Top 21 Causes Behind Chronic Constipation, IBS, Enlarged Hemorrhoids, and Diverticular Disease

Constipation starts as a nuisance: a missed day here, a bit of bloating there. By the time bowel movements require straining, they become noticeable — a little pain down there, 10 minutes on the toilet instead of 2 or 3, a feeling of incomplete emptying, a lump under the anus, an occasional drop of blood on a toiler paper, a first laxative... These seemingly minor initial issues are the beginning of far more serious disorders later on.

Most obvious among them are bloating, flatulence, abdominal cramps (especially during the period), hard stools, incomplete emptying, irritable bowel syndrome, occasional diarrhea, enlarged hemorrhoids, rectal fissures, diverticular disease, and some others.

The development of these conditions is a gradual process caused by the pressure on the colon and rectum from straining needed to expel large, hard, or dry stools. As these issues accumulate, they are worsened even more by fiber-rich diets and fiber laxatives that require even more straining.

The hardships with chronic constipation have recently become especially acute for millions of people taking the GLP-1 weight loss medicines. According to clinical studies, it affects up to 35% of patients taking these drugs, and it is also one of the longest-lasting side effects, averaging up to 46 weeks. If you are in this group, this article is a must-read.

I'll walk you through the top 21 causes behind chronic constipation. These root conditions set this entire cascade in motion—something I've observed again and again over years of research, writings, and while helping clients. Some are dietary, some behavioral, and the majority are iatrogenic—a fancy word for well-meaning but harmful advice by medical professionals.

While reading this article, you may come across several repetitions that describe similar conditions in different contexts. They are intentional because some readers may only search for specific causes, so repeating key information for another context is essential.

Whether you're managing chronic symptoms or trying to prevent the next flare-up, this guide will help you identify what's driving chronic constipation and related side effects, one cause at a time. Before you can fix the end of the chain, it's best to understand how it starts. Let's begin!

Diet and State of Health

The first group of constipation causes is related to your diet and state of health and includes dependence on a high-fiber diet, colon dilation, reduction or loss of urge sensation, and large stools:

1. Dependence on a high-fiber diet

Excess dietary fiber increases stool size, volume, and weight. In turn, large stools alter the anatomy, sensitivity, and tonus of the colon, rectum, and anus. The attachment to fiber rears its ugly head when fiber-containing products, all of them carbohydrate-heavy, are reduced during weight loss diets (with or without GLP-1 drugs), the colon remains dilated, and you run into the next problem on my list.

2. Colon dilation

Years of holding in large stools, partially driven by high-fiber diets, suppressed urges, or both, stretch the walls of the colon. In worse cases, this condition may turn into an acute, chronic, or toxic megacolon.

The colon’s dilation reduces the effectiveness of contractions needed to move along stools. Contact with the mucosal wall is necessary to trigger peristaltic propulsion. Loss of mechanical contact reduces propulsion, weakens the effectiveness of the defecation reflex, leads to ineffective transit, and results in incomplete evacuation.

3. Reduction or loss of urge sensation

When bulky or retained stools repeatedly dilate the rectum, the sensory nerves adapt and become less responsive. This adaptation is a natural protective mechanism, just like when your skin becomes less sensitive to pressure or heat after repeated exposure.

But in the case of the rectum, it works against you. Over time, the urge to defecate weakens or disappears entirely, even when the rectum is full. Without this critical signal, bowel movements become delayed, inconsistent, or entirely absent until the stool load becomes too large or too painful to ignore.

4. Large stools, even when consuming a small amount of food

Yes, this sounds paradoxical, but actually it isn’t. This condition develops gradually and is an outcome of incomplete bowel emptying related to any other number of factors on this list. As a result, newly formed stools pile up on top of the old ones, then compress and enlarge.

Since each consecutive bowel movement is incomplete, the stools close to the exit become larger, harder, and even more difficult to expel because of pain and discomfort while straining.

Muscular Dysfunction and Withholding Habits

The second group of constipation causes is related to muscular dysfunctions and withholding habits and includes stool withholding, excessive flatulence, hypertonic anal sphincter, and pelvic floor dyssynergia. They are quite common, take time to develop, are definitely not in your head, and are easier to prevent than reverse:

5. Conscious suppression of bowel movements

People routinely ignore and suppress defecation urges because of inconvenience, time constraints, lack of access to bathrooms, poor sanitary conditions, and embarrassment factors of using public bathrooms. Suppressing the urge retrains the rectum to delay evacuation, gradually weakens the defecation reflex, and leads to muscular dysfunctions.

6. Excessive flatulence

This condition isn’t a problem while you are alone, but a real menace when not. To retain gases, people tighten their anal and pelvic muscles just like during bowel movement withdrawal, and they gradually cause the muscular dysfunctions described above.

7. Hypertonic anal sphincter

This condition is common in people who routinely practice bowel movement withdrawals by tightening anal and pelvic muscles. When this is done for long enough, the muscles begin to enlarge and tighten up very similarly to the biceps and glutes in bodybuilders, but at a much smaller scale. And, by the way, this issue also affects bodybuilders who practice weighted sit-ups (i.e., sit-ups with dumbbells on shoulders).

8. Pelvic floor dyssynergia

This clinical term refers to a condition where the pelvic floor muscles contract instead of relaxing during an attempted bowel movement, making stool passage difficult or impossible. The primary cause of this condition is a fear of pain during bowel movements related to enlarged hemorrhoids and lacerations of the anal canal.

9. Anal intercourse

Anus and rectum are not designed for penetration and lack the protective adaptations of the vaginal canal. As a result, the anal sphincters — both voluntary (external) and involuntary (internal) may lose their natural tonus and reflex control.

Chronic stretching and trauma can also reduce sensory sensitivity and impair the reflexes that initiate and coordinate bowel movements. In more advanced cases, this loss of muscular tone and nerve signaling may result not only in constipation but also in episodes of fecal incontinence.

In addition to muscular and neurological compromise, repeated penetration may contribute to structural changes such as microtears, scar tissue formation, and inflammation of the rectal lining.

Fear of Pain While Moving Bowels 

10. The fear of pain during defecation is caused by different conditions that result from most other causes on my list. It leads people to delay bowel movements or terminate them prematurely. These conditions make constipation worse, creating a vicious cycle of incomplete evacuation and worsening inflammation. 

The primary sources of pain are straining to expel large stools; hard and dry stools regardless of their size; burning, irritation, or soreness from the bouts of diarrhea; itching, bleeding, and swelling related to enlarged hemorrhoids; sharp, cutting pain from anal fissures; and different infections and skin conditions that may be exceptionally painful in that highly innervated region.

Disrupted Bowel Physiology

Тhe fourth group of constipation causes is related to disrupted bowel physiology and includes laxative dependence and delayed gastric emptying:

11. Dependence on laxatives and laxogenic foods

Chronic use of laxative medications and “natural” laxogenic foods like prunes, aloe, or senna disrupts normal peristalsis, reduces urge sensation, and leads to dependency. Over time, the bowel becomes less responsive to natural signals and increasingly reliant on external stimulation to initiate defecation. In many cases, people believe they are using safe or gentle remedies, unaware that they are slowly training their bodies to stop functioning on their own. When a weight-loss diet comes along, the prior doses no longer work for all other reasons described in this list.

12. Delayed gastric emptying (gastroparesis)

Delayed stomach emptying slows the passage of food from the stomach to the small intestine and leads to persistent fullness, bloating, nausea, gastric reflux, malabsorption of nutrients, dehydration, and many other complications.  

As a result, the stomach stays stretched out with food and fluids for longer periods. The semi-permanent distention disrupts the stimulation of the vagus nerve, gastrocolic reflex, and peristaltic mass movements that normally precede and initiate natural bowel movements.

Dietary and Electrolyte Deficiencies

The fifth group of constipation causes is related to dietary and electrolyte deficiencies and includes table salt deficiency, weight loss diets, and low intake of fat:

13. Table salt deficiency

Low-salt diets reduce chloride levels needed to synthesize neurotransmitters and maintain the integrity of the blood, lymph, interstitial (between the cells), intracellular fluids, stomach acidity, and fluid balance in the intestines.

The ions of chloride come from sodium chloride — the chemical name for table salt. Without enough sodium chloride in the diet, the colon reabsorbs all the water it can from the stool to recover it, leaving stools dry and compacted.

Dry, small, hard, pebble-like stools are symptomatic of this condition. They are very painful to pass, even when there are no other causes for constipation. The resulting pain and trauma initiate the chain of constipation pathologies described throughout this list.

14. Weight loss diets

Weight-loss diets of any kind reduce food volume and, indirectly, the volume of bulking agents, such as natural and added fiber in morning cereals, pasta, and specialty breads.

Without the fiber, stool size becomes smaller, and the urge to defecate weakens for reasons described in other sections of this list. Smaller stools may not make full contact with the walls of a dilated colon, which is needed to propel them forward and initiate defecation.

While the rectum can still register smaller stools, this reflex may be blunted in individuals with diminished sensitivity caused by nerve damage, adaptation, or overstretching — the conditions commonly associated with chronic constipation. In this context, even normal peristalsis becomes less effective, and bowel movements become irregular or incomplete.

So, when you hear that “you may have slow motility,” it is not true because there is no “speed” control in the stomach or intestines that you can control.

The last time around, a drug called Propulsid (cisapride) had tried to speed up gastric motility, but instead, it disrupted heart rhythm, killed a lot of people, and was removed from the market in 2000. So don’t fall for this ‘slow motility’ trope.

There are exceptions related to systemic drugs that affect the smooth intestinal muscles governing peristalsis, and I’ll address them later.

15. Low-fat intake

One of the more persistent nutrition myths is that dietary fat slows digestion. In reality, it does the opposite. Fats play a central role in regulating appetite and motility by stimulating the release of hormones that activate the gastrocolic reflex — the signal from the stomach to the colon that initiates the urge to move the bowels. Without that signal, bowel movements may become infrequent or incomplete, especially when total food volume is also reduced.

16. Reduced volume of food in the meal

The urge to move the bowels is initiated in the stomach following the stretching of the stomach walls with incoming food and fluids. This mechanical stretch triggers the gastrocolic reflex — a powerful neural signal that travels from the stomach to the colon, prompting peristaltic contractions and generating the urge to defecate. When the diet drastically reduces the volume of food and fluids, the stomach doesn’t stretch sufficiently, and the reflex is either weakened or absent.

Without adequate food volume to stimulate the reflex, bowel movements become irregular or delayed, even if stool consistency and colon function are otherwise normal. In many cases, restoring normal bowel rhythm requires nothing more than restoring enough food and fluid volume to activate the reflex properly.

Exercise or Any Other Strenuous Activities

17. The sixth group of constipation causes is related to physical exercises that can be characterized as intense. They aren’t particularly common among weight loss dieters, but I must mention them here because they are commonly encouraged.

I am not anti-sport. Despite my ‘academic’ appearance, I’ve been quite physical all my life and still am. Also, over the years, I’ve had an opportunity to advise several world-class athletes who had access to the top medical experts but still couldn’t resolve the digestive disorders that nearly ended their careers. I mention this not to impress you but to prepare you for what comes next.

One of the most common and damaging constipation-related recommendations is to strengthen your abdominal and pelvic muscles under the mistaken belief that they’re essential for defecation. They're not. These are skeletal muscles, and their only real contribution is to help you strain, something I’ve already described as the equivalent of a wrecking ball.

The forces that actually move stool are the involuntary smooth muscles that line the intestinal walls. You can’t train them at the gym, no matter how hard you try.

There are at least a dozen other ways intense exercise can worsen constipation and digestive disorders. I’ll get to those in future segments.

And, yes, I am absolutely for moderate exercises at any age because they are critical for all aspects of your physical and mental health that drive all other aspects of your personal and professional lives.

Systemic Influences

The seventh and final group of constipation causes on my list is related to systemic factors and includes stress, personality type, medicines, and preexisting medical conditions:

18. Stress

Weight loss efforts often come with anxiety, calorie counting, body image, and financial stress. Collectively, these factors stimulate a voluminous secretion of stress hormones that disrupt digestion, inhibit gastrointestinal motility, and exacerbate some or all of the above conditions even more.

19. Personality type

Constipation is often reinforced by factors that go beyond the ones I already described. High levels of stress and anxiety are well-known contributors, but so are certain personality types, particularly those prone to perfectionism, control, or chronic tension, which affect muscle tone and bowel habits.

20. Systemic medicines

Medications such as opioids, antidepressants, antacids, and iron supplements frequently suppress motility or alter stool consistency. Drug abuse, especially involving stimulants, sedatives, or painkillers, can profoundly disrupt neurological and muscular control of defecation.

21. Preexisting medical conditions

Underlying medical conditions — including hypothyroidism, diabetes, neurological disorders, and connective tissue diseases — may impair colorectal function either directly or through their treatments.

Taken together, these systemic factors can act alone or magnify preexisting issues, creating a treatment-resistant form of constipation that requires individualized evaluation beyond what can be accomplished with functional means and lifestyle changes.

Conclusion and Takeaways

This overview completes my list of the primary causes of chronic constipation, and it’s far from complete because it addresses mainly functional (i.e., diet- and lifestyle-related) causes. The remaining clinical causes are too technical for this format and require the assistance of a GI physician, which I am not.

Here are the top seven takeaways from my list:

1. Constipation isn’t a trivial or “in your head” condition, as many doctors claim, but a serious and debilitating disorder that is both preventable and, in most early cases, reversible.

2. Don’t teach young children, especially girls, to withhold stools when the bathroom is available, even if it isn’t up to your sanitary standards. Once you train them to cross their legs and skip the urge, they’re set for a lifetime of trouble.

3. Constipation is the first tangible condition in the long chain of colorectal disorders, starting with bloating and flatulence and, for the less fortunate, ending with colorectal cancers preceded by inflammatory bowel disease, a euphemism for Crohn’s disease and ulcerative colitis.

4. If most of these causes sound new to you, you're not alone. The Merck Manual of Diagnoses and Therapy, Professional Edition — the most widely used medical reference in the world — devotes just 2,600 words to “Constipation.” That’s shorter than this introduction and reflects how little medical professionals know about constipation [link].

5. The default recommendations to eat more fiber, drink more water, and exercise more will make constipation worse. Fiber enlarges the stool, excessive water dilutes electrolytes needed to maintain stool moisture, and stronger abdominal muscles encourage straining.

6. Weight loss diets with or without GLP-1 drugs exacerbate constipation because of drastically reduced food volume, medication side effects, and preexisting colorectal disorders. Starting a weight loss program with a prior history of constipation is a near certain guarantee of developing severe colorectal disorders during the process.

7. Finally, the longer constipation persists, the more it rewires your gut-brain axis. Loss of natural urges, rectoanal dysfunction, and trauma from straining may become irreversible. The sooner you correct course, the more likely you are to recover fully without long-term damage and complete your diet successfully.

Naturally, after reading this list, takeaways, and self-analyzing yourself, your next question would be: Konstantin, what should I do, then? 

I recommend reading the following seven articles I have already written on this subject in the past and reviewing forty answers to constipation-related questions:

≫ How to Normalize Stools and Restore Natural Bowel Movements

≫ Dietary Fiber: The Bulls' S..t in the China Shop

≫ How to Overcome Fiber Dependence and Related Constipation

≫ Irritable Bowel Syndrome: A Latent Constipation in Disguise

≫ Diverticulosis and Diverticulitis: The Pinnacle of Stool Engineering

≫ Hemorrhoids and Anal Fissures: What Nature Giveth, Newton's Law Taketh

≫ How to Restore Anorectal Sensitivity

If you don’t have time to read, or you’re in a bind and need a reliable, long-term fix, check this page: Hydro-CM (Colonic Moisturizer) Program. It’s a long read, too, but it’s the only remedy I know that’s suitable for extended use, free of side effects, and has helped 81% of our clients. I’ve been taking it myself for the past 23 years, and that’s one of the reasons I know so much about this subject and why I’m still not wearing a diaper.

Frequently Asked Questions

And these are the answers to some of the most common questions that clients ask me again and again about constipation and related topics that you may find equally helpful.

 As you can see from the additional articles and the forty questions and answers above, constipation isn’t as trivial as it’s portrayed just about everywhere. And it doesn’t go away when you start taking laxatives but gradually gets worse and worse. I hope this won’t happen to you!

Please share this post with your family and friends to support my work!

Thank you!

Konstantin Monastyrsky