Fiber, Gut Health and Eating Disorders

Bowel habits, pooping, bloating, distention, gas, and more!

GI distress can be a tough subject - understandably so. Attention on it is important since alleviating GI symptoms can make a positive difference in mood, recovery from disordered eating and overall wellbeing.

Many people, including those with disordered eating patterns, suffer from GI distress.

GI distress can occur due to disorders of Gut-Brain Interaction (DGBI) like functional dyspepsia, functional diarrhea and Irritable Bowel Syndrome (IBS), as well as Inflammatory Bowel Disease like Crohns, bile acid diarrhea, Small Intestinal Bacterial Overgrowth (SIBO) and so much more.

It is really important for everyone with gut distress to have a thorough assessment followed by treatment and support for the challenges.

It is always important to talk to a doctor if you are having GI symptoms and red flags like blood in the stool, unexplained weight loss or a significant change in bowel habits.

Since fiber is such an important part of gut health and can be a tool in managing DGBIs and other conditions that cause gut distress, we will discuss it today.

In this article, I’ll get into what fiber is, what types can be helpful for which symptoms and how to think about fiber’s role in the diet especially in recovery from dysfunctional eating.

What is fiber?

Fiber is a non-digestible carbohydrate that is found in many foods including whole grains, vegetables, fruits and nuts/seeds.

It is very important to our health for a variety of reasons, including:

• The growth of beneficial bacteria in the gut

• The formation of short chain fatty acids, which may lower proinflammatory cytokines and have been shown to play a role in colon cancer prevention, among other benefits (Liu, et al, 2024)

• Softening and firming stools

• Promoting gut motility and regularity, faster gut transit time

• Lowering cholesterol

• Positively impacting blood sugar

• Association with decreased risk for type 2 diabetes, heart disease and diverticulitis

Fiber is characterized by its gel-forming ability, or viscosity, fermentability and solubility.

• Viscosity is the ability of fiber to thicken when it is wet and form a gel-like consistency.

• Fermentability is how much the fiber can be broken down by bacteria in the gut, giving off carbon dioxide and other gases, which draws water into the gut and can have somewhat of a laxative effect.

• Solubility describes fiber’s ability to dissolve in water or not.

There is a wonderful table of fibers available on pages 66-67 of the EDGI Training Project Workbook.

Recommended amounts of fiber across different country’s guidelines is around 25-30 grams per day.

What is soluble fiber?

Soluble fiber is found in chia seeds, oatmeal, pears, apricots, oranges, potatoes without the skin, butternut squash, peeled cucumbers, mushrooms, zucchini and more.

Think about soluble fiber as the inside of an apple.

Soluble fiber absorbs water into the gut. It becomes spongy and somewhat gummy in digestion.

Soluble fiber can help with diarrhea and constipation because it slows down transit and bulks up and softens stool, putting pressure on colon walls and allowing for more regular stools.

Soluble fiber can be gel-forming, fermentable and also contain prebiotics. Prebiotics feed the beneficial bacteria (or probiotics) in our gut.

Having 5-10 grams of soluble fiber per day is typically recommended.

What is insoluble fiber?

Insoluble fiber is found in foods like leafy greens, celery, corn kernels, lentils, peas, grapes, dried fruit and more.

Think about insoluble fiber like the skin of the apple.

It is found in the skins and seeds of fruit and the outer bran of a whole grain. It goes through your GI system undigested and so it acts as a cleaner of sorts.

Insoluble fiber speeds up gut transit time and while it does not absorb water itself, does pull water into the colon. Too much insoluble fiber, as we’ll discuss below, can actually slow things down.

Insoluble fiber does not create a gel-like structure and is usually poorly fermented.

Challenges with Fiber and Gut Health: Common Observations

In my work, I have observed a few patterns when it comes to fiber intake and its intersection with eating.

Here are a three examples:

Issue #1: Eating too much insoluble fiber and not enough soluble fiber.

Who? Folks dealing with restrictive eating patterns and those with orthorexia or more rigid thoughts of what is ‘healthy’ can struggle with this.

Sometimes, people who are just trying to eat healthier also find themselves in this situation.

How it looks: People are often eating a lot of roughage- basically, insoluble fiber in the form of salads, raw fruits and veg, whole nuts/seeds and beans/lentils.

GI Challenges: Individuals can develop constipation. They can become full of stool, which then can have effects described in the next section.

Possible Interventions: A potentially helpful intervention is increasing soluble fiber, whether in a supplement or food form (food is ideal if intake is inadequate), and decreasing insoluble fiber. Other ideas are to:

• Changing the consistency of the food so it is soft and easy to digest like cooked veggies versus a salad or peanut butter instead of peanuts

• Eat more adequately overall

• Eat at regular intervals throughout the day to help the gut move regularly, supporting motility

Issue # 2: Not eating enough fiber.

Who? Clients with Avoidant and Restrictive Food Intake Disorder, restrictive eating, on GLP-1s, older adults, folks with IBS and those struggling with bulimia or binge eating can struggle with this.

How it looks: Someone may not have many safe foods that have fiber or not have much of an appetite and so not eating enough fiber or enough overall. If someone is binge eating, they may overeat on lower fiber foods and then restrict due to the guilt and aftermath of a binge, not getting in enough fiber overall.

GI challenges: Not getting enough fiber can lead to a whole host of GI symptoms including constipation (which again to lead to folks being full of stool!), appetite dysregulation, higher risk for hemorrhoids, bloating and more. Of course, there are also potential negative side effects on the microbiome, heart disease risk, diabetes/blood sugar management, cancer risks, and more (Ioniță-Mîndrican, et al. 2022).

Possible Interventions: Typically, folks benefit from increasing overall food intake, working to have enough safe foods and calories first, and considering increasing a balance of soluble and insoluble fiber through food as appropriate. For instance, if someone has limited food options with ARFID and is working on experimenting with more, it may mean working from apple sauce up to a slice of apple.

Supplemental forms of fiber and perhaps a bowel regimen that includes fiber are often helpful in this population while food intake is being worked on.

Issue #3: Clients eating too much fiber overall.

Who? This can happen when someone is struggling with orthorexia and trying to eat so healthy that they end up not getting enough of the other foods we need in our diet. Or, someone may be restricting their food and ‘filling up’ on fibrous foods to keep them from feeling hungry.

How it looks: Most of the time, someone is eating too little calories and too much total fiber is being consumed.

GI challenges: Too much fiber can cause constipation, abdominal cramping, pain, bloating and gas. It can be even more problematic if someone is struggling with gastroparesis (slowed stomach emptying), SIBO or functional dyspepsia (when the stomach is very sensitive to gastric contents and can cause pain and discomfort after eating).

Possible Interventions: Discussing what is truly an adequate and balanced diet and decreasing the fiber while increasing other foods that are needed to increase the macronutrients or micronutrients they are missing out on often helps.

It is also important to attend to the GI symptoms and monitor them as fiber intake is lessened to see if they improve or if other interventions are needed. Sometimes increasing dietary fat can be a wonder for constipation!

Chronic Constipation is Real and Under-recognized!

In my experience, many clients with eating disorders who have GI distress struggle with some form of chronic constipation.

Chronic constipation can cause a stool burden, where stool backs up in the colon. This back up then can cause bloating, distention, pain and even nausea and reflux if the stool burden is big enough.

I see this quite frequently. A stool burden can be easily seen on a KUB x-ray or may even present as not having ‘fully cleaned’ out before a colonoscopy.

Unfortunately, co-occurring SIBO, gastroparesis and pelvic floor dyssynergia are outcomes that are not uncommon in the ED population and they need to be addressed for someone to also work on the ED in tandem.

A Note on Fiber Supplements

Fiber supplements can be helpful for people who are struggling with DGBI or gut distress.

Fiber supplements include polycarbophil (Fibercon), psyllium husk (Metamucil), methylcellulose (Citrucel), guar gum and more.

It is important to discuss your fiber needs with a dietitian or other medical professional who is versed in this area. There is quite a bit of nuance. While Citrucel, for instance, may help those with IBS-D or chronic diarrhea, it may be constipating for other people.

Closing Thoughts:

Gut health is really important and working on managing symptoms can be very helpful for anyone, including those working on recovery.

Getting enough of a variety of fiber is important for gut health, and it can also be difficult if you’re struggling with disordered eating or other considerations that impact food intake.

When thinking about fiber intake, it is important to consider your symptoms, your diet, your stress levels, your diagnoses and decide together how to improve fiber intake, meal timing, portioning/eating enough and more as they all work together to impact our gut. Many people benefit from increasing soluble fiber in their diets.

It is possible for your gut to feel better and to eat adequately and nourish yourself!

References

Arkin, et al. Comprehensive Nutrition Therapy for Co-Occurring Gastrointestinal and Eating Disorders. Gatekeeper Press, 2024. https://www.edgitraining.com/

Hanel V, Schalla MA, Stengel A. Irritable bowel syndrome and functional dyspepsia in patients with eating disorders - a systematic review. Eur Eat Disord Rev. 2021 Sep;29(5):692-719. doi: 10.1002/erv.2847. Epub 2021 Jun 4. PMID: 34086385.

Ioniță-Mîndrican CB, Ziani K, Mititelu M, Oprea E, Neacșu SM, Moroșan E, Dumitrescu DE, Roșca AC, Drăgănescu D, Negrei C. Therapeutic Benefits and Dietary Restrictions of Fiber Intake: A State of the Art Review. Nutrients. 2022 Jun 26;14(13):2641. doi: 10.3390/nu14132641. PMID: 35807822; PMCID: PMC9268622.

Liu G, Tang J, Zhou J, Dong M. Short-chain fatty acids play a positive role in colorectal cancer. Discov Oncol. 2024 Sep 10;15(1):425. doi: 10.1007/s12672-024-01313-5. PMID: 39256239; PMCID: PMC11387572.

McKeown NM, Fahey GC Jr, Slavin J, van der Kamp JW. Fibre intake for optimal health: how can healthcare professionals support people to reach dietary recommendations? BMJ. 2022 Jul 20;378:e054370. doi: 10.1136/bmj-2020-054370. PMID: 35858693; PMCID: PMC9298262.

Oshima, T., & Miwa, H. (2015). Epidemiology of functional gastrointestinal disorders in Japan and in the world. Journal of Neurogastroenterology and Motility, 21