Why Are You Always Bloated? Is It Really IBS?
Do you experience bloating, excessive gas, constipation, diarrhoea, reflux, or alternating bowel habits — particularly after foods like garlic, onion, legumes, wheat, or milk?
If so, it may be worth looking beyond the label of “just IBS.”
For some people, these symptoms may be associated with alterations in the gut microbiome, including bacterial overgrowth within the small intestine or methane-producing microbes affecting gut motility and digestion.
Two terms commonly discussed in this space are:
SIBO — Small Intestinal Bacterial Overgrowth
IMO — Intestinal Methanogen Overgrowth
Understanding what these conditions are — and how they may contribute to digestive symptoms — can be an important step towards more targeted and individualised support.
What Are SIBO & IMO?
SIBO refers to an overgrowth of bacteria within the small intestine — an area of the digestive tract that naturally contains far fewer microbes than the large intestine. It is commonly associated with a looser stool pattern and/or alternating bowel habit.
IMO refers to an overgrowth of methane-producing microbes called methanogens. Methane production is more commonly associated with constipation and slowed gut motility, although presentations can vary considerably between individuals.
These microbial imbalances may contribute to symptoms including:
bloating and abdominal distension
excessive gas
constipation, diarrhoea, or alternating bowel habits
abdominal discomfort or cramping
reflux and nausea
food intolerances and heightened food sensitivity
fatigue and brain fog
restless legs
rosacea
Symptoms often overlap significantly with IBS, which is one reason these conditions may sometimes be overlooked.
IBS, Stress & The Gut–Brain Axis
The gut and nervous system are closely interconnected.
Stress, poor sleep, anxiety, nervous system dysregulation, and periods of chronic overwhelm may all influence digestive function, gut sensitivity, motility, and the gut microbiome itself.
For some individuals, symptoms may flare significantly during stressful periods, even when diet remains unchanged.
This is one reason why a comprehensive treatment approach must consider the gut-brain axis and it’s potential role in worsening symptom severity & ‘food fears.’
How Are SIBO & IMO Tested?
Hydrogen and methane breath lactulose, glucose & fructose breath testing are commonly utilised. Research setting utilise jejunal aspirates at times but these require endoscopy and aren’t commonly available outside of a research setting.
Breath testing involves drinking a preparation solution before providing breath samples over several hours to assess fermentation gas patterns.
Depending on the individual presentation, testing may sometimes be combined with advanced gut microbiome analysis to provide additional insight into broader gut ecosystem patterns, digestive function, inflammatory markers, and microbial balance.
Testing is always considered on an individual basis and alongside a thorough case history. My preferred breath testing supplier is Stream Diagnostics, a Melbourne based company - you can choose to test in the comfort of your own home or travel to Ringwood for onsite testing.
An Individualised Approach To Gut Health
There is no universal “gut protocol” suitable for everybody.
Treatment approaches differ significantly depending on a person’s symptoms, microbiome patterns, food tolerances, nervous system state, motility, health history, medications, and overall sensitivity.
Importantly, treatment is not about aggressively “killing” bacteria or excessive dietary restriction. In many cases, a more restorative, considered and individualised approach is more sustainable and effective— particularly for those with longstanding digestive symptoms or heightened gut sensitivity.
Looking Beyond “Just IBS”
IBS is often used as an umbrella diagnosis for chronic digestive symptoms, but it’s important to understand that not all IBS-type presentations are caused by SIBO or IMO.
Digestive symptoms can develop due to a wide range of overlapping factors involving the gut microbiome, diet, stress physiology, gut sensitivity, motility, infections, food intolerances, and the gut–brain axis.
However, SIBO and IMO are increasingly recognised as relatively common and clinically relevant contributors that may sometimes be overlooked — particularly in those experiencing persistent bloating, excessive gas, food intolerances, reflux, constipation, diarrhoea, or alternating bowel habits. From a clinical perspective, this presentation is relatively common in those later identified as having SIBO and/or IMO, making appropriate testing well worth discussing with your healthcare practitioner.
When Gut Symptoms Still Aren’t Making Sense
If you’re experiencing ongoing bloating, digestive symptoms, food intolerances, or feel like your gut health concerns still haven’t been fully explained, let’s work together to better understand what may be driving your symptoms and help inform the path forward.