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Slowed metabolism, which happens when the body is consistently getting less energy (i.e. calories) than it needs, also slows digestion and can cause the aforementioned constipation, bloating, and gastroparesis. When your body isn’t getting enough food, it will prioritize other bodily functions that are more essential to survival, like breathing or oxygenating the body, with less energy going towards digestion.
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As you might imagine, someone with an eating disorder can experience pretty intense anxiety at mealtime. That anxiety has multiple effects on the digestive tract, including increasing gastric pressure (instead of lowering pressure, which usually happens when we eat) and pushing blood flow to the extremities instead of the gut. As I remind clients, the opposite of the fight or flight part of your nervous system (i.e. sympathetic) is the rest and digest (i.e. parasympathetic) nervous system!
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Eating limited food variety can disrupt the gut’s microbiota. A healthy, diverse gut microbiota thrives off of a diverse diet. When you cut a food group out of your diet, you also cut out a food group for the bacteria in your gut.
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Excessive fiber consumption, from eating too many vegetables, fruits, whole grains, and beans (i.e. what basically every health influencer tells you to do) can cause extreme gas and bloating. Yes, there is such thing as too much fiber!
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Self-induced vomiting weakens the esophageal sphincter, leading to gastric reflux (GERD). Technically, gastric reflux is not IBS, but the two are connected because GERD, and some treatments for it, can impact digestion further along in the gut.
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Use of laxatives can lead to weakening of the gut muscles, over time reducing function of the smooth muscle of the colon. Over time, one’s gut learns to rely on laxatives for a bowel movement.
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Chaotic eating patterns, especially the restrict-binge cycle typically seen in bulimia and binge eating disorder, can contribute to symptoms. Imagine what it’s like to be your gut, getting no stimulation from food for long periods of time, then all of a sudden a much larger quantity than you like to digest at once!
How IBS can fuel an eating disorder
Research suggests it’s more common for someone to develop IBS after an eating disorder, but many people develop an eating disorder or disordered eating as a result of trying to manage their IBS symptoms through diet. In my practice, I typically see this present as orthorexia.
IBS can lead to an eating disorder in a variety of ways. First, experiencing distressing GI symptoms after eating primes the nervous system to be activated at meal time. Essentially, if you regularly experience symptoms soon after eating, especially if you’re not sure what will or won’t trigger symptoms, of course you’ll feel anxious every time you eat! As one of my clients with IBS once described it to me, “it’s like I’m playing Russian roulette every time I eat.” You can imagine how that amount of mealtime anxiety could impact one’s relationship with food!
Another factor at play is the prevalence of restrictive diet advice for managing IBS. When you’re told the key to managing symptoms is an ever-expanding list of what not to eat, and the symptoms you’re experiencing are taking a huge toll on your quality of life, it makes sense that you’d try to cut certain things out. For people with anxiety (who tend to be predisposed to both eating disorders and IBS) adding something back in can feel terrifying, even when cutting a food out doesn’t help.
Speaking of anxiety, it’s important to note that it may not be a simple story of “IBS caused the ED” or visa versa. There are other factors that can increase risk or cause both IBS and an eating disorder, including anxiety, trauma, genetics, and sensory processing issues.
Tips for Managing an Eating Disorder and IBS
If you struggle with an eating disorder and IBS, here’s some tips that may be helpful:
Be wary of elimination diets.
Elimination diets are appealing, but they can do a lot more harm than good if you’re not in a good place with food. Frankly, they can do more harm than good even if you’re in a good place with food! Before eliminating any food or attempting an elimination diet, I’d encourage you to make sure you’re working wIth a dietitian who has experience with IBS and disordered eating if it’s accessible. We’re always happy to help, or can connect you with someone in your area!. Working with a dietitian can help you manage your symptoms in the least restrictive way possible. It might sound counterintuitive, but often adding food is more effective than subtracting!
Focus on adequacy, consistency, and balance first.
In my practice, “adequacy first” is practically a mantra. When it comes to helping our clients address their nutrition and health concerns, our first priority is to make sure they are fueling their body adequately. There’s a reason it’s the base of my hierarchy of nutrition needs! Because undernutrition is such a major factor in IBS, before starting any other nutrition intervention or supplement, we help our clients aim to eat regularly throughout the day (usually 3 meals and at least 2 snacks) with a combination of fat, protein, and carbs. Nutrition rehabilitation treats the IBS symptoms that are related to disordered eating patterns and renourishes the gut. As the body heals, we can see what symptoms remain and target those with medication, supplements, lifestyle, or dietary intervention.
Low calorie foods and methods of appetite suppression may contribute to symptoms.
Many people with an eating disorder will attempt to fill up their stomach with the least number of calories, or engage in behaviors to suppress appetite in an attempt to manage their weight. Eating large volumes of airy, low calorie foods (think popcorn or rice cakes), excessively chewing gum, or drinking large amounts of carbonated beverages can cause you to swallow a lot of air, which can cause reflux, bloating, and stomach pain. Many sugar free foods are made with sugar alcohols, which can cause diarrhea and bloating. Same goes for fiber enriched foods (I’m looking at you fart bars – I mean fiber bars!) which use a fiber called inulin that the bacteria in your gut looove to ferment. Coffee is another drink frequently used as an appetite suppressant, but the caffeine can trigger urgency and cramping.
Destress before meals.
When you have an eating disorder, meal and snack times are understandably stressful. Unfortunately, the gut is not a fan of stress, so learning strategies to turn the stress down a notch before eating can be helpful. Try a 2-5 minute guided meditation, stretching, or deep breathing exercise, like diaphragmatic breathing or box breathing. I also love to recommend progressive muscle relaxation, as it helps target the tension that’s often held in the gut.
