Child abuse which encompasses physical, psychological and sexual abuse, as well as neglect has been shown to approximately triple the risk of an eating disorder. Sexual abuse appears to about double the risk of bulimia; however, the association is less clear for anorexia.

Social isolation has been shown to have a deleterious effect on an individual's physical and emotional well-being. Those that are socially isolated have a higher mortality rate in general as compared to individuals that have established social relationships. This effect on mortality is markedly increased in those with pre-existing medical or psychiatric conditions, and has been especially noted in cases of coronary heart disease. "The magnitude of risk associated with social isolation is comparable with that of cigarette smoking and other major biomedical and psychosocial risk factors." (Brummett "et al.")

Social isolation can be inherently stressful, depressing and anxiety-provoking. In an attempt to ameliorate these distressful feelings an individual may engage in emotional eating in which food serves as a source of comfort. The loneliness of social isolation and the inherent stressors thus associated have been implicated as triggering factors in binge eating as well.

Waller, Kennerley and Ohanian (2007) argued that both bingeing–vomiting and restriction are emotion suppression strategies, but they are just utilized at different times. For example, restriction is used to pre-empt any emotion activation, while bingeing–vomiting is used after an emotion has been activated.

Disordered eating can represent a change in eating patterns caused by other mental disorders (e.g. clinical depression), or by factors that are generally considered to be unrelated to mental disorders (e.g. extreme homesickness).

Certain factors among adolescents tend to be associated with disordered eating, including perceived pressure from parents and peers, nuclear family dynamic, body mass index, negative affect (mood), self-esteem, perfectionism, drug use, and participation in sports that focus on leanness. These factors are similar among boys and girls alike. However, the reported incidence rates of are consistently and significantly higher in female than male participants, with 61% of females and 28% of males reporting disordered eating behaviors in a study of over 1600 adolescents.

Individual differences in the physiological stress response may also contribute to the development of emotional eating habits. Those whose adrenal glands naturally secrete larger quantities of glucocorticoids in response to a stressor are more inclined toward hyperphagia, which can act as a physiological catalyst for emotional eating. Additionally, those whose bodies require more time to clear the bloodstream of excess glucocorticoids are similarly predisposed. These biological factors can interact with environmental elements to further trigger hyperphagia, namely the type of stressor the individual is subjected to. Frequent intermittent stressors trigger repeated, sporadic releases of glucocorticoids broken up by intervals too short to allow for a complete return to baseline levels, leading to increased appetite. Those whose lifestyles or careers entail frequent intermittent stressors thus have greater biological incentive to develop patterns of emotional eating.

Anorexia nervosa has been increasingly diagnosed since 1950; the increase has been linked to vulnerability and internalization of body ideals. People in professions where there is a particular social pressure to be thin (such as models and dancers) were more likely to develop anorexia, and those with anorexia have much higher contact with cultural sources that promote weight loss. This trend can also be observed for people who partake in certain sports, such as jockeys and wrestlers. There is a higher incidence and prevalence of anorexia nervosa in sports with an emphasis on aesthetics, where low body fat is advantageous, and sports in which one has to make weight for competition. Family dynamics can play big part in the cause of anorexia. When there is a constant pressure from people to be thin, teasing, bullying can cause low self-esteem and other psychological symptoms.

As with anorexia nervosa, there is evidence of genetic predispositions contributing to the onset of this eating disorder. Abnormal levels of many hormones, notably serotonin, have been shown to be responsible for some disordered eating behaviors. Brain-derived neurotrophic factor (BDNF) is under investigation as a possible mechanism.

There is evidence that sex hormones may influence appetite and eating in women, and the onset of bulimia nervosa. Studies have shown that women with hyperandrogenism and polycystic ovary syndrome have a dysregulation of appetite, along with carbohydrates and fats. This dysregulation of appetite is also seen in women with bulimia nervosa. In addition, gene knockout studies in mice have shown that mice that have the gene encoding estrogen receptors have decreased fertility due to ovarian dysfunction and dysregulation of androgen receptors. In humans, there is evidence that there is an association between polymorphisms in the ERβ (estrogen receptor β) and bulimia, suggesting there is a correlation between sex hormones and bulimia nervosa.

Bulimia has been compared to drug addiction, though the empirical support for this characterization is limited. However, people with bulimia nervosa may share dopamine D2 receptor-related vulnerabilities with those with substance abuse disorders.

Dieting, a common behaviour in bulimics, is associated with lower plasma tryptophan levels. Decreased tryptophan levels in the brain, and thus the synthesis of serotonin, increases bulimic urges in currently and formerly bulimic individuals within hours.

Emotional eating itself may be a precursor to developing eating disorders such as binge eating or bulimia nervosa. The relationship between emotional eating and other disorders is largely due to the fact that that emotional eating and these disorders share key characteristics. More specifically, they are both related to emotion focused coping, maladaptive coping strategies, and a strong aversion to negative feelings and stimuli. It is important to note that the causal direction has not been definitively established, meaning that while emotional eating is considered a precursor to these eating disorders, it may be also be the consequence of these disorders. The latter hypothesis that emotional eating happens in response to another eating disorder is supported by research that has shown emotional eating to be more common among individuals already suffering from bulimia nervosa.

There is not one single cause of anorexia athletica, but many factors that are involved in the disorder. Research has shown that an area on chromosome 1 is linked to anorexia nervosa-sports anorexia. Thus, a person is more likely to have anorexia athletica if someone in their immediate family has had the disorder. Not only genetics, but also the environment a person is in, has a major impact on the disorder. Coaches and parents often suggest to their athlete/child to lose weight in order to perform better. Sports such as figure skating, ballet, and gymnastics promote both male and female athletes to have a thin figure. Females who partake in sports can suffer from a syndrome known as the triad. The media play a very significant role in pressuring athletes to have the ‘perfect’ body and to be thin, which can also trigger sports anorexia.

Early theories of the cause of anorexia linked it to childhood sexual abuse or dysfunctional families; evidence is conflicting, and well-designed research is needed. The fear of food is known as "sitiophobia", "cibophobia", or "sitophobia" and is part of the differential diagnosis. Other psychological causes of anorexia include low self-esteem, feeling like there is lack of control, depression, anxiety, and loneliness.

There is little data on the percentage of people with bulimia in general populations. Most studies conducted thus far have been on convenience samples from hospital patients, high school or university students. These have yielded a wide range of results: between 0.1% and 1.4% of males, and between 0.3% and 9.4% of females. Studies on time trends in the prevalence of bulimia nervosa have also yielded inconsistent results. According to Gelder, Mayou and Geddes (2005) bulimia nervosa is prevalent between 1 and 2 percent of women aged 15–40 years. Bulimia nervosa occurs more frequently in developed countries and in cities, with one study finding that bulimia is five times more prevalent in cities than in rural areas. There is a perception that bulimia is most prevalent amongst girls from middle-class families; however, in a 2009 study girls from families in the lowest income bracket studied were 153 percent more likely to be bulimic than girls from the highest income bracket.

There are higher rates of eating disorders in groups involved in activities which idealize a slim physique, such as dance, gymnastics, modeling, cheerleading, running, acting, swimming, diving, rowing and figure skating. Bulimia is thought to be more prevalent among Caucasians; however, a more recent study showed that African-American teenage girls were 50 percent more likely than white girls to exhibit bulimic behavior, including both binging and purging.

The combination of self-starvation and alcohol abuse can lead to an array of physical and psychological consequences. For example, drinking in a state of malnutrition can predispose individuals to a higher rate of blackouts, alcohol poisoning, alcohol-related injury, violence, or illness. Drinking on an empty stomach allows ethanol to reach the blood system at a swifter pace and raises one's blood alcohol content with an often dangerous speed. This can render the drinker more vulnerable to alcohol-related brain damage. In addition, alcohol abuse can have a detrimental impact on hydration and the body's retention of minerals and nutrients, further exacerbating the consequences of malnutrition and denigrating an individual's cognitive faculties. This can ultimately have a negative impact on academic performance.

These harmful consequences can be more easily induced in women, as women are oftentimes less capable of metabolizing alcohol than men. On CBS News, Carrie Wilkins, PhD, of the Center for Motivation and Change (a private practice group based in New York City) describes how women are more vulnerable to particular toxic side effects of alcohol consumption.

Drunkorexia can lead to short term and long term cognitive problems including difficulty concentrating and difficulty making decisions. It also increases the risk of developing more serious eating disorders or alcohol abuse problems. As binge drinking is involved there is a greater risk for violence, risky sexual behavior, alcohol poisoning, substance abuse and chronic disease later in life.

Few studies to date have examined OSFED prevalence. The largest community study is by Stice (2013), who examined 496 adolescent females who completed annual diagnostic interviews over 8 years. Lifetime prevalence by age 20 for OSFED overall was 11.5%. 2.8% had atypical AN, 4.4% had subthreshold BN, 3.6% had subthreshold BED, and 3.4% had purging disorder. Peak age of onset for OSFED was 18–20 years. NES was not assessed in this study, but estimates from other studies suggest that it presents in 1% of the general population.

A few studies have compared the prevalence of EDNOS and OSFED and found that though the prevalence of atypical eating disorders decreased with the new classification system, the prevalence still remains high. For example, in a population of 215 young patients presenting for ED treatment, the diagnosis of EDNOS to OSFED decreased from 62.3% to 32.6%. In another study of 240 females in the U.S. with a lifetime history of an eating disorder, the prevalence changed from 67.9% EDNOS to 53.3% OSFED. Although the prevalence appears to reduce when using the categorizations of EDNOS vs. OSFED, a high proportion of cases still receive diagnoses of atypical eating disorders, which creates difficulties in communication, treatment planning, and basic research.

Disordered eating among athletes, particularly female athletes, has been the subject of much research. In one study, women with disordered eating were 3.6 times as likely to have an eating disorder if they were athletes. In addition, female collegiate athletes who compete in heavily body conscious sports like gymnastics, swimming, or diving are shown to be more at risk for developing an eating disorder. This is a result of the engagement in sports where weekly repeated weigh-ins are standard, and usually required by coaches.

A study published in "Eating Behaviors" examined the pressure of mandated weigh-ins on female collegiate athletes and how that pressure was dealt with in terms of weight management. After analyzing over 400 survey responses, it was found that athletes reported increased uses of diet pills/ laxatives, consuming less calories than needed for their sport, and following nutrition information from unqualified sources. 75% of the weighed athletes reported using a weight-management method such as restricting food intake, increasing exercise, eating low fat foods, taking laxatives, vomiting, and other.

These habits were found to be worse in athletes that were weighed in front of their peers than those weighed in private. In addition, especially in gymnasts, preoccupation and anxiety about gaining weight and being weighed, and viewing food as the enemy were prevalent mindsets. This harmful mindset continued even after the gymnasts were retired from their sport: “Although retired, these gymnasts were still afraid to step onto a scale, were anxious about gaining weight…suggesting that the negative effects of being weighed can linger…[and] suggest[ing] that the weight/ fitness requirements acted as a socio-cultural pressure that would substantially increase the women’s risk of developing an disordered eating in the future.”

Disordered eating, along with amenorrhea and bone demineralization, form what clinicians refer to as the female athletic triad, or FAT. In contribution to these eating disorders that these female athletes develop, Results in the lack of nutrition. This can lead to the loss of several or more consecutive periods which then leads to calcium and bone loss, putting the athlete at great risk of fracturing bones and damaging tissues. Each of these conditions is a medical concern as they create serious health risks that may be life threatening to the individual. While any female athlete can develop the triad, adolescent girls are considered most at risk because of the active biological changes and growth spurts that they experience, rapidly changing life circumstances that are observed within the teenage years, and peer and social pressures.

As with other eating disorders, binge eating is an "expressive disorder"—a disorder that is an expression of deeper psychological problems. People who suffer from binge eating disorder have been found to have higher weight bias internalization, which includes low self-esteem, unhealthy eating patterns, and general body dissatisfaction. Binge eating disorder commonly develops as a result or side effect of depression, as it is common for people to turn to comfort foods when they are feeling down.

There was resistance to give binge eating disorder the status of a fully fledged eating disorder because many perceived binge eating disorder to be caused by individual choices. Previous research has focused on the relationship between body image and eating disorders, and concludes that disordered eating might be linked to rigid dieting practices. In the majority of cases of anorexia, extreme and inflexible restriction of dietary intake leads at some point to the development of binge eating, weight regain, bulimia nervosa, or a mixed form of eating disorder not otherwise specified. Binge eating may begin when individuals recover from an adoption of rigid eating habits. When under a strict diet that mimics the effects of starvation, the body may be preparing for a new type of behavior pattern, one that consumes a large amount of food in a relatively short period of time.

However, other research suggests that binge eating disorder can also be caused by environmental factors and the impact of traumatic events. One study showed that women with binge eating disorder experienced more adverse life events in the year prior to the onset of the development of the disorder, and that binge eating disorder was positively associated with how frequently negative events occur. Additionally, the research found that individuals who had binge eating disorder were more likely to have experienced physical abuse, perceived risk of physical abuse, stress, and body criticism. Other risk factors may include childhood obesity, critical comments about weight, low self-esteem, depression, and physical or sexual abuse in childhood. A few studies have suggested that there could be a genetic component to binge eating disorder, though other studies have shown more ambiguous results. Studies have shown that binge eating tends to run in families and a twin study by Bulik, Sullivan, and Kendler has shown a, "moderate heritability for binge eating" at 41 percent. More research must be done before any firm conclusions can be drawn regarding the heritability of binge eating disorder. Studies have also shown that eating disorders such as anorexia and bulimia reduce coping abilities, which makes it more likely for those suffering to turn to binge eating as a coping strategy.

A correlation between dietary restraint and the occurrence of binge eating has been shown in some research. While binge eaters are often believed to be lacking in self-control, the root of such behavior might instead be linked to rigid dieting practices. The relationship between strict dieting and binge eating is characterized by a vicious circle. Binge eating is more likely to occur after dieting, and vice versa. Several forms of dieting include delay in eating (e.g., not eating during the day), restriction of overall calorie intake (e.g., setting calorie limit to 1,000 calories per day), and avoidance of certain types of food (e.g., "forbidden" food, such as sugar, carbohydrates, etc.) Strict and extreme dieting differs from ordinary dieting. Some evidence suggests the effectiveness of moderate calorie restriction in decreasing binge eating episodes among overweight individuals with binge eating disorder, at least in the short-term.

“In the U.S, it is estimated that 3.5% of young women and 30% to 40% of people who seek weight loss treatments, can be clinically diagnosed with binge eating disorder.”

According to the National Eating Disorder Information Centre (NEDIC), the first step for someone going through anorexia athletica is to realize their eating and exercise habits are hurting them. Once an individual has realized they have a disorder, an appointment should be made with the family doctor. A family doctor can advise further medical attention if needed. With sports anorexia, it is important to go to a dietitian as well as a personal trainer. People with sports anorexia need to learn the balance between exercise and caloric intake.

Drunkorexia is not a medically diagnosed disorder therefore there is no specific treatment. However, as drunkorexia is a combination of two different disorders, binge drinking and eating disorders such as anorexia and bulimia the treatment will need to address both.

The prevalence of BED in the general population is approximately 1-3%.

Binge eating disorder is the most common eating disorder in adults.

The limited amount of research that has been done on BED shows that rates of binge eating disorder are fairly comparable among men and women. The lifetime prevalence of binge eating disorder has been observed in studies to be 2.0 percent for men and 3.5 percent for women, higher than that of the commonly recognized eating disorders anorexia nervosa and bulimia nervosa.

Rates of binge eating disorder have also been found to be similar among black women, white women, and white men, while some studies have shown that binge eating disorder is more common among black women than among white women.

Though the research on binge eating disorders tends to be concentrated in North America, the disorder occurs across cultures, In the USA, BED is present in 0.8% of male adults and 1.6% of female adults in a given year.

Additionally, 30 to 40 percent of individuals seeking treatment for weight-loss can be diagnosed with binge eating disorder.

Specific food avoidances could be caused by food phobias that cause great anxiety when a person is presented with new or feared foods. Most eating disorders are related to a fear of gaining weight. Those who suffer from ARFID do not have this fear, but the psychological symptoms and anxiety created is similar. Some sufferers of ARFID have fears such as Emetophobia (fear of vomiting) or a fear of choking.

Although EDNOS (formerly called atypical eating disorder) was originally introduced in "DSM-III" to capture unusual cases, it accounts for up to 60% of cases in eating disorder specialty clinics. EDNOS is an especially prevalent category in populations that have received inadequate research attention such as young children, males, ethnic minorities, and non-Western groups.

Clinicians will often follow a diagnostic checklist to test whether or not an individual is exhibiting behaviors and characteristics that may lead to a diagnosis of ARFID. Clinicians will look at the variety of foods an individual consumes, as well as the portion size of accepted foods. They will also question how long the avoidance or refusal of particular foods has lasted, and if there are any associated medical concerns, such as malnutrition. Unlike most eating disorders, there may be a higher rate of ARFID in young boys, than there is in young girls.

A review on behavioral addictions listed the estimated the lifetime prevalence rate (i.e., the proportion of individuals in the population that developed the disorder during their lifetime) for food addiction in the United States as 2.8%.

The psychological and mental effects can prove intense and plague an individual for years. These include hopelessness, powerlessness, isolation, shame, depression, self-loathing, guilt, suicidal thoughts, suicide attempts, and/or self-injurious behaviors.

The five OSFED examples that can be considered eating disorders include atypical AN, BN (of low frequency and/or limited duration), BED (of low frequency and/or limited duration), purging disorder, and NES. Of note, OSFED is not limited to these five examples, and can include individuals with heterogeneous eating disorder presentations (i.e., OSFED-other). Another term, Unspecified Feeding or Eating Disorder (UFED), is used to describe individuals for whom full diagnostic criteria are not met but the reason remains unspecified or the clinician does not have adequate information to make a more definitive diagnosis.

- Atypical Anorexia Nervosa: In atypical AN, individuals meet all of the criteria for AN, with the exception of the weight criterion: the individual's weight remains within or above the normal range, despite significant weight loss.

- Atypical Bulimia Nervosa: In this sub-threshold version of BN, individuals meet all criteria for BN, with the exception of the frequency criterion: binge eating and inappropriate compensatory behaviors occur, on average, less than once a week and/or for fewer than 3 months.

- Binge-eating disorder (of low frequency and/or limited duration): In this sub-threshold version of BED, individuals must meet all criteria for BED, with the exception of the frequency criterion: binge eating occurs, on average, less than once a week and/or for fewer than 3 months.

- Purging Disorder: In purging disorder, purging behavior aimed to influence weight or shape is present, but in the absence of binge eating.

- Night Eating Syndrome: In NES, individuals have recurrent episodes of eating at night, such as eating after awakening from sleep or excess calorie intake after the evening meal. This eating behavior is not culturally acceptable by group norms, such as the occasional late-night munchies after a gathering. NES includes an awareness and recall of the eating, is not better explained by external influences such as changes in the individual's sleep-wake cycle, and causes significant distress and/or impairment of functioning. Though not defined specifically in "DSM-5", research criteria for this diagnosis proposed adding the following criteria (1) the consumption of at least 25% of daily caloric intake after the evening meal and/or (2) evening awakenings with ingestions at least twice per week.

The prevalence of pica is difficult to establish because of differences in definition and the reluctance of patients to admit to abnormal cravings and ingestion, thus leading to the prevalence recordings of pica among at-risk groups being in the range of 8% and 65% depending on the study. Based on compiled self-report and interview data of pregnant and postpartum women, Pica is most prevalent geographically in Africa, with an estimated prevalence of 44.8%, followed by North and South America (23.0%) and Eurasia (17.5%). Factors associated with Pica in this population were determined to be anemia and low levels of education, both of which are associated with low socioeconomic backgrounds. Two studies of adults with intellectual disability living in institutions found that 21.8% and 25.8% of these groups suffered from pica.

Prevalence rates for children are unknown. Young children commonly place non-nutritious material into the mouth. This activity occurs in 75% of 12-month-old infants, and 15% of two-to-three-year-old children.

In institutionalized children with mental retardation, pica occurs in 10–33%.

Typically the eating is done rapidly and a person will feel emotionally numb and unable to stop eating.

Most people who have eating binges try to hide this behavior from others, and often feel ashamed about being overweight or depressed about their overeating. Although people who do not have any eating disorder may occasionally experience episodes of overeating, frequent binge eating is often a symptom of an eating disorder.

Binge-eating disorder, as the name implies, is characterized by uncontrollable, excessive eating, followed by feelings of shame and guilt. Unlike those with bulimia, those with binge-eating disorder symptoms typically do not purge their food, fast, or excessively exercise to compensate for binges. Additionally, these individuals tend to diet more often, enroll in weight-control programs and have a history of family obesity. However, many who have bulimia also have binge-eating disorder.

→Swollen of salivary glands lead to the change of facial shape

→If gastric juice is flown to the esophagus constantly, it will lead to a corrosion of the wall of esophagus(long term harmful effect)

→If gastric juice is flown to the oral cavity, it will lead to a corrosion of the oral tissue, dissolve the enamel and consequently cause the loss of teeth/increase chances for tooth decay