Constipation Beyond Fibre: Understanding Gut Motility and the Causes of Slow Transit
Written by Dr. Megan Woroch, ND
Naturopathic Doctor in Toronto, Ontario
Published: February 23, 2026 · Updated: October 18, 2026
You’re eating vegetables, drinking water and adding fibre, but you’re still struggling with constipation. Perhaps your bowel movements are infrequent, or you go regularly but still strain. More fibre may even make you feel more bloated.
Fibre can help, but persistent constipation deserves a closer look at how your digestive system works. Gut motility, pelvic floor coordination, medications and underlying health conditions can all influence bowel regularity.
What Is Gut Motility?
Gut motility refers to the coordinated muscle contractions that move food, and eventually stool, through your digestive tract.
When stool moves slowly, the colon has more time to absorb water. This can leave stool harder, drier and more difficult to pass. However, constipation can also happen when stool reaches the rectum, but the muscles involved in emptying can’t coordinate properly.
Peristalsis: How Your Gut Moves Its Contents
Peristalsis is the wave-like contraction and relaxation of muscles along your digestive tract (1). Muscles contract behind the contents and relax ahead of them, helping move food and waste forward. The enteric nervous system coordinates these movements, with input from the brain and other signals.
The colon also uses larger propulsive contractions to move stool towards the rectum. When these movements slow or become poorly coordinated, transit can slow. Fibre can improve stool consistency, but it cannot always correct the underlying motility problem.
The Migrating Motor Complex: Movement Between Meals
The migrating motor complex (MMC) produces repeated sweeping contractions in the stomach and small intestine between meals to help clear residual contents towards the colon (2). It is often described as the gut’s “housekeeping” system.
Eating switches the upper gut from this fasting pattern to contractions that mix and move a meal. Both patterns are normal and necessary. The MMC helps limit microbial accumulation in the small intestine, and impaired activity can contribute to susceptibility to SIBO (3).
However, the MMC is not the main mechanism that moves stool through the colon, and constipation alone does not mean it is impaired. Slow-transit constipation and small-intestinal motility problems involve different regions and may require different approaches.
Allowing natural breaks of ~3 hours between meals gives the digestive tract time to rest and the MMC to function.
Can You Be Constipated If You Go Every Day?
Yes. Constipation involves more than how often you have a bowel movement. Hard stools, straining and feeling incompletely emptied also matter.
No single number of bowel movements is ideal for everyone. A useful goal is a consistent pattern of comfortable, easy-to-pass stools, without significant straining or a persistent feeling that there is more to pass.
Why More Fibre Does Not Always Resolve Constipation
Fibre helps retain water and adds bulk to stool. Some types are also fermented by gut microbes, which can produce gas.
If your fibre intake is low, increasing it gradually may help. Psyllium has evidence for chronic constipation, although individual tolerance varies. However, adding more bulk does not necessarily correct slow movement or difficulty emptying.
If increasing fibre makes you more uncomfortable without improving bowel movements, reassess your approach. It does not automatically mean you need to avoid fibre, and it does not confirm slow transit.
A Transit Time test
One way to assess for constipation and retained stool is a transit time test. The most effective way to do this test at home is to eat ½ to 1 cup of whole corn kernels (limit excessive chewing and avoid laxatives). After you eat the corn, check your stools over the next few days and record when you first see it and when you stop seeing it.
Average transit times range from 30 to 40 hours, but optimal is closer to 12 to 24 hours.
What Can Contribute to Persistent Constipation?
Slow Colonic Transit
Slow-transit constipation means stool travels through the colon more slowly than expected. It can involve changes in the nerves and muscles that support colonic movement.
Infrequent bowel movements or a reduced urge to go may raise suspicion, but symptoms alone cannot confirm the diagnosis. A colonic transit study may be needed when constipation persists despite appropriate treatment.
Pelvic Floor Coordination
To pass stool, the pelvic floor and anal muscles need to relax while the abdomen generates gentle pressure (4). In dyssynergic defecation, these actions are not well coordinated.
Clues include excessive straining and feeling blocked or struggling to pass stool, even when it is soft. Pelvic floor dysfunction can also coexist with slow transit.
Treatment may involve pelvic floor physiotherapy and biofeedback to retrain coordination. The goal isn't simply to strengthen the muscles; learning to relax them appropriately is also important.
Gut Microbiome Changes, SIBO and Methane
Your gut microbiome and bowel motility are closely connected. People with constipation have shown changes in the composition and activity of gut microbes (5). However, the relationship can work both ways: slower transit can also change the microbial environment. Dysbiosis does not automatically explain constipation.
Small intestinal bacterial overgrowth (SIBO) can contribute to bloating, gas and altered bowel habits. Sluggish movement through the small intestine can also make it easier for microbes to accumulate, so addressing underlying motility issues may be an important part of care.
For constipation, the clearest microbial link is methane. Higher methane production is associated with slower intestinal transit, and experimental evidence suggests methane can slow movement (6). Although many call it “methane SIBO,” the more accurate term is intestinal methanogen overgrowth (IMO). Methane-producing organisms are archaea, rather than bacteria, and may be present in both the small and large intestine.
If constipation occurs alongside persistent bloating and gas, consider hydrogen and methane breath testing based on your history. These symptoms alone do not confirm SIBO or IMO, and breath tests have limitations. An individualized plan should address bowel function and any identified microbial overgrowth.
Medications, Supplements and Medical Conditions
Iron supplements, opioid pain medications, some antidepressants and certain blood pressure medications can contribute to constipation. Review when symptoms started in relation to a new product or dose change.
Hypothyroidism, diabetes, celiac disease and neurological conditions can also affect bowel function (7). Guide testing by your symptoms and history rather than ordering generic testing.
Eating Patterns and Daily Routines
Changes in food intake, hydration, activity and bathroom habits can affect regularity. Travel, rushed mornings, and repeatedly ignoring the urge to go may all contribute.
Meals also stimulate colonic activity through the gastrocolic reflex (8). Allowing time for the bathroom upon waking and after breakfast can help you work with that natural response.
The Gut–Brain Connection
Your gut and brain communicate continuously. In constipation-predominant IBS, changes in this communication can influence bowel habits and how strongly you experience discomfort.
Stress may worsen symptoms for some people, but persistent constipation should not be dismissed as stress alone. Nervous system support can be part of care while we assess other contributors.
How to Support Bowel Regularity Beyond Fibre
Start with a few consistent habits rather than adding several supplements at once:
Adjust fibre gradually. Choose foods and fibre supplements you tolerate, and monitor whether they improve stool consistency and ease of passing.
Stay adequately hydrated. Correcting dehydration helps; forcing excessive water is not a reliable treatment on its own.
Eat regularly and adequately. Review whether restrictive eating or changes in intake are contributing.
Make time after breakfast. Respond to the urge to go and avoid prolonged straining.
Move regularly. Walking and exercise can support your routine.
Track the whole picture. Record stool consistency, frequency and other digestive symptoms.
If these steps aren’t enough, additional treatment may be appropriate. Osmotic laxatives such as polyethylene glycol help retain water in stool. Some prescription treatments increase intestinal fluid, while others, such as prucalopride, support colonic movement.
Magnesium-based laxatives are another option in selected cases, but they are not appropriate for everyone, particularly people with impaired kidney function. Treatment should match the cause, your medical history and your response.
When Is Further Testing Helpful?
Persistent constipation despite treatment warrants reassessment. Depending on your symptoms, evaluation may include targeted blood work, a physical examination, anorectal manometry and a balloon expulsion test to assess emptying, or a colonic transit study.
A colonoscopy is not required for every case of constipation. It may be indicated for concerning symptoms or when colorectal cancer screening is due.
Seek medical assessment for rectal bleeding, unexplained weight loss or a persistent new change in bowel habits. Severe abdominal pain, vomiting or an inability to pass gas requires urgent assessment.
An Individualized Approach to Constipation
When I assess constipation, I want to understand more than how often you are going. Stool consistency, the urge to go, straining, medications, nutrition and other symptoms help guide the next steps.
If you are already eating fibre and drinking enough water, ongoing symptoms deserve further attention. Understanding whether the main issue involves stool consistency, movement through the colon or pelvic floor coordination helps us build a more appropriate plan.
As a naturopathic doctor in Toronto, I offer an individualized approach to digestive health. If constipation is affecting your comfort or daily life, book a visit to explore what may be contributing.
Dr. Megan Woroch, ND, is a Toronto-based naturopathic doctor with a focus on digestive health, immune and environmental health, and root-cause approaches to chronic health concerns. She uses evidence-informed naturopathic medicine, clinical nutrition, functional testing, and individualized supplementation to support her patients.
Learn more about a naturopathic approach to digestive health.
Disclaimer: This information is for educational purposes only and is not intended to provide or replace medical advice, diagnosis, or treatment. Always consult your qualified healthcare provider for individualized recommendations.