Eating Disorders and IBS – Are They Connected?

March 04, 2024

At The Alliance, one of our core missions is to provide education on topics surrounding eating disorders (EDs). We find that covering the nuanced issues that affect folks with eating disorders and their loved ones helps our community be more understanding, proactive, and resilient. Eating disorders are mental illnesses with severe physical side effects. Some of these side effects are related to gastrointestinal issues. One of the common GI issues that coexist with eating disorders is irritable bowel syndrome (IBS). Here, we go into the connections between these two conditions and take a look at some of the research on the relationship between eating disorders and IBS.

What Are Eating Disorders?

Before we examine the connections between eating disorders and gastrointestinal (GI) issues, let’s set the foundation. Eating disorders are highly stigmatized diseases; understanding these conditions is the first step to finding the right support. These mental illnesses have physical, mental, and emotional ramifications. Based on current research, the exact cause of eating disorders can’t be pinpointed as they arise from a complex interplay of genetic predispositions, social influences, and environmental factors. 

Types of Eating Disorders

Just as the causes of eating disorders are nuanced, the presentation of these illnesses are equally complex. Between our Learn page and the rest of our blog, we’ve got a wealth of resources to help understand the full picture of eating disorders, from signs and symptoms to treatments. But to help you understand the connections between EDs and IBS, here’s an overview of the five types of eating disorders as defined by the DSM-5 that we may mention. 

  • Anorexia Nervosa: Characterized by an intense fear of gaining weight, distorted body image, and restrictive eating, often leading to dangerously low body weight.
  • Bulimia Nervosa: Involves recurrent episodes of binge eating followed by purging behaviors such as self-induced vomiting, excessive exercise, or misuse of laxatives or diuretics to prevent weight gain.
  • Binge Eating Disorder: Marked by recurrent episodes of binge eating episodes without the compensatory behaviors seen in bulimia nervosa.
  • Avoidant/Restrictive Food Intake Disorder (ARFID): Formerly known as selective eating disorder, ARFID is characterized by an aversion to certain foods or a reluctance to eat, leading to malnutrition, significant weight loss, or failure to gain weight.
  • Other Specified Feeding or Eating Disorders (OSFED): Encompasses a range of disordered eating patterns that do not meet the criteria for the aforementioned disorders but still cause significant distress or impairment in functioning. This includes diagnoses of ED subtypes like “atypical” anorexia nervosa, low-frequency bulimia nervosa, or night eating syndrome.


Risks of Eating Disorders

While eating disorders primarily manifest as psychological illnesses, they often give rise to significant physical complications. EDs can affect blood pressure and circulation, bone density, heart function, and hormone levels. They often exist alongside other mental illnesses like anxiety, depression, or OCD and can sometimes lead to chronic health issues or even death. The side effects and dangers of eating disorders vary, but nearly all EDs can affect the functioning of the GI tract, leading us to the prevalence of IBS in eating disorder patients. 

What Is IBS?

Before we jump into more detail about the connection between EDs and IBS, let’s take a closer look at what IBS means. You’ve probably had a friend or family member complain of IBS, as awareness around the condition has risen in the last decade. Sometimes it may just be an off-handed mention of a flare up or they may request a certain diet to help alleviate their symptoms. But what exactly is irritable bowel syndrome (IBS)? 

Background on IBS

IBS is a type of functional gastrointestinal disorder that affects the digestive tract. Often, the function of the stomach and intestines is affected, resulting in cramping, gas, bloating, abdominal pain, and irregular bowel function. The condition is fairly common, affecting 10-15% of people in the United States. Though many cases go undiagnosed, IBS is one of the most common reasons patients are referred to a GI doctor. 

IBS is more commonly diagnosed in young people and women, though it can affect people in any demographic. People with IBS experience recurring stomach pain combined with either constipation, diarrhea, or a combination of irregular bowel movements. 

IBS and the Gut/Brain Connection

The causes of IBS aren’t fully understood. It doesn’t seem to be consistently linked to certain foods or behaviors, though both can be a factor. Currently, doctors believe IBS to be linked to the functioning of gut-brain interactions. The nervous system and the digestive system are integrally related through the gut-brain axis. Specifically, this involves the enteric nervous system, which comprises the group of neurons that control the movement and secretions of the GI tract. 

Though they seem like two unique systems, the gut and the brain can each affect the functioning of the other. Have you ever had the feeling of butterflies in your stomach when you’re nervous? Or had your appetite affected by grief? These are ways your nervous system impacts the functioning of your digestion. This process happens in reverse too. For example, the health of the gut microbiome has been related to mental illnesses like anxiety and depression.

To bring it back to IBS, doctors have seen connections between mental state and IBS symptoms. Feelings of stress, for instance, seem to exacerbate IBS symptoms by affecting the signals that regulate bowel function. In a similar vein to the effect of stressful life events, certain mental illnesses can potentially cause IBS. While food sensitivities may affect the prevalence of IBS for some people, these other factors demonstrate the relationship between the state of the nervous system and IBS. 

Understanding the interplay between mental health and gut health sets the stage for the relationship between IBS and eating disorders. By recognizing the physiological and psychological mechanisms underlying IBS, we can better appreciate how it intersects with the complex landscape of EDs. 


The Relationship Between Eating Disorders and IBS

As we mentioned above, eating disorders often cause issues with the GI tract, and IBS can stem from mental and emotional stressors. Needless to say, the two conditions are often intertwined. The relationship between eating disorders and IBS is pretty clear, though the precise pathways are nuanced. Furthermore, this connection seems to function in both directions, where individuals with IBS may be more prone to developing eating disorders in addition to the increased prevalence of IBS in eating disorder patients. Here, we take a closer look at some of the research that covers the breadth of these intersections. 

IBS Impact on The Development of Disordered Eating

First, let’s look at the impact of IBS on the potential development of eating disorders. A 2019 review linked the two, highlighting that people ongoing treatment for GI problems were more susceptible to developing disordered eating behaviors. Though IBS is influenced by mental stressors, the condition also shows some level of dietary responsiveness. This means that certain types of food may trigger symptom flare-ups. Because IBS can be exacerbated by eating certain foods, elimination diets may be a common treatment tactic. In many cases, a person may self-assign an elimination diet to try to mitigate their symptoms, but these treatments may also be prescribed by a doctor.

However, as we’ve seen with attempts for intentional weight loss, prescribed dieting can do more harm than good. Elimination diets can contribute to the development of eating disorders. In the case of IBS treatment, the symptoms can leave patients feeling like they have no control over how food impacts their bodies. They may adopt disordered eating behaviors to regain control or mitigate their fears around particular types of foods.

Eating Disorders Potentially Cause IBS

This relationship also works in the other direction, with eating disorders increasing the likelihood of someone developing IBS. Because of restricted food intake, purging behaviors, or other disordered eating patterns, eating disorders can cause gastrointestinal dysfunction. Malnourishment in the body can cause GI function to slow. Patients with anorexia nervosa and bulimia nervosa often experience delayed gastric emptying, meaning the food sits in the stomach for too long. This can cause nausea, abdominal pain, and bloating, along with other digestive issues. In one study on the connection of EDs and IBS, 64% of the participants with eating disorders also met the criteria for IBS. Furthermore, food restriction or malnutrition in eating disorders can disrupt the balance of beneficial gut bacteria, compromising the immune system and exacerbating IBS symptoms. Another review outlined the GI issues associated with different types of eating disorders. We’ve summed them up in the bullets below:

  • Anorexia Nervosa: Patients with AN often experience heartburn, regurgitation, bloating, reduced nutrient absorption, electrolyte abnormalities, and constipation as a result of limited food intake.
  • Bulimia Nervosa: In addition to many of the same consequences as patients with AN, those with bulimia nervosa may also experience spontaneous vomiting and nocturnal aspiration.
  • Binge Eating Disorder: Binge eating behaviors can cause heartburn and regurgitation due to reduced pressure on the esophageal sphincter. Additionally, people with BED may also experience bloating, diarrhea, and constipation, common symptoms of IBS.
  • ARFID: We mentioned some of the connections between IBS and ARFID above, but those with ARFID can also experience stomach pain, nausea, and constipation as a result of malnutrition.

Treating IBS and Eating Disorders Together

In conclusion, the relationship between Irritable Bowel Syndrome (IBS) and eating disorders demonstrates the interconnections between mental and physical health. Clinicians must recognize that these disorders frequently coexist, necessitating a nuanced approach to diagnosis and treatment for both conditions. Providers treating IBS should be on the lookout for potential signs of eating disorders like increased food restriction or a preoccupation with body shape or size. On the other hand, eating disorder treatment providers should be aware of all the physical symptoms of eating disorders, including IBS. 

Treating both conditions holistically can have a greater impact on positive patient care. At The Alliance, we can help connect people living with eating disorders (and their loved ones) with treatment providers and programs, as well as other support resources. For more information on how to get support, refer to our resources page or call our therapist-staffed helpline at 866-662-1235.