IBS & Digestive Sensitivity: When the Gut Becomes Over-Reactive Rather Than Diseased

Irritable Bowel Syndrome, often shortened to IBS, is one of the most common digestive diagnoses worldwide — and one of the most frustrating to live with. People with IBS are frequently told that nothing is “wrong”, that tests are normal, and that they simply need to manage symptoms. At the same time, the symptoms themselves can be deeply disruptive, painful, unpredictable, and exhausting.

This contradiction lies at the heart of IBS.

IBS is not a disease of structural damage or tissue destruction. It is a condition of altered gut function and heightened sensitivity. The digestive tract is physically intact, but the way it moves, senses, and communicates has changed.

Understanding IBS requires a shift away from asking “What’s wrong with my gut?” and toward asking “Why is my gut responding this way?”

IBS Is a Disorder of Regulation, Not Damage

In IBS, routine digestive processes are experienced as uncomfortable, painful, or urgent. Normal amounts of gas feel excessive. Normal intestinal contractions feel crampy. Normal bowel movements feel unpredictable.

This happens because the gut becomes hypersensitive and poorly regulated, not because it is structurally broken.

The gut contains an extensive nervous system, sometimes called the enteric nervous system. This system communicates constantly with the brain, the immune system, and the microbiome. In IBS, signalling along these pathways becomes amplified and distorted.

The result is a gut that reacts too strongly to normal stimuli.

Visceral Hypersensitivity: The Core Feature of IBS

One of the defining features of IBS is visceral hypersensitivity.

This means the nerves in the gut become more sensitive to stretch, pressure, and movement. Gas that would go unnoticed in someone else becomes uncomfortable or painful. Normal bowel contractions feel urgent or cramp-like. Sensations that should remain below conscious awareness are amplified.

Importantly, hypersensitivity does not mean symptoms are imagined.

It means the volume knob on gut sensation has been turned up.

This heightened sensitivity is strongly influenced by stress, previous gut irritation, inflammation, and nervous system regulation. Once established, it can persist even after the original trigger has resolved.

Altered Gut Motility and Rhythm

Alongside hypersensitivity, IBS is characterised by altered gut motility.

In some people, the gut moves too quickly, leading to diarrhoea-predominant symptoms. In others, movement is sluggish, leading to constipation. In many cases, the gut alternates unpredictably between the two.

These motility changes are not random. They reflect altered communication between the gut and the nervous system.

Stress hormones, neurotransmitters, and gut hormones all influence how quickly food and waste move through the digestive tract. When these signals become dysregulated, rhythm is lost.

This is why IBS symptoms often fluctuate with stress, sleep, hormonal changes, and emotional load.

The Gut–Brain Axis in IBS

IBS is one of the clearest examples of the gut–brain axis in action.

The gut and brain communicate bidirectionally through neural pathways, immune signals, and chemical messengers. In IBS, this communication becomes overly reactive. Signals from the gut are amplified on their way to the brain, and signals from the brain exaggerate gut responses in return.

This creates a feedback loop.

Stress increases gut sensitivity and motility changes. Digestive symptoms increase stress. Over time, the nervous system becomes conditioned to expect discomfort, which further heightens vigilance and sensitivity.

This does not mean IBS is “all in the mind”. It means the mind and gut have become locked into a self-reinforcing pattern.

The Role of Inflammation and Immune Activation

Although IBS is not classically inflammatory in the way conditions like Crohn’s disease are, low-grade immune activation is common.

Following gastrointestinal infections, food poisoning, or periods of intense stress, immune cells in the gut can remain mildly activated. This ongoing immune signalling sensitises nerve endings and disrupts motility.

This is why IBS often begins after an acute illness or stressful life event and then persists long after apparent recovery.

The Microbiome and Fermentation Sensitivity

Gut microbes play a complex role in IBS.

Some people with IBS have altered microbial composition, while others have normal populations but heightened sensitivity to microbial activity. Fermentation of carbohydrates, which is a normal and beneficial process, may produce sensations that feel excessive due to visceral hypersensitivity.

This explains why foods that are otherwise healthy can trigger symptoms in some people with IBS, particularly when digestion upstream is compromised.

It is not that these foods are harmful. It is that the gut is reacting to them differently.

Hormones and IBS

Hormonal fluctuations strongly influence IBS symptoms, particularly in women.

Progesterone slows gut motility, often worsening constipation and bloating in the luteal phase of the menstrual cycle. Oestrogen influences gut sensitivity and fluid balance. Stress hormones directly alter gut movement and sensation.

This hormonal influence is another reminder that IBS is a condition of regulation rather than damage.

 

Diet and Lifestyle Factors That Commonly Worsen IBS and Sensitivity

IBS symptoms are often triggered or amplified by factors that increase gut reactivity rather than by single “problem foods”:

• Eating while stressed or rushed.
• Irregular meal timing and constant grazing.
• Large meals that overwhelm digestive capacity.
• Poor sleep and chronic psychological stress.
• Low digestive efficiency upstream.
• Sudden large increases in fermentable fibres.
• Long-term restrictive diets that reduce microbial diversity.
• Hyper-vigilance around food and symptoms.

Over time, these factors teach the gut to expect disruption.

 

Evidence-Based Strategies to Calm IBS and Digestive Sensitivity

The most effective approach to IBS is not aggressive elimination, but re-regulation.

Restore a Sense of Safety in the Gut

The nervous system must perceive digestion as safe for sensitivity to settle.

This begins with slowing meals, reducing distraction, and eating in predictable, calm patterns. Regularity matters more than perfection. When the gut learns that food arrives under non-threatening conditions, sensitivity gradually decreases.

Improve Digestive Efficiency Upstream

Ensuring adequate stomach acid and enzyme activity reduces the amount of poorly digested food reaching the intestines. This lowers fermentation load and immune irritation downstream.

Eating sufficient protein, avoiding constant snacking, and allowing time between meals often improves IBS symptoms without changing food choices dramatically.

Use Dietary Modifications Strategically, Not Permanently

Short-term reduction of highly fermentable carbohydrates can reduce symptom intensity during flares. However, long-term over-restriction often worsens sensitivity by reducing microbial diversity and increasing fear around food.

Reintroduction and personalisation are essential. The goal is tolerance, not avoidance.

Support the Gut–Brain Axis

Stress reduction is not optional in IBS management.

Gentle movement, breathing practices, nervous system regulation, adequate sleep, and psychological support where needed all help retrain gut–brain communication. As stress responses soften, gut sensitivity often follows.

Gradually Rebuild Resilience

IBS improves when the gut is exposed to manageable, predictable challenges rather than protected from everything.

Gradual fibre diversification, consistent routines, and reduced symptom vigilance help restore confidence in digestion. Over time, the gut becomes less reactive because it no longer needs to be on constant alert.

 

A Reframe

IBS is not a failure of digestion. It is a protective response that has become over-protective.

The gut is doing its best to signal distress, often after periods of stress, illness, or overload. With the right support, that signal can be turned down.

Most importantly, IBS is not a life sentence.

With understanding, patience, and strategies that prioritise regulation over restriction, digestive sensitivity can soften, symptoms can become predictable or minimal, and the gut can regain trust.

The goal is not perfect digestion. It is a gut that feels safe enough to stop shouting.