What Is IBS? A Dietitian's Guide to Irritable Bowel Syndrome

If you're dealing with recurring digestive symptoms that disrupt your daily life, you're far from alone. Irritable Bowel Syndrome (IBS) is one of the most common gastrointestinal disorders in the world, affecting an estimated 1 in 7 people globally. Yet despite how widespread it is, IBS remains widely misunderstood — and many people suffer in silence for years before getting the right support.

As an accredited dietitian specialising in gut health, I want to give you a clear, evidence-based overview of what IBS actually is, what causes it, how it's diagnosed, and — most importantly — how it can be effectively managed.

What Is IBS?

Irritable Bowel Syndrome (IBS) is a chronic functional gastrointestinal disorder that primarily affects the large intestine (colon). Unlike inflammatory bowel diseases such as Crohn's or colitis, IBS does not cause visible damage to the gut — but it does cause very real, often debilitating symptoms.

Common symptoms of IBS include:

• Abdominal pain or cramping (often relieved by a bowel movement)
• Persistent bloating and distension
• Excessive gas
• Altered bowel habits — constipation (IBS-C), diarrhoea (IBS-D), or a mix of both (IBS-M)
• A feeling of incomplete emptying after a bowel movement
• Urgency to use the bathroom

Symptoms can range from mild and manageable to severe and life-limiting, and they often fluctuate over time.

What Causes IBS?

The exact cause of IBS is not fully understood, and it's likely that multiple factors contribute to its development. Current research points to several key mechanisms [1]:

• Gut-brain axis dysfunction — disrupted communication between the brain and the enteric nervous system can alter pain perception and gut motility
• Visceral hypersensitivity — the gut becomes overly sensitive to normal sensations like gas or digestion, interpreting them as pain
• Gut microbiome imbalance (dysbiosis) — an altered composition of gut bacteria has been consistently observed in people with IBS. Learn more in our post on the gut microbiome and IBS
• Altered intestinal motility — the gut moves too fast (diarrhoea) or too slow (constipation)
• Post-infectious IBS — IBS can develop following a gastrointestinal infection

Stress and psychological factors also play a significant role — not as a cause, but as a powerful amplifier of symptoms. Read more about the connection between stress and IBS.

How Is IBS Diagnosed?

There is no single test for IBS. Diagnosis is made clinically, based on your symptom history and the exclusion of other conditions. Your doctor will typically:

• Take a detailed medical and symptom history
• Perform a physical examination
• Order blood tests or other investigations to rule out conditions like coeliac disease, inflammatory bowel disease, or bowel cancer
• Apply the Rome IV criteria — the internationally recognised diagnostic framework for IBS, which requires recurrent abdominal pain at least one day per week for the past three months, associated with changes in bowel habits [2, 3]

Tip: Before your appointment, keep a symptom diary tracking your food intake, bowel habits, stress levels, and symptoms. This gives your healthcare team invaluable information and can significantly speed up the diagnostic process.

Common IBS Triggers

IBS symptoms are often triggered by specific foods, lifestyle factors, or stress. While triggers vary between individuals, some of the most common include:

Dietary triggers:

• High-FODMAP foods — learn more about FODMAPs here
• Large meals eaten quickly
• Carbonated drinks, alcohol, and caffeine
• Sugar-free products containing polyols (found in gum, mints, and some medications)
• Fatty or fried foods

Lifestyle triggers:

• High stress levels
• Poor sleep quality
• Irregular eating patterns or skipping meals
• Insufficient physical activity

Identifying your personal triggers is one of the most powerful steps you can take — and it's something a specialist IBS dietitian can help you do systematically and safely.

Managing IBS: A Holistic Approach

While there is currently no cure for IBS, the good news is that symptoms can be very effectively managed with the right combination of strategies. Evidence-based approaches include:

Dietary Management

The low FODMAP diet is the most well-researched dietary intervention for IBS, with studies showing symptom improvement in up to 75% of people who follow it correctly [5]. It involves a structured 3-phase process of elimination, reintroduction, and personalisation — and should always be undertaken with the guidance of a trained dietitian. Read our full guide to FODMAPs and the low FODMAP diet, and explore our low FODMAP meal planning tips.

Stress & Lifestyle Management

Given the strong gut-brain connection, managing stress is a non-negotiable part of IBS care. Effective strategies include mindfulness meditation, Cognitive Behavioural Therapy (CBT), regular exercise, and prioritising quality sleep [4]. See our detailed guide on stress management for IBS relief.

Medication

Depending on your IBS subtype and symptom severity, your doctor may recommend antispasmodics, laxatives, anti-diarrhoeal agents, or low-dose antidepressants. Medication works best as part of a broader management plan, not in isolation [6].

Professional Support

IBS is complex and highly individual. Working with a healthcare team that includes your GP, a gastroenterologist, and an accredited dietitian with IBS expertise gives you the best chance of achieving lasting symptom relief. You don't have to navigate this alone.

You're Not Alone — And You Don't Have to Just Put Up With It

Living with IBS can feel isolating, but connecting with others who understand your experience — whether through support groups, online communities, or working one-on-one with a specialist — can make a profound difference.

Explore our full library of dietitian-created IBS resources to support you at every stage of your journey.

Ready for a Structured, Expert-Led Plan to Manage Your IBS?

The IBS Program is a comprehensive, evidence-based resource created by an accredited dietitian to guide you through every aspect of IBS management — from understanding your triggers to following the low FODMAP diet correctly, with done-for-you meal plans, shopping lists, and symptom tracking tools.

It's everything you need to stop guessing and start feeling better.

→ Explore The IBS Program and take control of your gut health today

Further Resources

• Find an IBS-Trained Dietitian — Monash University Directory
• Monash University IBS Resources
• Dietitians Australia — IBS Information

References

[1] Chey, W. D., Kurlander, J., & Eswaran, S. (2015). Irritable bowel syndrome: a clinical review. JAMA, 313(9), 949–958.

[2] Lacy, B. E., et al. (2016). Bowel disorders. Gastroenterology, 150(6), 1393–1407.

[3] Palsson, O. S., et al. (2016). Development and validation of the Rome IV diagnostic questionnaire for adults. Gastroenterology, 150(6), 1481–1491.

[4] Ford, A. C., et al. (2014). Efficacy of prebiotics, probiotics, and synbiotics in irritable bowel syndrome and chronic idiopathic constipation. The American Journal of Gastroenterology, 109(10), 1547–1561.

[5] Staudacher, H. M., Whelan, K., & Irving, P. M. (2014). Lactose intolerance and the low-FODMAP diet. Journal of Gastroenterology and Hepatology, 29(3), 165–168.

[6] Chey, W. D., & Kurlander, J. (2015). Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date. Clinical and Experimental Gastroenterology, 8, 253–261.