Orthorexia nervosa and anorexia nervosa are eating disorders that can share symptoms like restrictive eating, preoccupation with food, and rigid dietary practices, but what sets them apart are the underlying behaviors and attitudes about eating.

Eating disorders (EDs) involve long-term eating behaviors that negatively affect your physical health and psychosocial (psychological and social) function. They are mental health disorders linked to distressing thoughts and emotions.

Anorexia nervosa (AN) and orthorexia nervosa (ON) are EDs that can feature overlapping symptoms. Despite their similarities, however, they involve different underlying attitudes about food.

Orthorexia (ON) and anorexia (AN) are distinct conditions defined by different preoccupations with food.

With AN, disordered eating behaviors center around fears of being overweight or gaining weight. AN is about calorie and food quantity restriction. In ON, disordered eating behaviors arise from an obsession with healthy eating. Instead of quantity, your focus is on the quality of food.

Both thought processes can cause avoidance of certain foods, rigid and ritualistic eating habits, and nutritional deficits.

However, the diagnosis you receive will depend on more than just food attitudes. AN features intense fear about weight gain and a distorted body image perception.

According to 2023 research, ON does not involve intense fears about body shape and weight, though weight control can still be a priority when you live with ON.

For a diagnosis of AN based on criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR), your body weight must be significantly low for what’s typical for your age, sex, developmental trajectory, and physical health.

ON isn’t yet recognized in the DSM-5-TR, but weight is not considered a marker of this eating disorder. Many people living with ON remain at or around a healthy weight for them.

Orthorexia symptoms

Symptoms of ON may include:

  • obsession with food quality and nutritional content
  • rigid diet habits focused on “clean” eating
  • avoidance and intolerance of foods perceived as unhealthy
  • social withdrawal from food-related events
  • excessive time spent purchasing and preparing food
  • decreased social, occupational, academic, or personal function

Anorexia symptoms

AN symptoms include:

  • severe calorie restriction
  • intense fear of weight gain or of being overweight
  • lack of recognition about the seriousness of low weight
  • distorted body image
  • binging/purging behaviors
  • excessive exercise
  • decreased social, occupation, academic, or personal function
  • physical health effects like brittle nails and irregular menstrual cycles

A serious complication of AN is organ failure.

Attitudes toward your food and related behaviors are what differentiate ON and AN. While you can’t diagnose yourself, you may be able to determine if your symptoms are more aligned with one or the other.

Examples of what ON may look like:

  • spending excessive amounts of time researching and selecting the “right” food item
  • avoiding ingredients or entire food groups perceived as unhealthy
  • refusing to cook food a certain way because it might cause illness
  • feeling anxious about making an unhealthy food choice
  • punishing yourself if you eat something outside of your self-imposed diet
  • always talking and thinking about food quality, purity, and nutritional content
  • skipping meals if someone else cooks because of the unknown quality of food items
  • habitual use of cleanse diets or fasting

Signs you may be living with AN include:

  • having an extreme fear of weight gain or being overweight
  • restricting of all types of foods, not just those considered unhealthy
  • thinking that you’re overweight no matter what you do or what others say
  • misusing products like laxatives and diet pills to ensure you don’t gain weight
  • dismissing others’ concerns that you may be underweight
  • not believing that being underweight is unhealthy

No standardized diagnostic criteria currently exist for ON, making it challenging to define all possible symptoms and experiences.

Proposed diagnostic symptoms cited in a scientific paper from 2017 include:

Criterion A: Obsessive focus on healthy eating accompanied by excessive emotional distress about food choices perceived as unhealthy. Weight loss is not a primary goal but may be a natural consequence. Supporting symptoms include:

  • preoccupation with, or compulsive behavior about, restrictive dietary practices thought to promote optimal health
  • extreme fear of disease, a sense of impurity, or negative sensations if self-imposed dietary rules are broken
  • a sense of anxiety or shame about eating something perceived as unhealthy
  • dietary restrictions that become more limiting over time, often leading to weight loss

Criterion B: The disordered eating behaviors become clinically impairing (i.e., leads to consequences). Supporting symptoms include:

  • malnutrition
  • severe weight loss
  • medical complications from restricted diet
  • distressed state of mind
  • impaired social, occupational, and academic function
  • positive body image and self-worth are intricately linked with self-defined healthy eating behaviors

Anorexia nervosa criteria

The DSM-5-TR defines AN by the presence of:

  • energy restriction to less than you need, leading to significantly low body weight or failure to meet developmental body weight expectations (specifically in children)
  • intense fear of being overweight or of gaining weight that prevents any healthy weight gain
  • a distorted body image and persistent lack of recognition about the seriousness of current low body weight
  • self-worth influenced by body weight or shape

When AN behaviors are primarily related to dieting, limiting food, and excessively exercising, “restricting type AN” is diagnosed. Behaviors that include binging or purging, like inappropriate use of laxatives, lead to a diagnosis of “binge-eating/purging type AN.”

The lack of standard diagnostic criteria makes it difficult to know the prevalence and effect of ON. A literature review from 2021 estimates it may affect anywhere from 7–89%, depending on the country.

More is known about AN. It’s more common in females than males, but prevalence across all gender identities is unknown. Teen girls between the ages of 13 years and 19 years, as well as women in their early 20s, have the highest risk.

Immediate treatment for eating disorders involves improving your physical health. You may need a brief stay in a care facility if serious health concerns, like organ failure, are present.

As you build your physical health, psychotherapy can help address the underlying causes of disordered eating.

Both ON and AN are treated using psychotherapies, like cognitive behavioral therapy (CBT), that help you identify and restructure unhelpful thoughts and behaviors about eating.

According to 2023 research, mindfulness and acceptance-based treatments may also be beneficial for people living with ON. These approaches can help you detach from food-related distress while learning to identify underlying emotions.

Orthorexia nervosa (ON) and anorexia nervosa (AN) are both eating disorders (EDs). They’re differentiated by underlying food attitudes and behaviors even though they can share some overlapping symptoms.

ON is about food quality, while AN is about food quantity. However, ON is not yet recognized in the DSM-5-TR.

Like other EDs, ON and AN can cause physical and psychosocial impairment. Psychotherapy, particularly CBT, may help treat both conditions.