These eating disorders are specified as mental disorders in standard medical manuals, such as in the ICD-10, the DSM-5, or both.

- Anorexia nervosa (AN), characterized by lack of maintenance of a healthy body weight, an obsessive fear of gaining weight or refusal to do so, and an unrealistic perception, or non-recognition of the seriousness, of current low body weight. Anorexia can cause menstruation to stop, and often leads to bone loss, loss of skin integrity, etc. It greatly stresses the heart, increasing the risk of heart attacks and related heart problems. The risk of death is greatly increased in individuals with this disease. The most underlining factor researchers are starting to take notice of is that it may not just be a vanity, social, or media issue, but it could also be related to biological and or genetic components. The DSM-5 contains many changes that better represent patients with these conditions. The DSM-IV required amenorrhea (the absence of the menstrual cycle) to be present in order to diagnose a patient with anorexia. This is no longer a requirement in the DSM-5.

- Bulimia nervosa (BN), characterized by recurrent binge eating followed by compensatory behaviors such as purging (self-induced vomiting, eating to the point of vomiting, excessive use of laxatives/diuretics, or excessive exercise). Fasting and over-exercising may also be used as a method of purging following a binge.

- Muscle dysmorphia is characterized by appearance preoccupation that one's own body is too small, too skinny, insufficiently muscular, or insufficiently lean. Muscle dysmorphia affects mostly males.

- Binge Eating Disorder (BED), characterized by recurring binge eating at least once a week for over a period of 3 months while experiencing lack of control and guilt after overeating. The disorder can develop within individuals of a wide range of ages and socioeconomic classes.

- Other Specified Feeding or Eating Disorder (OSFED) is an eating or feeding disorder that does not meet full DSM-5 criteria for AN, BN, or BED. Examples of otherwise-specified eating disorders include individuals with atypical anorexia nervosa, who meet all criteria for AN except being underweight, despite substantial weight loss; atypical bulimia nervosa, who meet all criteria for BN except that bulimic behaviors are less frequent or have not been ongoing for long enough; purging disorder; and night eating syndrome.

Symptoms and complications vary according to the nature and severity of the eating disorder:

Some physical symptoms of eating disorders are weakness, fatigue, sensitivity to cold, reduced beard growth in men, reduction in waking erections, reduced libido, weight loss and failure of growth. Unexplained hoarseness may be a symptom of an underlying eating disorder, as the result of acid reflux, or entry of acidic gastric material into the laryngoesophageal tract. Patients who induce vomiting, such as those with anorexia nervosa, binge eating-purging type or those with purging-type bulimia nervosa are at risk for acid reflux. Polycystic ovary syndrome (PCOS) is the most common endocrine disorder to affect women. Though often associated with obesity it can occur in normal weight individuals. PCOS has been associated with binge eating and bulimic behavior. Other possible manifestations are dry lips, burning tongue, parotid gland swelling, and temporomandibular disorders.

Binge eating is the core symptom of BED; however, not everyone who binge eats has BED. An individual may occasionally binge eat without experiencing many of the negative physical, psychological, or social effects of BED. This example may be considered an eating problem (or not), rather than a disorder. Precisely defining binge eating can be problematic, however binge eating episodes in BED are generally described as having the following potential features:

- Eating much faster than normal during a binge perhaps in a short space of time

- Eating until feeling uncomfortably full

- Eating a large amount when not hungry

- Subjective loss of control over how much or what is eaten

- Binges may be planned in advance, involving the purchase of special binge foods, and the allocation of specific time for binging, sometimes at night

- Eating alone or secretly due to embarrassment over the amount of food consumed

- There may be a dazed mental state during the binge

- Not being able to remember what was eaten after the binge

- Feelings of guilt, shame or disgust following a food binge

In contrast to bulimia nervosa, binge eating episodes are not regularly followed by activities intended to prevent weight gain, such as self-induced vomiting, laxative or enema misuse, or strenuous exercise. BED is characterized more by overeating than dietary restriction and over concern about body shape. Obesity is common in persons with BED, as are depressive features, low self-esteem, stress and boredom.

Bulimia typically involves rapid and out-of-control eating, which may stop when the bulimic is interrupted by another person or the stomach hurts from over-extension, followed by self-induced vomiting or other forms of purging. This cycle may be repeated several times a week or, in more serious cases, several times a day and may directly cause:

- Chronic gastric reflux after eating, secondary to vomiting

- Dehydration and hypokalemia due to renal potassium loss in the presence of alkalosis and frequent vomiting

- Electrolyte imbalance, which can lead to abnormal heart rhythms, cardiac arrest, and even death

- Esophagitis, or inflammation of the esophagus

- Mallory-Weiss tears

- Boerhaave syndrome, a rupture in the esophageal wall due to vomiting

- Oral trauma, in which repetitive insertion of fingers or other objects causes lacerations to the lining of the mouth or throat

- Russell's sign: calluses on knuckles and back of hands due to repeated trauma from incisors

- Perimolysis, or severe dental erosion of tooth enamel

- Swollen salivary glands (for example, in the neck, under the jaw line)

- Gastroparesis or delayed emptying

- Constipation

- Peptic ulcers

- Infertility

- Constant weight fluctuations are common

These are some of the many signs that may indicate whether someone has bulimia nervosa:

- A fixation on the number of calories consumed

- A fixation on and extreme consciousness of ones weight

- Low self-esteem and/or self harming

- Suicidal tendencies

- Low blood pressure

- An irregular menstrual cycle in woman

- Regular trips to the bathroom, especially soon after eating

- Depression, anxiety disorders and sleep disorders

- Frequent occurrences involving consumption of abnormally large portions of food

- The use of laxatives and diet pills

- Unhealthy/dry skin, hair, nails and lips

- A lack of energy

As with many psychiatric illnesses, delusions can occur, in conjunction with other signs and symptoms, leaving the person with a false belief that is not ordinarily accepted by others.

People with bulimia nervosa may also exercise to a point that excludes other activities.

Binge eating disorder (BED) is an eating disorder characterized by frequent and recurrent binge eating episodes with associated negative psychological and social problems, but without subsequent purging episodes (e.g. vomiting).

BED is a recently described condition, which was required to distinguish binge eating similar to that seen bulimia nervosa but without characteristic purging. Individuals who are diagnosed with bulimia nervosa and binge eating disorder exhibit similar patterns of compulsive overeating, neurobiological features of dysfunctional cognitive control and food addiction, and biological and environmental risk factors. Indeed, some consider BED a milder version of bulimia nervosa, and that the conditions are on the same spectrum.

Binge eating is one of the most prevalent eating disorders among adults, though there tends to be less media coverage and research about the disorder in comparison to anorexia nervosa and bulimia nervosa.

Bulimia nervosa can be difficult to detect, compared to anorexia nervosa, because bulimics tend to be of average or slightly above or below average weight. Many bulimics may also engage in significantly disordered eating and exercise patterns without meeting the full diagnostic criteria for bulimia nervosa. Recently, the "Diagnostic and Statistical Manual of Mental Disorders" was revised, which resulted in the loosening of criteria regarding the diagnoses of bulimia nervosa and anorexia nervosa. The diagnostic criteria utilized by the DSM-5 includes repetitive episodes of binge eating (a discrete episode of overeating during which the individual feels out of control of consumption) compensated for by excessive or inappropriate measures taken to avoid gaining weight. The diagnosis also requires the episodes of compensatory behaviors and binge eating to happen a minimum of once a week for a consistent time period of 3 months. The diagnosis is made only when the behavior is not a part of the symptom complex of anorexia nervosa and when the behavior reflects an overemphasis on physical mass or appearance. Purging often is a common characteristic of a more severe case of bulimia nervosa.

The three general categories for an EDNOS diagnosis are subthreshold symptoms of anorexia or bulimia, a mixture of both anorexia or bulimia, and eating behaviors that are not particularized by anorexia and bulimia. EDNOS is no longer considered a diagnosis in "DSM-5"; those displaying symptoms of what would previously have been considered EDNOS are now classified under Other Specified Feeding or Eating Disorder.

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.

Rather than providing specific diagnostic criteria for EDNOS, the fourth revision of the "Diagnostic and Statistical Manual of Mental Disorders" ("DSM-IV") listed six non-exhaustive example presentations, including individuals who:

1. Meet all criteria for anorexia nervosa except their weight falls within the normal range

2. Meet all criteria for bulimia nervosa except they engage in binge eating or purging behaviors less than twice per week or for fewer than three months

3. Purge after eating small amounts of food while retaining a normal body weight

4. Repeatedly chew and spit out large amounts of food without swallowing

5. Do not meet criteria for binge eating disorder

Despite its subclinical status in "DSM-IV", available data suggest that EDNOS is no less severe than the officially recognized "DSM-IV" eating disorders. In a comprehensive meta-analysis of 125 studies, individuals with EDNOS exhibited similar levels of eating pathology and general psychopathology to those with anorexia nervosa and binge eating disorder, and similar levels of physical health problems as those with anorexia nervosa. Although individuals with bulimia nervosa scored significantly higher than those with EDNOS on measures of eating pathology and general psychopathology, those with EDNOS exhibited more physical health problems than those with bulimia nervosa.

Disordered eating describes a variety of abnormal eating behaviors that, by themselves, do not warrant diagnosis of an eating disorder.

Disordered eating includes behaviors that are common features of eating disorders, such as:

- Chronic restrained eating.

- Compulsive eating.

- Binge eating, with associated loss of control.

- Self-induced vomiting.

Disordered eating also includes behaviors that are not characteristic of any eating disorder, such as:

- Irregular, chaotic eating patterns.

- Ignoring physical feelings of hunger and satiety (fullness).

- Use of diet pills.

- Emotional eating.

- Night eating.

- "Secretive food concocting": the consumption of embarrassing food combinations, such as mashed potatoes mixed with sandwich cookies. See also Food craving § Pregnancy and Nocturnal sleep-related eating disorder § Symptoms and behaviors.

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

Anorexia nervosa is an eating disorder characterized by attempts to lose weight, to the point of starvation. A person with anorexia nervosa may exhibit a number of signs and symptoms, the type and severity of which may vary and may be present but not readily apparent.

Anorexia nervosa, and the associated malnutrition that results from self-imposed starvation, can cause complications in every major organ system in the body. Hypokalaemia, a drop in the level of potassium in the blood, is a sign of anorexia nervosa. A significant drop in potassium can cause abnormal heart rhythms, constipation, fatigue, muscle damage and paralysis.

Symptoms may include:

- A low body mass index for one's age and height.

- Amenorrhea, a symptom that occurs after prolonged weight loss; causes menses to stop, hair becomes brittle, and skin becomes yellow and unhealthy.

- Fear of even the slightest weight gain; taking all precautionary measures to avoid weight gain or becoming "overweight".

- Rapid, continuous weight loss.

- Lanugo: soft, fine hair growing over the face and body.

- An obsession with counting calories and monitoring fat contents of food.

- Preoccupation with food, recipes, or cooking; may cook elaborate dinners for others, but not eat the food themselves or consume a very small portion.

- Food restrictions despite being underweight or at a healthy weight.

- Food rituals, such as cutting food into tiny pieces, refusing to eat around others and hiding or discarding of food.

- Purging: May use laxatives, diet pills, ipecac syrup, or water pills to flush food out of their system after eating or may engage in self-induced vomiting though this is a more common symptom of bulimia.

- Excessive exercise including micro-exercising, for example making small persistent movements of fingers or toes.

- Perception of self as overweight, in contradiction to an underweight reality.

- Intolerance to cold and frequent complaints of being cold; body temperature may lower (hypothermia) in an effort to conserve energy due to malnutrition.

- Hypotension or orthostatic hypotension.

- Bradycardia or tachycardia.

- Depression, anxiety disorders and insomnia.

- Solitude: may avoid friends and family and become more withdrawn and secretive.

- Abdominal distension.

- Halitosis (from vomiting or starvation-induced ketosis).

- Dry hair and skin, as well as hair thinning.

- Chronic fatigue.

- Rapid mood swings.

- Having feet discoloration causing an orange appearance.

- Having severe muscle tension + aches and pains.

- Evidence/habits of self harming or self-loathing.

- Admiration of thinner people.

Interoception has an important role in homeostasis and regulation of emotions and motivation. Anorexia has been associated with disturbances to interoception. People with anorexia concentrate on distorted perceptions of their body exterior due to fear of looking overweight. Aside from outer appearance, they also report abnormal bodily functions such as indistinct feelings of fullness. This provides an example of miscommunication between body and brain. Further, people with anorexia experience abnormally intense cardiorespiratory sensations, particularly of the breath, most prevalent before they consume a meal. People with anorexia also report inability to distinguish emotions from bodily sensations in general, called alexithymia. In addition to metacognition, people with anorexia also have difficultly with social cognition including interpreting other’s emotions, and demonstrating empathy. Abnormal interoceptive awareness like these examples have been observed so frequently in anorexia that they have become key characteristics of the illness.

Binge eating is a pattern of disordered eating which consists of episodes of uncontrollable eating. It is sometimes a symptom of binge eating disorder or compulsive overeating disorder. During such binges, a person rapidly consumes an excessive quantity of food. A diagnosis of binge eating is associated with feelings of loss of control.

Someone with anorexia athletica can experience numerous signs and symptoms, a few of which are listed below. The seriousness of the symptoms is dependent on the individual, and more symptoms come with the length the athlete excessively exercises. If anorexia athletica persists for long enough, the individual can become malnourished, which eventually leads to further complications in major organs such as the liver, kidney, heart and brain.

- Excessive exercise

- Obsessive behavior with calories, fat, and weight

- Self-worth is based on physical performance

- Enjoyment of sports is diminished or gone

- Denying the over exercising is a problem

The fifth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5) renamed "Feeding Disorder of Infancy or Early Childhood" to Avoidant/Restrictive Food Intake Disorder, and broadened the diagnostic criteria. Previously defined as a disorder exclusive to children and adolescents, the DSM-5 broadened the disorder to include adults who limit their eating and are affected by related physiological or psychological problems, but who do not fall under the definition of another eating disorder.

The DSM-5 defines the following diagnostic criteria:

- Disturbance in eating or feeding, as evidenced by one or more of:

- Substantial weight loss (or, in children, absence of expected weight gain)

- Nutritional deficiency

- Dependence on a feeding tube or dietary supplements

- Significant psychosocial interference

- Disturbance not due to unavailability of food, or to observation of cultural norms

- Disturbance not due to anorexia nervosa or bulimia nervosa, and no evidence of disturbance in experience of body shape or weight

- Disturbance not better explained by another medical condition or mental disorder, or when occurring concurrently with another condition, the disturbance exceeds what is normally caused by that condition

In previous years, the DSM was not inclusive in recognizing all of the challenges associated with feeding and eating disorders in 3 main domains:

- Eating Disorders Not Otherwise Specified (EDNOS) was an all-inclusive, placeholder group for all individuals that presented challenges with feeding

- The category of Feeding Disorder of Infancy/ Early Childhood was noted to be too broad, limiting specification when treating these behaviors

- There are children and youth who present feeding challenges but do not fit within any existing categories to date

Children are often picky eaters, this does not necessarily mean they meet the criteria for an ARFID diagnosis. In addition, self-identification as having ARFID may contribute to ARFID.

Other specified feeding or eating disorder or OSFED is the "DSM-5" category that replaces the category formerly called Eating Disorder Not Otherwise Specified (EDNOS) in "DSM-IV", and that captures feeding disorders and eating disorders of clinical severity that do not meet diagnostic criteria for anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED), avoidant/restrictive food intake disorder (ARFID), pica, or rumination disorder. OSFED includes five examples: atypical AN, BN (of low frequency and/or limited duration), BED (of low frequency and/or limited duration), purging disorder, and night eating syndrome (NES).

Sufferers of ARFID have an inability to eat certain foods. "Safe" foods may be limited to certain food types and even specific brands. In some cases, afflicted individuals will exclude whole food groups, such as fruits or vegetables. Sometimes excluded foods can be refused based on color. Some may only like very hot or very cold foods, very crunchy or hard-to-chew foods, or very soft foods, or avoid sauces.

Most sufferers of ARFID will still maintain a healthy or normal body weight. There are no specific outward appearances associated with ARFID. Sufferers can experience physical gastrointestinal reactions to adverse foods such as retching, vomiting or gagging. Some studies have identified symptoms of social avoidance due to their eating habits. Most, however, would change their eating habits if they could.

A food addiction features compulsive overeating, such as binge eating behavior, as its core and only defining feature. There are several potential signs that a person may be suffering from compulsive overeating. Common behaviors of compulsive overeaters include eating alone, consuming food quickly, and gaining weight rapidly, and eating to the point of feeling sick to the stomach. Other signs include significantly decreased mobility and the withdrawal from activities due to weight gain. Emotional indicators can include feelings of guilt, a sense of loss of control, depression and mood swings.

Hiding consumption is an emotional indicator of other symptoms that could be a result of having a food addiction. Hiding consumption of food includes eating in secret; late at night while everybody else is asleep, in the car, and hiding certain foods until ready to consume in private. Other signs of hiding consumption are avoiding social interactions to eat the specific foods that are craved. Other emotional indicators are Inner guilt; which includes making up excuses to why the palatable food would be beneficial to consume, and then feeling guilty about it shortly after consuming.

Sense of loss of control is indicated in many ways which includes, going out of the way to obtain specific foods, spending unnecessary amounts of money on foods to satisfy cravings. Difficulty concentrating on things such as a job or career can indicate sense of loss of control by not being to organize thoughts leading to a decrease in efficiency. Other ways to indicate the sense of loss of control, are craving food despite being full. One may set rules to try to eat healthy but the cravings over rule and the rules are failed to be followed. One big indicator of loss of control due to food addiction is even though one knows they have a medical problem caused by the craved foods, they cannot stop consuming the foods, which can be detrimental to their health.

Food addiction has some physical signs and symptoms. Decreased energy; not being able to be as active as in the past, not being able to be as active as others around, also a decrease in efficiency due to the lack of energy. Having trouble sleeping; being tired all the time such as fatigue, oversleeping, or the complete opposite and not being able to sleep such as insomnia. Other physical signs and symptoms are restlessness, irritability, digestive disorders, and headaches.

In extreme cases food addiction can result in some suicidal thoughts.

A Food addiction, especially long-term, can result in negative consequences to all aspects of a person’s life, creating damaging and chronic symptoms.

Purging disorder is an eating disorder characterized by recurrent purging (self-induced vomiting, misuse of laxatives, diuretics, or enemas) to control weight or shape in the absence of binge eating episodes.

Purging disorder differs from bulimia nervosa (BN) because individuals with purging disorder do not consume a large amount of food before they purge. In current diagnostic systems, purging disorder is a form of Other specified feeding or eating disorder (OSFED). Research indicates that purging disorder may be as common as bulimia nervosa or anorexia nervosa in women, that the syndrome is associated with clinically significant levels of distress, and that it appears to be distinct from bulimia nervosa on measures of hunger and ability to control food intake. Some of the signs of purging disorder are frequent trips to the bathroom directly after a meal, frequent use of laxatives, and obsession over one's appearance and weight. Other signs include swollen cheeks, popped blood vessels in the eyes, and clear teeth which are all signs of excessive vomiting.

Exercise Bulimia can sometimes go unnoticed because exercise is something that is seen as healthy, but just because a person looks healthy does not mean they are. Compulsive exercisers will often schedule their lives around exercise just as those with eating disorders schedule their lives around eating (or not eating). Other indications of compulsive exercise are:

- Missing work, school and other important events in order to work out

- Working out with an injury or while sick

- Working out secretly or away from noticeable sight

- Becoming unusually depressed if unable to exercise

- Working out for hours at a time each day

- Not taking any rest or recovery days

- Defining self-worth in terms of performance

- Justifies excessive behavior by defining self as a "special" elite athlete

- Depression or agitation when unable to work out

- Amenorrhea, the stop of a woman's menstrual cycle

- Isolation from others while working out

- Lack of interest in friends and eating

- Lack of sleep

NES is sometimes comorbid with excess weight; as many as 28% of individuals seeking gastric bypass surgery were found to suffer from NES in one study. However, not all individuals with NES are overweight. Night eating has been associated with diabetic complications. Many people with NES also experience depressed mood and anxiety disorders.

The differential diagnoses of anorexia nervosa (AN) includes various types of medical and psychological conditions, which may be misdiagnosed as AN. In some cases, these conditions may be comorbid with AN because the misdiagnosis of AN is not uncommon. For example, a case of achalasia was misdiagnosed as AN and the patient spent two months confined to a psychiatric hospital. A reason for the differential diagnoses that surround AN arise mainly because, like other disorders, it is primarily, albeit defensively and adaptive for, the individual concerned.

Anorexia Nervosa is a psychological disorder characterized by extremely reduced intake of food. People suffering from Aneroxia Nervosa have a low self-image and consider themselves overweight.

Common behaviors and signs of someone suffering from AN:

- Forcing oneself to vigorously exercise even in adverse conditions or when their health does not permit it.

- Forcing own self to urinate and excrete waste product from the body.

- Using substituted amphetamines (stimulants that can reduce appetite) to reduce appetite.

- Skin turning yellow

Emotional eating is defined as overeating in order to relieve negative emotions. Thus, emotional eating is considered a maladaptive coping strategy. If an individual frequently engages in emotional eating, it can increase the risk of developing other eating disorders, like bulimia and anorexia nervosa. Research has also shown that the presence of an existing eating disorder increases the likelihood that an individual will engage in emotional eating. Given the relationship between serious eating disorders and emotional eating behavior, it is important for clinical psychologists and nutritionists to recognize the signs of emotional eating and provide individuals with treatment. Since emotional eating is utilized to manage negative emotions, treatment necessitates learning healthy and more effective coping strategies.