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The Three Phases of the Low FODMAP Diet

Updated: Jan 6, 2022

Why is going through all three phases of the Low FODMAP diet important?


People who experience IBS are often afraid of attending social occasions or is always on the lookout for the nearest toilet – this is because their symptoms can be unexpected and sometimes be embarrassing when you have to leave a gathering early or run to the toilet because of abdominal pain, wind or diarrhoea.

When people with IBS consume high FODMAP (Fermentable, Oligosaccharides, Disaccharides, Monosaccharides And Polyols) foods, it can cause intestinal distress leading to symptoms such as gas, bloating, abdominal pain, diarrhoea and/or constipation. Therefore the Low FODMAP diet involves lowering an individual’s overall ‘FODMAP load’ to help reduce symptoms.

The Low FODMAP diet has shown to improve symptoms in 75% people with IBS. Whilst it may not provide complete symptom relief, it can significantly improve their quality of life. So why is it NOT recommended to stay on this diet for long term if it can provide such positive benefits? Here are a few reasons why:

1. Not everyone is intolerant to all FODMAP groups.

There are six FODMAP groups: Fructose, Fructans, Galacto-oligosaccharides (GOS), Mannitol, Sorbiotl and Lactose. Studies have shown that people with IBS often are not intolerance to all of these six groups and can have varying dosage tolerances. For example, someone may not be able to tolerate small servings of fructose but is able to enjoy lactose at large amounts. Therefore, it is important to go through the second phase of the FODMAP diet: challenge or reintroduction stage where individuals test each FODMAP group at varying serving sizes (or dosage) to determine their personal level of tolerance.

2. It is a restrictive diet, limiting many food options.

The Low FODMAP diet is restrictive and can be challenging for many. It limits food options including fruits, vegetables, wholegrains, dairy and plant-based proteins. This can be difficult to follow especially when eating out or simply figuring out what to cook at home. Our dietitians can assist with providing eating out tips and meal ideas for initial stages of the diet – however we do recommend to go through all three phases so you don’t have to restrict your diet unnecessarily (as per point 1)

3. FODMAPs are important for good gut health

Good gut health is important not only for symptom management but also preventing chronic diseases such as diverticular disease, Inflammatory Bowel Disease or Bowel Cancer. FODMAPs are carbohydrates that ferment in your gut to feed the good gut bacteria for a healthy microbiome. Many higher FODMAP foods such as onion, garlic and wholegrains are also important source of prebiotics – a form of dietary fibre to feed the good bacteria, and when you start the Low FODMAP diet you naturally reduce many of these foods. Therefore, it is easy to neglect eating a balanced diet including dietary fibre during the initial stages of the diet, which often leads to constipation and/or exacerbation of digestive symptoms. This reiterates the importance of going through all three phases of the diet to determine if your personal tolerance of these foods.

Our dietitians are experienced and trained in the Low FODMAP diet, and will ensure you are still eating adequate amounts of fibre and gut-nourishing foods throughout all three phases.

4. It may not be for everyone

As suggested, the Low FODMAP diet has shown to improve symptoms in at least 75% people with IBS. However, this also means 25% people may not receive adequate symptom relief through this diet alone. Each person’s trigger to digestive symptoms is different and will require unique approaches. This includes diet – the Low FODMAP diet is not the only dietary strategy so people who ‘fail’ in the first phase should not fret because there can be alternative ways to manage their symptoms. Our dietitians will be able to help you with other dietary strategies if the Low FODMAP diet is not for you.


The Happy Gut Program by Four Seasons Dietetics is designed to guide individuals through the Low FODMAP diet with ease which includes providing a detailed investigations on personal triggers, nutritious and balanced meal ideas and also work with you on potential lifestyle factors that may be causing your symptoms. Click here to learn more about the Happy Gut Program.

Book an appointment with our IBS expert dietitian to start your IBS diet journey.

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