Eating disorders are complex mental health conditions involving serious disturbances in eating behaviors, thoughts, and emotions. Professional diagnosis is necessary to distinguish these conditions. Since both Anorexia Nervosa (AN) and Avoidant/Restrictive Food Intake Disorder (ARFID) involve food restriction, people often wonder if a person can have both diagnoses simultaneously.
Defining Anorexia Nervosa
Anorexia Nervosa is characterized by restricting energy intake relative to requirements, resulting in a significantly low body weight. This low weight is defined relative to the person’s age, sex, and developmental trajectory. This sustained restriction is a core diagnostic component.
The defining psychological feature of AN is an intense fear of gaining weight or becoming fat, or persistent behavior that actively interferes with weight gain, even at a significantly low weight. This fear drives the restrictive behaviors.
A further criterion involves a disturbance in the way one’s body weight or shape is experienced, known as body image disturbance. This can manifest as an undue influence of body shape and weight on self-evaluation, or a persistent lack of recognition regarding the seriousness of the current low body weight. This intense, body-image-related motivation separates AN from other causes of low weight.
Defining Avoidant/Restrictive Food Intake Disorder (ARFID)
ARFID is characterized by an eating disturbance that results in a persistent failure to meet appropriate nutritional and energy needs. This disturbance can manifest in several ways:
- Significant weight loss or failure to achieve expected growth.
- Nutritional deficiency.
- Dependence on nutritional supplements.
- Marked interference with psychosocial functioning.
Unlike other eating disorders, ARFID does not require the individual to be underweight.
The restriction in ARFID is not driven by the psychological components of Anorexia Nervosa, meaning there is no fear of gaining weight or body image disturbance. Instead, the restrictive behavior is associated with three primary drivers.
Primary Drivers of ARFID
One driver is a lack of interest in eating or food, often presenting as low appetite. Another common driver is avoidance based on the sensory characteristics of food, such as texture, smell, or temperature. This sensory sensitivity can lead to a highly limited repertoire of “safe” foods. The third driver involves concern about aversive consequences from eating, such as a fear of choking, vomiting, or experiencing pain. These non-body-image-related motivations distinguish ARFID as a separate diagnosis.
The Diagnostic Rule: Simultaneous Diagnosis
The criteria for both disorders confirm that an individual cannot have both ARFID and Anorexia Nervosa simultaneously. The formal diagnostic rule states that the eating disturbance cannot occur exclusively during the course of Anorexia Nervosa, and there must be no evidence of body weight or shape disturbance. The two disorders are considered mutually exclusive.
If a person restricts food leading to low weight and expresses an intense fear of fatness or shows body image disturbance, the diagnosis of Anorexia Nervosa takes precedence. The presence of body image concerns excludes an ARFID diagnosis. This exclusionary rule exists because the underlying psychological motivation for the restriction is the primary factor used to differentiate the two conditions.
The ARFID diagnosis is reserved for those whose restriction is caused by sensory issues, fear of adverse consequences, or low appetite, and not by a desire for thinness. If a patient meets the full criteria for AN, they cannot also be diagnosed with ARFID.
Distinguishing Factors in Differential Diagnosis
The clinical challenge is distinguishing between an underweight ARFID patient and an AN patient, as the physical effects of malnourishment are often identical. The primary differentiating factor is the patient’s internal experience and motivation. Clinicians must conduct a detailed interview to determine the reason why the individual is restricting food.
Patients with AN consistently report a desire to be thin and a fear of weight gain, often expressing dissatisfaction with their body shape. ARFID patients do not express these body image concerns, instead focusing on the sensory properties of food or a specific fear, like vomiting.
The types of foods avoided also offer a clue. AN patients typically avoid foods based on caloric or fat content, such as high-energy dense items. ARFID patients often avoid entire categories of foods based on texture, which can lead to a restricted diet that includes highly processed, low-nutrient foods if they meet sensory criteria.
The patient’s reaction to weight restoration is another distinguishing factor. ARFID patients generally welcome weight restoration as a necessary medical step to resolve physical symptoms. Conversely, individuals with AN approach weight restoration with significant anxiety and resistance because it challenges their core fear of gaining weight. This difference in attitude helps clinicians apply the exclusionary rule for accurate diagnosis and effective treatment planning.