IBS and the Low FODMAP Diet: What You Need to Know

If you live with bloating, abdominal pain, constipation, diarrhoea, or unpredictable digestion, you may have been told you have Irritable Bowel Syndrome (IBS). IBS is one of the most common digestive conditions worldwide, yet many people feel confused about what actually helps.

One of the most well-known nutrition strategies for IBS is the Low FODMAP Diet. You may have seen it on social media or been told to “just cut out FODMAPs,” but the reality is more nuanced than that.

What is IBS?

Irritable Bowel Syndrome is a functional gastrointestinal disorder, meaning the digestive tract looks normal structurally but doesn’t function normally.

Common symptoms include:

• Bloating and abdominal distension

• Abdominal pain or cramping

• Diarrhoea, constipation, or both

• Gas

• Urgency or incomplete bowel movements

Symptoms can fluctuate over time and are often influenced by multiple factors, including diet, stress, gut sensitivity, and bowel motility.

Researchers now understand that IBS involves several overlapping mechanisms, including:

• Gut–brain axis dysregulation (communication between the gut and nervous system)

• Visceral hypersensitivity (the gut is more sensitive to normal digestion)

• Changes in gut motility

• Altered gut microbiome

• Food sensitivities, including certain carbohydrates (this is where the Low FODMAP diet can sometimes help)

What Are FODMAPs?

The Low FODMAP Diet was developed by researchers at Monash University to help reduce IBS symptoms.

FODMAP stands for:

Fermentable...

Oligosaccharides (Fructans & GOS)

Disaccharides (Lactose)

Monosaccharides (Fructose)

And

Polyols (Sorbitol & Mannitol)

These are short-chain carbohydrates that are poorly absorbed in the small intestine.

When they reach the large intestine, they can:

• Pull water into the bowel

• Be rapidly fermented by gut bacteria

• Produce gas and distension

  
  

For people with IBS, whose gut is often more sensitive, this can trigger symptoms like bloating, pain, diarrhoea, or constipation.

Common high FODMAP foods include:

• Onion and garlic

• Wheat products

• Apples and pears

• Milk and some dairy products

• Legumes

• Certain sweeteners like sorbitol

Importantly, these foods are not unhealthy. They only cause symptoms for some people with IBS.

The Three Phases of the Low FODMAP Diet:

The Low FODMAP Diet is not meant to be followed strictly forever. Instead, it is a structured process designed to identify individual triggers.

1. Elimination Phase (Short-Term)

This phase temporarily reduces high FODMAP foods for 2–6 weeks.

The goal is to:

• Reduce IBS symptoms

• Create a “baseline” for digestion

• Prepare for systematic reintroduction

This phase should be short-term and supervised, as it can be restrictive.

2. Reintroduction Phase

This is the most important step, but also the one people often skip.

Foods are reintroduced one FODMAP group at a time to test tolerance.

This helps identify:

• Which FODMAP groups trigger symptoms

• Which foods you can comfortably include

  
  

Most people discover they tolerate many more foods than they expected.

3. Personalisation Phase

The final phase builds a long-term, sustainable diet based on your personal tolerances.

The goal is to:

• Reintroduce as many foods as possible

• Support gut microbiome diversity

• Maintain symptom control

This phase looks different for everyone because IBS triggers are highly individual.

Why the Low FODMAP Diet Isn’t the First Step…

Although the Low FODMAP Diet can be very effective (helping around 70% of people with IBS), it is not always the first-line approach.Before starting a restrictive diet, it’s often important to address other key IBS factors.

These may include:

• Meal Patterns - Irregular eating patterns can worsen IBS symptoms.

• Fibre Type - Many people with IBS benefit from adjusting the type of fibre, rather than removing foods completely.

• Stress and the Gut–Brain Axis - IBS is strongly linked to the gut–brain connection.

• Other lifestyle Triggers e.g. tight clothing, poor sleep, high caffeine intake.

IBS Management Should Be Individual

The most important thing to know about IBS is that there is no one-size-fits-all solution.

Some people benefit greatly from the Low FODMAP Diet, while others see improvement by focusing on:

• Fibre balance

• Regular eating patterns

• Stress management

• Gut-friendly lifestyle habits

Working with a dietitian can help you avoid unnecessary restriction and find a personalised approach that supports both symptom relief and long-term gut health.

Need Help Managing IBS?

If you’re struggling with bloating, constipation, diarrhoea, or unpredictable digestion, you don’t have to figure it out alone.

As a dietitian specialising in IBS and digestive health, I help clients:

• Identify their personal triggers

• Navigate the Low FODMAP process properly

• Improve gut symptoms without overly restrictive diets

• Build a sustainable way of eating that supports both gut health and quality of life

If you’re ready to feel more confident with your digestion, book a consultation to start your personalised IBS plan.