On the surface, obsessive-compulsive disorder (OCD) and eating disorders might not seem like they have much in common. But both involve distressing thoughts and emotions that can drive repetitive or specific behaviors.
Eating disorders involve various forms of eating pattern disturbances driven by negative thoughts and emotions. This category includes conditions such as anorexia nervosa, binge eating disorder, and bulimia nervosa.
Obsessive-compulsive disorder (OCD) is a mental health condition that involves intrusive thoughts (obsessions) and mental or physical acts used to neutralize emotional distress (compulsions).
Both OCD and eating disorders can feature repetitive thoughts followed by specific behaviors, and these conditions often co-occur. When OCD and eating disorders happen at the same time, they’re considered “comorbid” conditions.
OCD and eating disorders commonly co-occur. The relationship has long been established in research and in diagnostic manuals such as the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR).
According to the DSM-5-TR (the clinical guidebook used by mental health professionals in the United States), rates of OCD are higher among people with certain mental health conditions, including eating disorders.
A 2020 research review found that globally, 15% of people who have an eating disorder have OCD at the same time, and 18% of people with an eating disorder experience OCD at some point in their lives (even if the two conditions do not happen at the same time).
Earlier research suggests the comorbidity rate may be even higher, with as many as 41% of people with eating disorders also experiencing OCD and 17% of people with OCD also experiencing eating disorders.
Which eating disorder is most commonly associated with OCD?
According to the 2020 review mentioned above and a 2021 review, anorexia nervosa is the eating disorder that most commonly occurs alongside OCD. The authors of the 2021 review note that the chance of OCD is highest in anorexia nervosa binge-eating purging type.
Health experts do not fully understand the reason for the high rate of co-occurrence of OCD and eating disorders.
Other theories focus on innate traits, such as neuroticism, that may increase a person’s likelihood of experiencing comorbid OCD and an eating disorder.
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Overall psychological state may also influence how frequently — and when — OCD and eating disorders occur together.
A large-scale 2022 study suggested that people with co-occurring OCD and eating disorders may have a subcategory of OCD with more severe mental health effects, specifically related to trauma and symptoms of anxiety and depression.
The relationship with eating challenges isn’t always an eating disorder
The relationship between OCD and eating challenges is complex, no matter how you look at it. While OCD can co-occur with an eating disorder, OCD may also involve compulsions related to eating, food, or exercise without the presence of an eating disorder.
For example, an obsession related to germs may cause you to avoid certain foods or eating situations due to anxiety about unsanitary conditions. This can look like a symptom of an eating disorder when it’s actually an OCD contamination compulsion.
The DSM-5-TR states that OCD differs from an eating disorder when obsessions and compulsions are not strictly limited to concerns about weight and food. In other words, OCD encompasses a wider range of intrusive thoughts and behaviors, while eating disorders center on fixations with food and weight.
But the theme behind distressing thoughts and emotions isn’t the only difference. The nature of the intrusive thoughts also separates these conditions.
Ego-dystonic vs. ego-syntonic
In OCD, intrusive thoughts are typically ego-dystonic, meaning they are in direct conflict with your self-identity or value system. For example, if you innately believe hurting people is wrong, your obsessions in OCD may involve thoughts about causing harm to others.
In eating disorders, intrusive thoughts are typically ego-syntonic, meaning they’re aligned with your current beliefs. You may believe you should weigh a certain amount, for example, so you experience distressing thoughts and emotions about meeting those expectations.
Relevance of body perception
Body image distortion can also set eating disorders apart from OCD when considered with other diagnostic factors. While it’s possible to have low self-esteem and body image concerns in OCD, body image distortion — a misperception of how you look — is a part of the DSM-5-TR diagnostic criteria for eating disorders such as anorexia nervosa.
Rigidity of behaviors
In OCD, compulsions typically follow a rigid, self-imposed set of rules. When you experience an obsession, you perform compulsions in the same way every time, often because failing to do so leaves you feeling incomplete or does not relieve your anxiety.
Repetitive behaviors can also be part of eating disorders, but rigidity is not considered a necessary or significant feature for diagnosis.
As with their symptoms, OCD and eating disorders have some overlapping treatments, including psychotherapy and medication, but with notable differences.
Cognitive behavioral therapy (CBT) is a therapeutic approach that can be used in both OCD and eating disorders but with individual targeted approaches.
In OCD, exposure and response prevention (ERP) therapy is considered the gold standard CBT option. The goal of ERP is to gradually expose you to circumstances that trigger intrusive thoughts in a controlled atmosphere while providing you the tools you need to not engage with compulsions.
In eating disorders, CBT is still the gold standard, but a different CBT-based therapy called dialectical behavioral therapy (DBT) may be used. DBT takes the essence of CBT — identifying and restructuring distorted or unhelpful thoughts — and adds components such as mindfulness and acceptance to help address emotional and interpersonal challenges.
Eating disorders are also treated with interpersonal therapy and family therapy to address other challenges that may contribute to distorted body perception and low self-esteem.
Treatment for both OCD and eating disorders can involve medications to manage symptoms such as anxiety and depression, but antidepressants may be used in OCD for additional neurotransmitter benefits aside from mood regulation.
OCD and eating disorders commonly co-occur and have some common features, including intrusive thoughts that lead to specific behaviors.
Despite their similarities, OCD and eating disorders are separate diagnoses. OCD encompasses a broader range of intrusive thoughts and behaviors that do not align with your inner value system.
Eating disorder thoughts, while distressing, are typically in step with your individual values. And while they can lead to repetitive behaviors, those behaviors don’t necessarily follow a rigid rule set like those in OCD.
Both OCD and eating disorders can be treated using CBT-based psychotherapy approaches and medication.