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  • Sara Geiger

Exploring the Gut-Brain Connection: Digestion and Disordered Eating

You likely clicked on this blog post because you have experienced some pesky digestive symptoms alongside disordered eating. Nausea, vomiting, indigestion, constipation, diarrhea, early fullness, and the list goes on. Two of the most common questions from clients in the early stages of recovery are, “When will insert GI symptom here go away?” and “Is this normal?!” We are here to provide you with evidence-based info to navigate these questions while you heal from your eating disorder.

If you're wondering if and when these symptoms will improve, the answer is that it depends on many factors.

Some questions to consider are:

  • How long have you been struggling with an eating disorder or disordered eating?

  • Did you have any pre-existing digestive issues?

  • Do you limit your intake to foods that you would describe as “whole” or “clean”?

  • Are there any food allergies or intolerances you’re aware of?

  • Where does anxiety show up for you and your body?

  • Do you take a probiotic daily?

  • How fast or slow do you typically eat?

  • And so many more.

When it comes to these issues, one thing is clear:

Disordered eating & digestive issues are like two evil villains who spend every moment together. 

When there’s disordered eating, there’s likely digestive trouble following suit. A study from the Journal of Neurogastrointestinal Motility discovered that up to 98% of those with an eating disorder also have a functional disorder. A functional gut disorder includes things like IBS, constipation, diarrhea, and bloating that are otherwise not showing up on other medical examinations. Regardless, these symptoms are persistent and real to the individuals who experience them. Beyond disordered eating and eating disorders, studies correlate several mental health disorders, like anxiety, depression, and autism spectrum disorders with gastrointestinal-related distress.

The connection between digestive issues and disordered eating can be thought of as a "chicken or the egg" dilemma. Maybe you had digestive issues first, and as a result of the symptoms and changes to eating you made, your relationship with food suffered. Or maybe you had an eating disorder and that negatively impacted your digestion. Understanding how these issues intersect, and addressing both, is so important for complete healing.

To better understand why it is so common to struggle with digestive issues when experiencing disordered eating, let's explore the gut-brain connection.

According to the Integrative Medicine Journal, the gut-brain axis is a “bidirectional communication network that links the enteric and central nervous systems.” In other words, your gut and brain are constantly chatting back and forth. You have probably felt this communication first-hand. Phenomena like “butterflies in your stomach” or that “stomach sinking” feeling when something shocking occurs are examples of the gut-brain axis in action. 

Let's look at some ways that disordered eating and digestion connect.

When you are in fight or flight mode, so is your digestive system!

In a moment of panic, your body's first instinct is not the perfect harmony of all systems- it’s survival! Your body desperately wants to maintain homeostasis and stay alive, even when you are deep in the trenches of an eating disorder. Major organs, like your heart, brain, and lungs, will be prioritized before digestion as they are more critical for survival. They'll receive blood flow and resources that the body also needs for optimal digestion.

In chaos and stress, your sympathetic nervous system kicks into gear to activate “fight or flight." Anxiety can keep us in “fight or flight” consistently mentally, leaving us feeling those digestive effects physically. On the other hand, your parasympathetic nervous system regulates the “rest and digest” period in the body. When you're resting and relaxed, your body has energy and resources to repair and digest. Engaging the parasympathetic-driven rest and digest system is crucial for a regular bathroom schedule, and we know this can be challenging when food and body image are a major source of stress.

Eating patterns can change your experience with digestion

Like any muscle, your gastrointestinal smooth muscle can become weak without typical use. It is no surprise that the word “gastroparesis” quite literally means a partial paralysis of the stomach. Your digestion may become so delayed, the muscles so weak, that you experience early fullness, bloating, and constipation. In addition, digestion is complicated and requires a lot of energy to work efficiently. When your body doesn’t get enough energy, it adapts to survive. It’s not uncommon for someone with an eating disorder to have a slow heart rate or blood pressure dysregulation as the body lowers its metabolic rate. This applies to digestion as well. Digestion is complicated and requires a lot of energy to work efficiently. A range of organs and enzymes and hormones are involved, all of which require energy to work, so this can slow down.

In general, eating enough food and eating consistently helps promote regular digestion. Once you start eating more adequately, the body will take some time to adjust. It has to relearn how to digest food efficiently so it can feel like a bumpy road at first as your body remembers what to do and has more resources to do it effectively.

95% of our total body serotonin is sourced from our gastrointestinal tract, AKA the gut

Serotonin is a neurotransmitter that actively regulates our mood and increases feelings of happiness. It only makes sense that any disruption to our digestive system can impact our mood. When we are eating in a disordered manner, we are not providing our body with adequate nourishment OR happy chemicals! 

The food (or lack of food) you eat influences the gut microbiome

Not only can the pattern and amount we eat affect our digestion and mood, the types of food we eat can change the bacteria within our large intestine. These bacteria feed on prebiotics which in turn fuels them to help ferment and break down food into feces. Pretty cool, right?

This means that restriction of our intake and a lack of balance in our diet can present a challenge for our microbiome.

The sensational idea of a “reset” or “cleanse” can sound extremely appealing when you are feeling nauseous and bloated all the time, desperately seeking answers. However, this often causes more damage as elimination diets often further reduce the amount and variety of food you eat. Not to mention it can lead to constant thoughts about which foods you “can” and “can’t” have. Hello, food noise and stress, which we already established makes digestion even worse! We can give our body the energy it needs, our brain the serotonin it wants, and microbiome the diversity it requires without sacrificing our gut health. Your long-term health requires a sustainable, curious, and holistic approach to behavior change, rather than a quick band-aid fix.

Like the gut-brain axis, your relationship with food may feel complicated. If you’re struggling with this, please reach out to learn how we can work together! We have a great deal of experience supporting clients as they navigate eating disorder recovery and uncomfortable digestive issues. You can contact us here to connect and schedule an appointment.


  1. Appleton J. (2018). The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integrative medicine (Encinitas, Cfbyalif.), 17(4), 28–32.

  2. Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Frontiers in psychiatry, 9, 44.

  3. Janssen P. (2010). Can eating disorders cause functional gastrointestinal disorders?. Neurogastroenterology and motility, 22(12), 1267–1269.

  4. Seitz, J., Trinh, S., & Herpertz-Dahlmann, B. (2019). The Microbiome and Eating Disorders. The Psychiatric clinics of North America, 42(1), 93–103.

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