Lauren Gerber, Equip’s Head of Brand & Comms, says she always considered herself to be a fairly obsessive person. But she never identified as someone with obsessive-compulsive disorder (OCD), a mental illness characterized by uncontrollable and recurring thoughts (obsessions), repetitive behaviors (compulsions), or both. She was also never formally diagnosed with the condition—until 15 years after she’d recovered from her eating disorder. Her story is unique, but far from rare, as the overlap between OCD and eating disorders is bigger than many people realize.

“Looking back, I believe OCD absolutely helped fan the flame for my eating disorder,” Gerber says. “I remember not being particularly mentally interested in food or my body or dieting during my eating disorder. I was instead absolutely fixated on the number on my scale—specifically it being an even, flat number—or a precise ratio of certain ingredients. I know this now to be indicative of 'symmetry' or 'perfectionism' OCD, but for years, I just thought I had a strange version of an eating disorder and the rigidity that came with it.”

What is obsessive-compulsive disorder (OCD)?

Obsessive-compulsive disorder, as the name implies, is a mental illness that’s characterized by uncontrollable obsessions and compulsions. According to the DSM-V, obsessions are defined as “recurrent and persistent thoughts, urges, or images that are experienced, at some time during the disturbance, as intrusive, unwanted, and that in most individuals cause marked anxiety or distress.” These obsessions go hand-in-hand with compulsions, which is when a person with OCD attempts to ignore, suppress, or neutralize an obsession by performing a certain action or thinking a certain thought.

While the hallmark symptoms of OCD are these obsessive thoughts and the compulsive behaviors meant to manage them, this can manifest in a number of different ways.

While some people may have obsessions that revolve around germs or contamination (with accompanying compulsions like excessive handwashing, for example), others may obsess over fear of losing control, which could be accompanied by a compulsion like calorie counting or intense food monitoring. OCD presents differently from person to person, but research suggests that the illness may be classified into several broad categories, including:

• Checking, in which the person engages in safety checking compulsions
• Indecisiveness, in which the person becomes obsessed with making the correct decision
• Contamination, in which the person’s obsessions are related to both realistic and unrealistic contagions or contaminations
• Just right, in which the person has uncomfortable feelings that things are not “just right” (symmetry and order falls under this category)

How are OCD and eating disorders connected?

Eating disorders are complex, multifaceted brain disorders rooted in biological, psychological, and social risk factors and triggers. For some people with eating disorders, obsessive thoughts around food, weight, or body size may lead to levels of anxiety that can only be quelled by compulsive behaviors, like restriction, purging, over-exercise, and more. In these ways, the symptoms of certain eating disorders can look almost identical to the symptoms of OCD.

“There is a high rate of comorbidity between eating disorders and OCD,” says Equip’s Director of Program Development, Tana Luo, PhD. She explains that while prevalence estimates tend to vary widely, lifetime prevalence of OCD in people with eating disorders has been found to be as high as 60%, and lifetime prevalence of an eating disorder in people with OCD is as high as 17%.

While some studies indicate that rates of OCD are higher in those with anorexia than in those with bulimia, Luo says other research indicates no difference from diagnosis to diagnosis, particularly when looking at lifetime prevalence.

“There can be many similarities in how OCD and eating disorders present,” Luo says. “For example, both OCD and eating disorders may be characterized by obsessive, distressing thoughts. For those with an eating disorder, those thoughts tend to center on things like weight, food, and body image, whereas for those with OCD, the content of the thoughts may focus on things like contamination and harm, among many other things.”

Eating disorders and OCD tend to share other common characteristics as well, like repetitive or compulsive behaviors. “For those with an eating disorder, the behaviors may include ritualistic eating behaviors, exercising, or purging,” Luo says. “And for those with OCD, there’s a range of compulsive behaviors that may be present. In both cases, the compulsive behaviors function to reduce a person’s fear and anxiety.”

OCD that focuses on symmetry and order can also contribute to an eating disorder, as this type of OCD involves obsessions over numbers and counting. In someone predisposed to an eating disorder, this can manifest as a fixation on weight, body measurements, calories, or other food- or body-related numbers.

Does OCD cause eating disorders—or vice versa?

As with most mental health conditions, neither OCD nor eating disorders have a single or straightforward cause. Both illnesses can result from a multilayered interaction of family history, environment, biology, and more. Because of these complicated roots, neither condition is thought to “cause” the other—but the symptoms of both can occur simultaneously, or one diagnosis may follow the other.

Some researchers suggest that certain personality traits and cognitive styles may increase vulnerability to both OCD and eating disorders, which Luo says may explain why there’s such an overlap between the two. “Perfectionism, for example, is one trait that has been found to be associated with both eating disorders and OCD,” Luo says. “Perfectionism refers to the drive to meet a high standard, being highly critical of oneself, and experiencing significant distress in response to perceived failure. This trait may make a person more vulnerable to developing both an eating disorder and OCD.”

Additionally, Luo points out that eating disorders and OCD are both marked by cognitive inflexibility and challenges with set-shifting, the ability to move back and forward between different tasks or mental sets. “These cognitive styles may increase susceptibility to both disorders,” she explains.

While OCD and eating disorders can co-occur, Luo says it’s not uncommon for people with eating disorders to demonstrate obsessive-compulsive behaviors in the absence of true clinical OCD. “That is, someone who is struggling with an eating disorder may have many distressing obsessions about food, weight, and their body, and they may engage in ritualistic or compulsive eating-related behaviors,” she says. “But if all of those symptoms are occurring exclusively within the context of the eating disorder, the person wouldn’t meet criteria for OCD, too.”

Even though obsessions and compulsions around food or weight may not merit an OCD diagnosis if those behaviors are all associated with an eating disorder, it’s important to note that low weight and malnutrition can actually increase obsessive-compulsive symptoms. This triggers what Luo calls a “vicious cycle” that starts with disordered eating behaviors leading to weight loss. “Then that weight loss increases the person’s cognitive rigidity, which leads them to engage in more disordered and compulsive eating behaviors, which leads to further weight loss, and so on and so forth,” she says.

This doesn’t mean that OCD causes eating disorders, but rather indicates how the former might come before the latter in a person who is genetically vulnerable to both disorders. In order to properly diagnose and treat people, Luo says it’s critical for providers to assess the nature and timeline of the onset of obsessive-compulsive behaviors, as well as those of the eating disorder and any weight loss. “That way, providers can determine whether the patient truly has a comorbid eating disorder and OCD or if the obsessive-compulsive symptoms are occurring only in the context of the eating disorder,” she says.

How treatment addresses eating disorders and OCD concurrently

Just as eating disorder treatment requires a multidisciplinary approach, OCD may also require various forms of therapy, medications, or both to address and manage symptoms. Because there’s so much variability within these illnesses, there isn’t necessarily a one-size-fits-all treatment to tackle both, and expert-led, individualized care is typically recommended.

“There isn’t strong evidence to support the use of just one treatment modality for both diagnoses,” Luo says. “Cognitive behavioral therapy (CBT) principles can be effective for both, although the specific applications will vary. More specifically, cognitive behavioral therapy for eating disorders (CBT-E) is an evidence-based treatment for eating disorders, and exposure and response prevention (ERP), which is a type of CBT, is the gold standard for OCD.”

The absence of one standard treatment protocol to address both disorders at once doesn’t mean that they can’t be treated effectively at the same time. While Luo explains that CBT and ERP share the same underlying principles and thus work well together, other treatment modalities can also be successful in treating OCD and eating disorders together. “Even if a treatment other than CBT is being used to treat the eating disorder—say, family-based therapy (FBT)—it’s still possible to introduce ERP alongside that treatment,” shes says. “In any case, people struggling with both an eating disorder and OCD should work closely with a treatment provider to determine the best way to treat both disorders and the timeline for treating each.”