Constipation: Causes, Wider Health Effects, and What Actually Helps

jadavisr
2 days ago
7 min read

Constipation is commonly defined as infrequent bowel movements, difficulty passing stool, or a feeling that the bowel has not fully emptied. Clinically, it is often described as fewer than three bowel movements per week, although frequency alone is not enough to assess bowel function properly. Stool consistency, ease of passage, bloating, abdominal discomfort, and the need to strain are all important considerations.

Normal bowel function depends on the digestive tract, nervous system, gut bacteria, and the muscles involved in emptying the bowel all working together properly. When stool moves too slowly through the bowel, several things begin to change. Gut bacteria have longer to ferment waste products, hormones that should be excreted can be reabsorbed, and substances produced during digestion remain in contact with the gut lining for longer than intended.

Over time, this can affect more than digestion alone. Energy levels, skin health, hormone balance, mood, and metabolic health can all be influenced by what is happening in the gut.

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Constipation: What Happens When Bowel Transit Slows

The colon is designed to absorb water from stool before it leaves the body. If stool remains there for too long, too much water is removed, making stools harder, drier, and more difficult to pass.

At the same time, bacteria continue to break down and ferment waste material. This can increase gas production, bloating, and irritation within the gut. Slower transit also increases the likelihood that certain compounds, including hormones and bacterial by-products, will be reabsorbed back into circulation instead of being eliminated.

The Nervous System and Constipation

Bowel motility is controlled by the autonomic nervous system, particularly the parasympathetic nervous system, sometimes referred to as the “rest and digest” state.

This system controls peristalsis, the wave-like muscular contractions that move food and waste through the digestive tract.

When the body spends long periods in a heightened stress state, digestion is not prioritised. Blood flow and nervous system signalling shift away from the gut, which can slow motility and reduce digestive secretions.

This is one reason why chronic stress, poor sleep, irregular eating patterns, and constantly rushing through meals can all contribute to constipation.

The gut also responds well to routine. Regular meal timing, adequate sleep, movement, and eating in a more relaxed state can all help support healthy motility.

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Constipation & Fatigue

One of the less obvious effects of chronic constipation is fatigue.

When stool remains in the bowel for longer than intended, there is increased exposure to bacterial by-products such as lipopolysaccharides (LPS). If these cross into circulation, they can stimulate inflammatory pathways within the body. Low-grade inflammation has been shown to interfere with energy production within cells, particularly within the mitochondria.

This can contribute to persistent tiredness, poor concentration, and feeling physically drained.

Constipation; Weight Gain and Metabolic Health

Constipation is increasingly being looked at within the wider picture of metabolic health.

The gut microbiome plays a role in appetite regulation, blood sugar balance, inflammation, and how efficiently calories are extracted from food. Changes in gut bacteria associated with slower bowel transit may contribute to weight gain or make fat loss more difficult.

Bile acids are also relevant here. These are released into the digestive tract to help break down fats, but they also act as signalling molecules involved in glucose regulation and insulin sensitivity. Slower bowel transit alters how these compounds are recycled and processed.

This overlap between gut function and metabolic health is one reason why constipation is often present alongside weight gain, insulin resistance, raised cholesterol, and central fat accumulation.

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Constipation & Skin Health

The gut and skin are closely connected through immune and inflammatory pathways.

When bowel function is sluggish, inflammatory compounds and bacterial metabolites can remain in circulation for longer. This may contribute to acne, congested skin, inflammatory skin conditions, or a dull complexion.

In some cases, skin symptoms improve significantly when bowel function and gut health are addressed.

Constipation & Small Intestinal Bacterial Overgrowth

Small Intestinal Bacterial Overgrowth, or SIBO, occurs when excessive numbers of bacteria are present in the small intestine.

One of the body’s main protective mechanisms against this is normal gut motility. Between meals, the digestive tract produces cleansing waves known as the migrating motor complex, which help move bacteria and debris through the small intestine.

When motility slows, bacteria can remain and multiply where they should not. These bacteria ferment carbohydrates from food, producing gas, bloating, abdominal distension, and sometimes constipation itself.

In this way, constipation and SIBO can reinforce each other.

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Constipation & Hair Thinning and Brittle Nails

Hair and nail health can be affected when digestion and absorption are not functioning well.

Chronic constipation may be associated with reduced digestive efficiency, changes in the gut microbiome, and altered absorption of nutrients involved in hair and nail growth.

Iron is essential for oxygen delivery to rapidly growing cells such as hair follicles. Zinc is involved in tissue repair and keratin production. B vitamins also play important roles in cell turnover and energy production.

If these nutrients are low, hair shedding, poor hair growth, and brittle nails can develop.

Constipation & Immune Function

A large proportion of the immune system is located within the gut.

The intestinal lining and gut microbiome constantly interact with immune cells, helping regulate inflammation and immune responses. When bowel transit is slow and microbial balance changes, immune signalling may also change.

This can contribute to ongoing low-grade inflammation or reduced resilience to infections.

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Constipation & Oestrogen Balance

Oestrogen is processed by the liver and excreted into the bowel through bile.

Certain gut bacteria produce enzymes that can reactivate oestrogen, allowing it to be reabsorbed into circulation rather than eliminated. When bowel movements are infrequent, there is more opportunity for this to occur.

Over time, this may contribute to symptoms associated with excess oestrogen, including heavy periods, breast tenderness, fluid retention, and weight gain around the abdomen.

Constipation & Mood & Anxiety

The gut and brain communicate constantly through the nervous system, immune pathways, and chemical signalling.

Gut bacteria are involved in the production of neurotransmitters and other compounds that influence mood and stress responses. At the same time, inflammation originating in the gut can affect brain function and nervous system regulation.

This is one reason digestive symptoms and low mood, anxiety, or poor stress tolerance are often seen together.

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Practical Strategies to Improve Bowel Function

Establish Your Baseline

Before making changes, it helps to assess what your current bowel pattern actually looks like.

Pay attention to:

Frequency of bowel movements
Stool consistency
Whether you need to strain
Whether you feel fully emptied afterwards

Ideally, bowel movements should occur most days, stools should be soft but formed, and they should pass without significant effort.

Support the Nervous System

Because bowel motility is controlled by the nervous system, this is a key area to address.

Helpful strategies include:

Eating meals sitting down and without rushing
Avoiding eating while distracted or stressed
Allowing enough time in the morning rather than rushing straight out the door
Prioritising regular sleep patterns
Building pauses into the day to reduce constant sympathetic nervous system activation

Even simple measures such as slow breathing before meals can help shift the body into a state more supportive of digestion.

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Improve Meal Structure and Routine

The bowel responds well to regularity.

Helpful changes include:

Eating meals at similar times each day
Avoiding long periods without food followed by very large meals
Chewing food thoroughly
Including protein, healthy fats, and fibre with meals to support digestive signalling

Increase Fibre Gradually

Rapidly increasing fibre can worsen bloating and discomfort, particularly if there is underlying dysbiosis or SIBO.

A more effective approach is to increase gradually:

Add vegetables to at least two meals daily
Include berries, kiwi fruit, or stewed fruit regularly
Introduce flaxseed or chia seeds slowly, starting with one teaspoon daily

Hydration

Fluid intake also needs to increase alongside fibre.

Four glasses of ice water on a rustic wooden table. The clear glasses and cool water create a refreshing and serene atmosphere.

Adequate fluid intake is essential for stool consistency.

A rough guide is around 30 to 35 ml of fluid per kilogram of body weight daily, although requirements vary depending on activity levels, caffeine intake, and climate.

Many people benefit from starting the day with water shortly after waking, particularly if bowel movements are sluggish in the morning.

Movement

Physical movement stimulates bowel motility.

Walking after meals can be particularly effective, as it helps stimulate peristalsis and supports blood sugar regulation at the same time.

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Magnesium

Magnesium helps regulate muscle contraction and relaxation within the bowel.

Some people benefit from increasing magnesium-rich foods such as leafy greens, nuts, and seeds, while others may require supplementation. Different forms have different effects, so this should be individualised.

When to Investigate Further

If constipation is persistent, severe, associated with significant bloating, or occurring alongside symptoms such as fatigue, skin issues, hormonal symptoms, or weight changes, further investigation may be appropriate.

Functional testing may include:

Comprehensive stool analysis
Breath testing for SIBO
Gut barrier testing
Blood tests assessing thyroid function, iron status, inflammation, and metabolic markers

This can help identify whether the main drivers are related to motility, microbial imbalance, inflammation, nervous system regulation, or other underlying factors.

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Frequently Asked Questions

Is it normal not to open your bowels every day?

There is some variation between individuals, but consistently going fewer than three times per week, needing to strain regularly, or feeling incompletely emptied suggests bowel function is not optimal.

Can stress really affect constipation?

Yes. Stress affects the autonomic nervous system, which directly controls gut motility and digestive secretions. Chronic sympathetic nervous system activation can slow peristalsis significantly.

Can fibre make constipation worse?

It can. If bowel motility is poor or there is significant bacterial overgrowth, increasing fibre too quickly may increase bloating and discomfort rather than improve symptoms.

What are signs that constipation may be affecting wider health?

Persistent bloating, fatigue, skin changes, hormonal symptoms, headaches, poor concentration, and difficulty losing weight can all occur alongside chronic constipation.

When should constipation be investigated properly?

If symptoms are persistent, worsening, associated with pain or bleeding, or affecting quality of life, further assessment is appropriate.

Summary

Constipation involves far more than bowel frequency alone. It reflects changes in gut motility, nervous system regulation, microbial activity, and elimination.

When bowel function is consistently sluggish, the effects may extend into energy levels, skin health, hormone balance, mood, and metabolic health. Addressing constipation properly therefore involves understanding and supporting the wider systems involved, rather than focusing only on short-term symptom relief.

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Free 30-Minute Health Chat

If you are struggling with ongoing constipation, bloating, fatigue, hormonal symptoms, or feel that your digestion is affecting other areas of your health, it may be helpful to take a more detailed look at what is driving it.

I offer a free 30-minute health chat to discuss your symptoms, health history, and whether nutritional therapy and functional testing may be appropriate for you.

You can use this time to ask questions, talk through your concerns, and explore the next steps in a supportive and practical way.

To book your free 30-minute health chat, follow this link: https://calendly.com/jadavisr/30min

References

Bharucha, A. E. et al. (2013). American Gastroenterological Association technical review on constipation. Gastroenterology.
Camilleri, M. (2019). Management of chronic constipation in adults. New England Journal of Medicine.
Cani, P. D. et al. (2007). Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes.
Ridlon, J. M. et al. (2016). Bile acids and the gut microbiome. Current Opinion in Gastroenterology.
Cryan, J. F. & Dinan, T. G. (2012). Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience.