The information in this article originally appeared in an Equip Academy presentation. Watch the presentation here, and register for future Equip Academy events to learn about other eating disorder-related topics and earn free CE credits.

Often, people with eating disorders have another co-occurring mental health condition. One common co-occurring diagnosis is obsessive-compulsive disorder (OCD). In this article, we’ll explore what providers should know about identifying, differentiating, and addressing these two conditions in patients. Read on to learn the shared risk factors for both OCD and eating disorders, how to tell the two apart, and considerations for sequencing treatment for a patient with both diagnoses.

Prevalence of OCD and eating disorders

Why do we so often link these two disorders? Well, one reason is because eating disorders and anxiety disorders, like OCD, commonly co-occur.

The overall prevalence of OCD in the United States for both children and adults is 0.5%-1%, with an average age of onset around 10 to 12 years old, or in late teens/early adulthood (which mirrors the average age of onset for eating disorders). Among eating disorder patients, between 16-69% have a co-occurring anxiety disorder, and for 41% of this group, it’s OCD. One recent review found that lifetime prevalence of OCD for eating disorder patients is 38%; on the other side, an estimated 11% of OCD patients also report having clinically significant eating disorder symptoms. It’s also worth noting that anxiety disorders precede eating disorders in 50-60% of cases.

While disordered eating symptoms may not be more elevated generally in OCD patients, there is a higher risk for having clinically significant eating disorder symptoms in female OCD patients: 9% among female OCD patients vs 1% among the control group. According to a meta analysis, there are no differences in the prevalence of OCD among the different eating disorder diagnoses; there is some evidence that symptoms of OCD may be higher among those with anorexia than those with bulimia, but that could be due to the fact that low weight can exacerbate obsessive-compulsive symptoms.

Similarities between OCD and eating disorders

In many ways, it makes sense that OCD and eating disorders have significant overlap, because the two disorders have many similarities:

• Both OCD and eating disorders involve distressing, intrusive thoughts.
• Both OCD and eating disorders involve behaviors that function to alleviate distress associated with intrusive thoughts.
• Both OCD and eating disorders can involve thought-action-fusion (TAF), or the idea that obsessional thoughts can influence the actual outcome of events.
• People with eating disorders and OCD share similar personality traits.
• There is a high genetic correlation between anorexia and OCD (though genes linked to metabolism and weight loss are distinct to eating disorders)

So are they the same disorder? Different? Are eating disorders a type of OCD? One way to answer these questions is through network analysis. Network analysis is a way of studying the causal role of symptoms in activating and maintaining psychological disorders. Symptoms that are more central—or more strongly connected—play a larger role in activating a disorder. When comparing the networks between two disorders, it’s important to look for symptoms that are strongly connected and that co-occur between both diagnoses.

The most common shared symptoms between the two disorders are symmetry, checking, and ordering, and the most common shared personality traits are perfectionism, neuroticism, conscientiousness, and impulsivity. Both disorders also involve concern over mistakes and difficulty controlling thoughts. While one network analysis found no connection between the two disorders, another found that perfectionism and difficulty controlling thoughts both bridge the two disorders.

There appears to be a synergistic relationship between OCD and eating disorders. Research supports that the presence of OCD in a person with an eating disorder increases the severity of the eating disorder and leads to a worse prognosis—which is all the more reason to detect and adequately treat OCD in someone with an eating disorder.

Differentiating between OCD and eating disorders

So, how do you know if your eating disorder patient has OCD? And how can you differentiate between OCD and an eating disorder, and vice versa?

To effectively make this distinction, it’s important to understand how OCD is diagnosed. For someone to be diagnosed with OCD, they must meet the following criteria:

• Presence of obsessions, compulsions, or both
• The obsessions and compulsions are time-consuming, or cause clinically significant distress or impairment in social, occupational, or other areas of functioning
• The obsessions and compulsions aren’t related to substance use or another medical condition
• The obsessions and compulsions aren’t better explained by the symptoms of another disorder (like an eating disorder)

There are several screening tools that providers can use to assess for OCD. Two options are:

Obsessive Compulsive Inventory Revised (OCI-R)

• Widely available, brief screening instrument to assess for OCD
• Adult and child versions
• Available in multiple languages, including Spanish
• Clinical cutoffs available for adults and children

Yale-Brown Obsessive Compulsive Scale (Y-BOCS and CY-BOCS)

• Semi-structured diagnostic interview, freely available
• Can be administered to ages 6+; children may be interviewed with parent or separately
• Provides a full symptom checklist and severity ratings for determining impairment

Remember that it’s always a good idea to ask patients about OCD symptoms, rather than waiting for them to bring them up. Often people are too embarrassed or ashamed by their obsessions to admit them freely.

There are a few questions to ask when considering whether a patient has OCD or if the obsessive-compulsive symptoms stem from the eating disorder. Providers should think about:

1. Timing: Are obsessive-compulsive symptoms exclusive to a period of extreme weight loss? Do they abate with weight gain?

2. Beyond food and weight: Are there obsessions or compulsions outside of the realm of food or weight? To what extent will treatment focus on eating?

3. Egosyntonic or dystonic: The body image disturbance seen in anorexia is egosyntonic (meaning it aligns with a person’s values or self-image). It is a perceptual disturbance, not just body dissatisfaction.

Case examples

To better understand how co-occurring OCD and eating disorders might present, it can be helpful to look at some case examples.

Case example 1: a Black, teenage girl obsessively cleans every part of her body to the point of causing her skin to bleed and crack to prevent catching Covid while hospitalized for acute weight loss and anorexia.

Case example 2: a White man in his early 20’s fears that his food has expired and will make him sick. He obsessively checks expiration dates and inspects food for signs of spoilage before eating it and avoids eating out at restaurants.

Case example 3: An adult woman with body image concerns meticulously cleans all surfaces, including wiping down her food before eating it because she fears absorbing fats. She wears gloves when out in public to avoid touching things.

Integrated care for OCD and eating disorders

When treating co-occurring OCD and eating disorders in patients, integrated care is essential. Using an integrated care approach reduces the burden on patients and removes barriers to accessing treatment. Being able to treat multiple disorders at the same location or with a single provider/team of providers is not only an efficient use of resources, it’s also best for patients.

There are a number of different evidence-based treatment approaches for OCD. These include:

Cognitive-behavioral therapy with exposure and response prevention (ERP): First-line treatment that involves facing fears imaginally or in real life while preventing compulsions.

Pharmacotherapy (serotonergic agents): First-line treatment using SSRIs including fluoxetine, sertraline, fluvoxamine, paroxetine, and escitalopram. Research has linked genes involved in coding serotonin to OCD.

Combination therapy: Psychiatric medication in combination with exposure and response prevention therapy can also offer a good option.

Treating OCD and eating disorders together

There are a few different potential options for treatment of OCD and an eating disorder. The conditions can be treated in sequence, simultaneously, or you can just treat one.

Option 1: Sequence the treatments. Treat the most impairing or “primary” diagnosis first.

Option 2: Treat the conditions simultaneously. Alternate sessions, integrate treatment together, or split sessions.

Exposure is a common thread woven through both eating disorder and OCD treatment. The particular exposures will be different for each condition and vary from person to person. For those with OCD, they may be exposed to fears and prevented from engaging in compulsions. Common exposures in eating disorder treatment involve exposure to fear foods, to challenging eating environments (like restaurants), or to challenging behaviors (for instance, not exercising).

In one naturalistic study of 56 patients with both OCD and eating disorders in a residential facility, researchers found that treating both issues concurrently resulted in improvements in both OCD and eating disorder symptoms, and weight restoration.

Some important tenets of treating both OCD and eating disorders include:

Weight gain: Standard meal plans and supervised eating. Low body weight or weight suppression exacerbates obsession and compulsion symptoms, and may interfere with learning.

Exposure and response prevention (ERP): ERP for OCD symptoms delivered in three-hour blocks daily. Consider the patient’s ability to tolerate distress during exposure so that eating disorder behaviors are not used to cope with increased anxiety.

Eating fears: Eating fears are addressed in a manner consistent with ERP.

Key takeaways about OCD and eating disorders

Here are the important things providers should remember about OCD and eating disorders:

• OCD and eating disorders commonly co-occur. People with all eating disorders are at particularly heightened risk of developing OCD.
• While OCD and eating disorders are distinct and separate conditions, they share many features, including personality traits and cognitive styles/features.
• When both disorders are present, an activation of symptoms in one disorder can worsen or activate symptoms of the other disorder.
• Cognitive behavioral therapy with exposure and response prevention and SSRIs are the first-line treatments for OCD.
• There is a small amount of evidence that simultaneous treatment of eating disorders and OCD can be effective; exposure is a common element of treatments for both disorders.
• The amount of body weight lost, the need to restore weight, and the patient’s ability to tolerate distress are all important considerations in the decision to start ERP during eating disorder treatment.

For more information on the intersection between OCD and eating disorders and how to treat both, watch my recorded Equip Academy presentation on the topic. You can also explore past Equip Academy presentations and register for upcoming events here.