Avoidant-Restrictive Food Intake Disorder, commonly known as ARFID is a persistent feeding or eating disturbance manifested by avoidance of food or restrictive food intake that is not caused by food scarcity, cultural or religious practices, or some other psychological or medical disorder. It results in significant weight loss or nutritional deficiency, dependence on tube feeding or nutritional supplements, and/or impairment in psychosocial functioning.  Unlike anorexia nervosa and bulimia nervosa, ARFID is not characterized by a preoccupation with body shape and weight or by intentional weight loss behaviors.  Instead, patients suffering from ARFID may be disinterested in food and eating, or may avoid foods because of a negative response to their color, texture, smell, taste or temperature. Individuals may also excessively fear unpleasant consequences of eating such as choking, gagging or vomiting (functional dysphagia) or exacerbated gastroesophageal reflux symptoms. 
Using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), patients exhibiting some or all of the symptoms described above were often diagnosed with an Eating Disorder Not Otherwise Specified (EDNOS) or with Feeding Disorder of Infancy and Early Childhood. EDNOS was a catch-all category that included eating disorder patients who did not meet criteria for Anorexia Nervosa, Bulimia Nervosa, or any other specific eating disorder. Diagnoses of EDNOS were common. In fact, more than 50 percent of children and adolescents presenting to eating disorder clinics received the non-specific EDNOS diagnosis,  which may have resulted in inadequate management of their illness.
To enhance the clinical utility of the DSM and develop more targeted treatment approaches for eating disorder patients who are not diagnosed with Anorexia Nervosa, Bulimia Nervosa, or some other specific eating disorder, the DSM-5 Eating Disorders Work Group developed criteria that could be used to characterize EDNOS patients more discretely and could be extended to apply across the lifespan of patients. 
In line with that effort, the DSM-5 Eating Disorder Work Group considered the shortcomings of the DSM-IV-TR diagnosis of Feeding Disorder of Infancy or Early Childhood, a diagnosis that was given to children 6 years of age and younger who presented with a feeding disturbance that cause them to lose or fail to gain weight normally for at least one month, but was not caused by another medical or mental disorder.  Diagnoses of Feeding disorder of Infancy or Early Childhood were rarely made and poorly studied. They were also not applicable to patients over six years of age or to children under six who demonstrated food avoidance and restrictive food intake but who nonetheless were growing normally, perhaps due to nutritional supplements. 
In spite of its shortcomings, Feeding Disorder of Infancy or Early Childhood diagnosis identified patients with significant physical and psychosocial impairment. The DSM-5 Eating Disorder Working Group therefore sought to clarify and expand the diagnosis to encapsulate a greater number of patients with avoidant or restrictive eating who lack shape and weight concerns. ARFID is that new diagnosis. It better identifies the nature of the eating disturbances this subset of patients experience, and can be applied to patients of all ages. ARFID now exists as an eating disorder clinically distinct from Anorexia Nervosa and Bulimia Nervosa. The diagnostic criteria for it are defined in DSM5 as follows: 
An eating or feeding disturbance (e.g. apparent lack of interest in eating or food; avoidance based on the sensory characteristics of food; concern about aversive consequences of eating) as manifested by persistent failure to meet appropriate nutritional and/or energy needs associated with one (or more) of the following:
- Significant weight loss (or failure to achieve expected weight gain or faltering growth in children).
- Significant nutritional deficiency.
- Dependence on enteral feeding or oral nutritional supplements.
- Marked interference with psychosocial functioning.
- The disturbance is not better explained by lack of available food or by associated culturally sanctioned practice.
- The eating disturbance does not occur exclusively during the course of anorexia nervosa or bulimia nervosa, and there is no evidence of a disturbance in the way in which one’s body weight or shape is experienced.
- The eating disturbance is not attributable to a concurrent medical condition or not better explained by another mental disorder. When the eating disturbance occurs in the context of another condition or disorder, the severity of the eating disturbance exceeds that routinely associated with the condition or disorder and warrants additional clinical attention.
ARFID may arise from a variety of different social, psychological, and biologic factors, and further research is necessary to determine the exact nature of these contributions. Anecdotally, clinicians report that avoidance of eating may be rooted in traumatic experiences related to consuming food, such as a personal or witnessed episode of choking, gagging, or vomiting,  which may lead to food phobias that can persist into later years. Some patients report that they have restricted their diets since early childhood, that they experience recurrent gastrointestinal discomfort when they eat, or that they limit food intake because of unpleasant sensory experiences they have when confronted with food.  Other ARFID patients report a history of gastrointestinal conditions, gastroesophageal reflux disease, and vomiting that appears to have led to avoidance of food and restrictive eating. 
Selective or “picky” eating in childhood may also contribute to the development of ARFID. Although eating difficulties can be developmentally normal for infants and preschool children,  children with persistent restrictive eating patterns may be at risk for ARFID because early-onset restrictive eating is often accompanied by a higher risk of developing other eating disorders in the future.  However, further prospective and longitudinal studies are needed to clarify such a progression.
Although ARFID may first appear in adulthood or persist from childhood into adulthood, it usually presents in infancy or early childhood.  Individuals of any race, gender, or socioeconomic status may be affected. However, ARFID has been primarily identified and studied in the United States, Canada, Australia, and Europe.  American epidemiological studies of the incidence of ARFID in clinical samples have not been conclusive, reporting that between 13% and 29% of children and adolescents meet the criteria for ARFID upon initial presentation to eating disorder services.  A multicenter retrospective study of 8- to 18-year-olds presenting to adolescent eating disorder programs in 2010 reported a 14% incidence of ARFID,  while an extensive 11-year retrospective chart review of adolescent eating disorder patients in Canada discovered only a 5% incidence. 
ARFID not only appears to present at a younger age than Anorexia Nervosa or Bulimia Nervosa, but also affects a greater percentage of male patients than either of those disorders. [4, 9] In a retrospective case-controlled study of 712 adolescents presenting to eating disorder programs across the United States, Fisher et al. found that the average age of initial presentation for ARFID was 12.9 years, as opposed to 15.6 years for Anorexia Nervosa and 16.6 years for Bulimia Nervosa. In addition, nearly 30% of ARFID patients were male, more than double the proportion of male patients diagnosed with Anorexia Nervosa (14.3%) or Bulimia Nervosa (6%). Patients with ARFID also tended to have a longer duration of illness and presented with a median expected body weight percentage (86.5%) between those with Anorexia Nervosa (81%) and Bulimia Nervosa (107.5%).  Thus, from both a clinical and demographic standpoint, child and adolescent populations with ARFID are noticeably distinct from populations with Anorexia Nervosa or Bulimia Nervosa. Further research is needed to determine the demographic characterization and prevalence of ARFID in both non-clinical populations and in adult populations.
Long-term outcomes for patients with ARFID are not yet available. However, early detection of ARFID is presumably useful as in the case of Anorexia Nervosa and Bulimia Nervosa.