What is a low FODMAP diet?

By Courtney MorettiHealth & Wellbeing

The low FODMAP diet is a specialised dietary approach used to help manage symptoms of Irritable Bowel Syndrome (IBS).

It is not a general “healthy eating” diet and it is not intended to be followed long term. Instead, it is a structured process designed to identify which carbohydrates trigger gut symptoms in individuals with IBS.

What Is a FODMAP?

FODMAP is an acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.

These are types of carbohydrates that can be poorly absorbed in the small intestine. In people with IBS, this poor absorption can lead to symptoms such as:

  • Bloating

  • Gas

  • Abdominal pain

  • Diarrhoea

  • Constipation

  • Nausea

FODMAPs draw water into the bowel and are fermented by gut bacteria, which is what contributes to these symptoms in sensitive individuals.

Who Is the Low FODMAP Diet For?

The low FODMAP diet is designed specifically for people with IBS.

It is not appropriate for everyone and should not be used as a general elimination diet. Other medical conditions, such as coeliac disease, need to be ruled out before starting this approach.

Because of its complexity, the low FODMAP diet should be implemented with the guidance of an Accredited Practising Dietitian.

How Is the Low FODMAP Diet Done?

The low FODMAP diet is completed in three structured phases.

Phase 1 – Elimination

This phase involves removing high FODMAP foods from the diet for around 2 to 6 weeks.

The goal is to reduce gut symptoms and allow the digestive system to settle. This phase is temporary and not intended to be followed long term.

Phase 2 – Reintroduction or Challenge Phase

During this phase, FODMAPs are gradually reintroduced one group at a time over 6 to 8 weeks.

This helps identify which specific FODMAP groups trigger symptoms and which are tolerated. This step is essential and often skipped, which can lead to unnecessary long-term restriction.

Phase 3 – Personalisation

The final phase focuses on long-term symptom management.

Foods are reintroduced based on individual tolerance, allowing for the most varied diet possible while still managing symptoms. This personalised approach supports gut health, nutrition adequacy and quality of life.

Common High FODMAP Foods

Some examples of high FODMAP foods that may trigger symptoms include:

  • Onion and garlic

  • Cabbage and asparagus

  • Pears and mango

  • Regular yoghurt and soft cheeses

  • Wheat-based breads

  • Cashews and pistachios

Not everyone will react to all high FODMAP foods, which is why the challenge phase is so important.

Common Low FODMAP Foods

During the elimination phase, low FODMAP foods may include:

  • Lactose-free milk and yoghurt

  • Bananas and oranges

  • Hard cheeses

  • Meat, fish and eggs

  • Gluten-free breads and pastas

  • Rice and quinoa

  • Cucumber and zucchini

  • Peanuts

These foods provide a foundation for balanced meals while symptoms are being managed.

What to Expect When Starting a Low FODMAP Diet

Starting a low FODMAP diet can feel overwhelming at first.

The full process, including the reintroduction phase, can take 12 to 14 weeks. While this can feel challenging, completing the full process allows you to clearly identify personal triggers and avoid unnecessary long-term restriction.

Working with a dietitian can help make this transition smoother, ensure nutritional adequacy and provide practical strategies for shopping, eating out and meal planning.

There are now many more low FODMAP products available in supermarkets, including lactose-free dairy options.

The Monash University Low FODMAP Diet App is also a valuable resource. It provides up-to-date information on high and low FODMAP foods, portion sizes and recipes.

Beyond Food – Other IBS Triggers

Food is not the only trigger for IBS symptoms.

Stress, anxiety, sleep disruption and lifestyle factors can all influence gut symptoms. Managing IBS often requires a holistic approach that considers both nutrition and non-dietary factors.

Key Takeaways on the Low FODMAP Diet

The low FODMAP diet is a short-term, structured approach designed to identify food triggers for people with IBS.

When completed correctly and with professional guidance, it can significantly improve symptoms while allowing for the most varied diet possible long term. It is not about lifelong restriction, but about understanding your own tolerance and building confidence with food again.

If you are struggling with ongoing gut symptoms or feel unsure how to navigate a low FODMAP approach safely, personalised support can make a big difference. Nutrition consultations can help you find a nutrition plan that works for your body, your symptoms and your lifestyle, without unnecessary restriction or guesswork.