nervosa in some cases.
Lesions: Studies have shown that lesions to the right frontal lobe or temporal lobe can cause the pathological symptoms of an eating disorder.
Tumors: Tumors in various regions of the brain have been implicated in the development of abnormal eating patterns.
Brain calcification: A study highlights a case in which prior calcification of the right thalamus may have contributed to development of anorexia nervosa.
Obstetrics complications: There have been studies done which show maternal smoking, obstetrics and perinatal complications such as maternal anemia, very pre-term birth (32
Eating disorders are classified as Axis I disorders in the Diagnostic and Statistical Manual of Mental Health Disorders (DSM-IV) published by the American Psychiatric Association. There are various other psychological issues that may factor into eating disorders, some fulfill the criteria for a separate Axis I diagnosis or a personality disorder which is coded Axis II and thus are considered comorbid to the diagnosed eating disorder. Axis II disorders are subtyped into 3 “clusters”: A, B and C. The causality between personality disorders and eating disorders has yet to be fully established. Some people have a previous disorder, which may increase their vulnerability to developing an eating disorder. Some develop them afterwards. The severity and type of eating disorder symptoms have been shown to affect comorbidity. The DSM-IV should not be used by laypersons to diagnose themselves, even when used by professionals there has been considerable controversy over the diagnostic criteria used for various diagnoses, including eating disorders. There has been controversy over various editions of the DSM including the latest edition, DSM-V (May 2013).
There are various childhood personality traits associated with the development of eating disorders. During adolescence these traits may become intensified due to a variety of physiological and cultural influences such as the hormonal changes associated with puberty, stress related to the approaching demands of maturity and sociocultural influences and perceived expectations, especially in areas that concern body image. Many personality traits have a genetic component and are highly heritable. Maladaptive levels of certain traits may be acquired as a result of anoxic or traumatic brain injury, neurodegenerative diseases such as Parkinson’s disease, neurotoxicity such as lead exposure, bacterial infection such as Lyme disease or viral infection such as Toxoplasma gondii as well as hormonal influences. While studies are continuing via the use of various imaging techniques, such as fMRI, these traits have been shown to originate in various regions of the brain such as the amygdala and the prefrontal cortex. Disorders in the prefrontal cortex and the executive functioning system have been shown to affect eating behavior.
Child abuse, which encompasses physical, psychological, and sexual abuse, as well as neglect, has been shown by innumerable studies to be a precipitating factor in a wide variety of psychiatric disorders, including eating disorders. Children who are subjected to abuse may develop eating disorders in an effort to gain some sense of control or for a sense of comfort, or they may be in an environment where the diet is unhealthy or insufficient. Child abuse and neglect can cause profound changes in both the physiological structure and the neurochemistry of the developing brain. Children who, as wards of the state, were placed in orphanages or foster homes are especially susceptible to developing a disordered eating pattern. In a study done in New Zealand, 25% of the study subjects in foster care exhibited an eating disorder. An unstable home environment is detrimental to the emotional well-being of children, even in the absence of blatant abuse or neglect, the stress of an unstable home can contribute to the development of an eating disorder.
Parental influence has been shown to be an intrinsic component in the development of eating behaviors of children. This influence is manifested and shaped by a variety of diverse factors such as familial genetic predisposition, dietary choices as dictated by cultural or ethnic preferences, the parents’ own body shape and eating patterns, the degree of involvement and expectations of their children’s eating behavior as well as the interpersonal relationship of parent and child. This is in addition to the general psychosocial climate of the home and the presence or absence of a nurturing stable environment. It has been shown that maladaptive parental behavior has an important role in the development of eating disorders. As to the more subtle aspects of parental influence, it has been shown that eating patterns are established in early childhood and that children should be allowed to decide when their appetite is satisfied as early as the age of two. A direct link has been shown between obesity and parental pressure to eat more.
Coercive tactics in regard to diet have not been proven to be efficacious in controlling a child’s eating behavior. Affection and attention have been shown to affect the degree of a child’s finickiness and their acceptance of a more varied diet. Hilde Bruch, a pioneer in the field of studying eating disorders, asserts that anorexia nervosa often occurs in girls who are high achievers, obedient, and always trying to please their parents. Those parents have a tendency to be over-controlling and fail to encourage the expression of emotions, inhibiting daughters from accepting their own feelings and desires. Adolescent females in these overbearing families lack the ability to be independent from their families, yet realize the need to, often resulting in rebellion. Controlling their food intake may make them feel better, as it provides them with a sense of control.
In various studies such as one conducted by The McKnight Investigators, peer pressure was shown to be a significant contributor to body image concerns and attitudes toward eating among subjects in their teens and early twenties. Eleanor Mackey and co-author, Annette M. La Greca of the University of Miami, studied 236 teen girls from public high schools in southeast Florida. “Teen girls’ concerns about their own weight, about how they appear to others and their perceptions that their peers want them to be thin are significantly related to weight-control behavior,” says psychologist Eleanor Mackey of the Children’s National Medical Center in Washington and lead author of the study. “Those are really important.” According to one study, 40% of 9- and 10-year-old girls are already trying to lose weight.
Such dieting is reported to be influenced by peer behavior, with many of those individuals on a diet reporting that their friends also were dieting. The number of friends dieting and the number of friends who pressured them to diet also played a significant role in their own choices. Elite athletes have a significantly higher rate in eating disorders. Female athletes in sports such as gymnastics, ballet, diving, etc. are found to be at the highest risk among all athletes. Women are more likely than men to acquire an eating disorder between the ages of 13–30 and < 15% of those with bulimia and anorexia are men.
There is a cultural emphasis on thinness, which is especially pervasive in western society. There is an unrealistic stereotype of what constitutes beauty and the ideal body type as portrayed by the media, fashion, and entertainment industries. “The cultural pressure on men and women to be ‘perfect’ is an important predisposing factor for the development of eating disorders.” Furthermore, when women of all races base their evaluation of their self upon what is considered the culturally ideal body, the incidence of eating disorders increases. Eating disorders are becoming more prevalent in non-Western countries where thinness is not seen as the ideal, showing that social and cultural pressures are not the only causes of eating disorders. For example, observations of anorexia in all of the non-Western regions of the world point to the disorder not being “culture-bound” as once thought. However, studies on rates of bulimia suggest that it might be culturally bound.
In non-Western countries, bulimia is less prevalent than anorexia, but these non-Western countries where it is observed can be said to have probably or definitely been influenced or exposed to Western culture and ideology. Socioeconomic status (SES) has been viewed as a risk factor for eating disorders, presuming that possessing more resources allows an individual to actively choose to diet and reduce body weight. Some studies have also shown a relationship between increasing body dissatisfaction with increasing SES. However, once high socioeconomic status has been achieved, this relationship weakens and, in some cases, no longer exists.
The media plays a major role in the way in which people view themselves. Countless magazine ads and commercials depict rail thin celebrities like Lindsay Lohan, Nicole Richie and Mary Kate Olsen, who appear to gain nothing but attention from their looks. Society has taught people that being accepted by others is necessary at all costs. Unfortunately, this has led to the belief that in order to fit in one must look a certain way. Televised beauty competitions such as the Miss America Competition contribute to the idea of what it means to be beautiful because competitors are evaluated on the basis of their opinion.
In addition to socioeconomic status, being considered a cultural risk factor so is the world of sports. Athletes and eating disorders tend to go hand in hand, especially the sports where weight is a competitive factor. Gymnastics, horseback riding, wrestling, bodybuilding, and dancing are just a few that fall into this category of weight dependent sports. Eating disorders among individuals that participate in competitive activities, especially women, often lead to having physical and biological changes related to their weight that often mimic prepubescent stages. Oftentimes as women’s bodies change they lose their competitive edge which leads them to taking extreme measures to maintain their younger body shape.
Men often struggle with binge eating followed by excessive exercise while focusing on building muscle rather than losing fat, but this goal of gaining muscle is just as much an eating disorder as obsessing over thinness. The following statistics taken from Susan Nolen-Hoeksema’s book, (ab) normal psychology, shows the estimated percentage of athletes that struggle with eating disorders based on the category of sport.
Aesthetic sports (dance, figure skating, gymnastics) – 35%
Weight dependent sports (judo, wrestling) – 29%
Endurance sports (cycling, swimming, running) – 20%
Technical sports (golf, high jumping) – 14%
Ball game sports (volleyball, soccer) – 12%
Although most of these athletes develop eating disorders to keep their competitive edge, others use exercise as a way to maintain their weight and figure. This is just as serious as regulating food intake for competition. Even though there is mixed evidence showing at what point athletes are challenged with eating disorders, studies show that regardless of competition level, all athletes are at higher risk for developing eating disorders that non-athletes, especially those that participate in sports where thinness is a factor. Pressure from society is also seen within the homosexual community. Homosexual men are at greater risk of eating disorder symptoms than heterosexual men. Within the gay culture, muscularity gives the advantages of both social and sexual desirability and power.
These pressures and ideas that another homosexual male may desire a mate who is thinner or muscular can possibly lead to eating disorders. The higher eating disorder symptom score reported, the more concern about how others perceive them and the more frequent and excessive exercise sessions occur. High levels of body dissatisfaction are also linked to external motivation to working out and old age; however, having a thin and muscular body occurs within younger homosexual males than older. It is important to realize some of the limitations and challenges of many studies that try to examine the roles of culture, ethnicity, and SES. For starters, most of the cross-cultural studies use definitions from the DSM-IV-TR, which has been criticized as reflecting a Western cultural bias. Therefore, assessments and questionnaires may not be constructed to detect some of the cultural differences associated with different disorders. Also, when looking at individuals in areas potentially influenced by Western culture, few studies have attempted to measure how much an individual has adopted the mainstream culture or retained the traditional cultural values of the area. Lastly, the majority of the cross-cultural studies on eating disorders and body image disturbances occurred in Western nations and not in the countries or regions being examined.
While there are many influences to how an individual processes their body image, the media does play a major role. Along with the media, parental influence, peer influence, and self-efficacy beliefs also play a large role in an individual’s view of themselves. The way the media presents images can have a lasting effect on an individual’s perception of their body image. Eating disorders are a worldwide issue and while women are more likely to be affected by an eating disorder, it still affects both genders. The media has an impact on eating disorders whether shown in a positive or negative light; it then has a responsibility to use caution when promoting images that project an ideal that many turn to eating disorders.