There is a new term starting to emerge in relation to the low FODMAP diet and this is the modified low FODMAP diet.

Put simply this is the long term diet the majority of people follow after completing the reintroduction phase of the low FODMAP diet.

People with IBS who have been fortunate enough to see a dietitian will understand that there are actually 3 phases to a low FODMAP diet.  Those who could not get access to a dietitian or have chosen to try the low FODMAP diet themselves may probably not have realised the low FODMAP diet has 3 phases. Certainly if you obtain most of your information from the internet the reintroduction phase and the long term maintenance phase are rarely mentioned. I have to admit the research into FODMAPs and IBS is pretty slim on these important phases too! The figure shows these 3 phases and is explained below.

Three phases of the low FODMAP diet

So what are the 3 phases of the low FODMAP diet?

1. The first phase is the low FODMAP restriction (or elimination) diet. This is what most people know as the low FODMAP diet but this phase of the diet should only be followed for 2-6 weeks.

2. The second phase of the diet is the reintroduction phase. This involves both re-challenging and reintroducing FODMAPs to test your tolerance levels to FODMAPs and understand your FODMAP threshold. This phase takes about 10 weeks to complete. In a way it continues indefinitely as your tolerance to FODMAPs can change over time and you continue to re-challenge and reintroduce FODMAPs. More on reintroducing FODMAPs here.

3. The final phase is termed a modified low FODMAP diet. Once you have completed the reintroduction phase and reintroduced FODMAPs back into your diet most people will still restrict some high FODMAP foods. This combination of eating high FODMAP and low FODMAP foods to personal tolerance results in a modified low FODMAP diet.

The final terminology for these 3 phases has yet to be agreed or published but will be similar to what is discussed above. There is limited research available on what people do once they have completed the 2-6 week low FODMAP diet. Earlier this year I presented an abstract while working at King’s College London at the Digestive Diseases Federation conference which looked at the long term effects of the low FODMAP diet in the UK and answered some very interesting questions.


1. Do people reintroduce FODMAPs after starting a low FODMAP diet?


In fact 97 out of 103 people completed the reintroduction phase.

2. What sort of diet do people follow in the long term after completing the low FODMAP restriction diet and the reintroduction phase?

Out of the 103 participants when followed up one year later:
78 of them continued to follow an adapted low FODMAP diet. Meaning they had reintroduced FODMAPs to their own tolerance levels.
19 followed a normal diet. Meaning they had reintroduced FODMAPs and no longer followed any FODMAP restrictions.
6 continued to follow a low FODMAP restriction diet in the long term (a year later).

Therefore the vast majority of people do reintroduce FODMAPs but continue to follow a modified low FODMAP diet as their normal diet.

3. After you have reintroduced FODMAPs do you still have relief of your IBS symptoms in the long term?


There are two statistical points here. First of all 61% of people found relief of their IBS after following a low FODMAP restriction diet. This is similar to other studies looking at the effectiveness of the restriction phase of the low FODMAP diet. Importantly in those 61% of people 70% of them continued to have relief of their symptoms a year later.

This shows that in the vast majority of people who find the low FODMAP restriction diet effective, even once they have reintroduced FODMAPs they still have relief of their IBS symptoms in the long term.

The abstract is available here.

Following the low FODMAP diet long term. What is a modified low FODMAP diet?

The full programme from the event is available here.

It is great that these questions are starting to be answered as it helps the low FODMAP diet become a long term treatment option for IBS symptoms. It also means that the full information about the low FODMAP diet will become known to more people. Hopefully this will result in more support for those who are following only phase one of the low FODMAP diet and unnecessarily restricting their diet.

The study also looked at quality of life, the long term nutritional adequacy and acceptability of the diet with some really interesting findings which I will discuss in a later post.

Want more information on the low FODMAP diet and IBS? Click here for the latest changes and important updates.

We are currently travelling around the world and plan to bring you‘Around The World In 80 Low FODMAP Dishes’ – a collection of the best low FODMAP foods and recipes as we travel the globe. See more on our low FODMAP diet travel section.

Good news! The first ever book dedicated to reintroducing FODMAPs is now available to purchase on Amazon Kindle. The book is titled ‘Re-challenging and Reintroducing FODMAPs – A self-help guide to the entire reintroduction phase of the low FODMAP diet’. Click on the logo for more details.


More information on Reintroducing FODMAPs here.

Low FODMAP recipes here.

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Lee is a UK Registered Dietitian who worked as a researcher at King’s College London University researching the low FODMAP diet for irritable bowel syndrome (IBS). Previously Lee worked for the NHS with many years’ experience of treating IBS. Lee has run a popular blog on the low FODMAP diet since 2013 where you can learn all about his experiences of following the low FODMAP diet, find information on the research behind the diet, the practicalities of implementing the diet along with low FODMAP meal and baking recipes. This year Lee has published the first ever book dedicated to the reintroduction phase of the low FODMAP diet. More information on the book entitled ‘Re-challenging and Reintroducing FODMAPS: A self-help guide to the entire reintroduction phase of the low FODMAP diet’ can be found on the website

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