Lifestyle | Health & Wellness

Can Your Tolerance To FODMAPs Change Over Time?

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Yes! Your tolerance to FODMAPs can change, and in fact, it is more likely that your tolerances will change, than stay the same. 

Let’s say you are following the low FODMAP diet, and as you move through the 3 phases of the diet you notice that you do not always react to FODMAPs in the same way. At one point eating a bowl of oatmeal sits well with your digestive tract, and yet on another day it does not. Let’s explore why.

One caveat from our Success Team dietitian Jessica Roocroft RD, if changes are sudden or severe, head to your doctor right away. This article is about the normal – and to be expected – variable reactions to FODMAPs that occur with all of us at one time or another.

Set Aside Variables

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First, let’s eliminate variables for sake of discussion. On any given day there could be non-food triggers that affect your IBS symptoms. Maybe you did not sleep well, or maybe you are experiencing hormone fluctuations, or undue stress? All of these things can trigger IBS (irritable bowel syndrome) symptoms, but for this discussion let’s say that none of those are occurring right now.

In addition, there could be non-FODMAP IBS triggers. Caffeine, meals that are high in fat, alcohol, and spicy food are just a few non-FODMAP triggers that occur quite regularly. Again, let’s say that none of those have come into play so that we can focus on FODMAPs.

Everyone’s approach to the low FODMAP diet is going to look different depending on myriad factors (which is why we caution you about seeking guidance from others on social media).

Why Your FODMAP Tolerance Changes

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Your tolerance to FODMAPs can change – and most likely will. You can become less triggered, and you can also become more triggered. We are going to look at all sides of this issue.

FODMAP Tolerance Increases

When we say FODMAP tolerance increases, we mean that you experience fewer IBS triggers from FODMAPs. 

This can often happen for people after they move through a structured Elimination Phase. If you work with a Registered Dietitian who has helped structure the right Elimination Phase approach for you, and it turns out that you are sensitive to FODMAPs, then very often at the end of this initial stage you will be experiencing relief. Your digestive tract will have calmed down and it will be optimally primed to begin food challenges. (PS: Many dietitians can meet with you remotely. You can find the right one for you!)

Please note that if you are having trouble at this stage, it could be that your approach to the diet is not appropriate and customized correctly for you. Everyone’s approach to the low FODMAP diet is going to look different depending on myriad factors (which is why we caution you about seeking guidance from others on social media). For instance, about 36% of you will have concurrent digestive issues; there could be other medical concerns such as diabetes or diverticulitis; there could be medications that need to be considered, as well as lifestyle. This is why the diet was always meant to be undertaken along with a Registered Dietitian to make sure that the diet is tailored to your needs.

You might take a look at our articles on Top Reasons to Work with a Dietitian, and also How To Choose a Dietitian.

At this point when you begin the second Challenge Phase, it is not unusual for people to discover certain levels of FODMAPs that are tolerable for them that they did not know or think they could tolerate before.

Part of this is because you took the time to calm your system down and create a baseline with a well-done Elimination Phase, and part of it is because you are looking at foods in a structured way in isolation, so that you can get the data you need about what you tolerate and what you don’t.

FODMAP Tolerance Decreases

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When we say FODMAP tolerance decreases, we mean that you experience more IBS triggers from FODMAPs. 

It is not unusual for people to report that something they were tolerating before is not being tolerated at a later date. This can occur at any time.

We know that we said we were excluding other triggers for the sake of discussion, but very often when someone reports a reaction to a food that they never reacted to before, we find that non-FODMAP triggers are not being considered and could be the culprit. Non-FODMAP triggers are quite common and should not be overlooked. 

But there are other reasons for your FODMAP tolerance to change.

FODMAP Tolerance Changes From Before

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Did you know that your digestive tract is not static? It’s true, and your gut microbiome is key to this discussion.

The gut microbiome is made up of trillions of microbes living in your gut (aka your gastrointestinal tract, which begins in the mouth and ends with the anal canal). Our whole body and mind health is intertwined with a diverse and rich microbiome. 

When it comes to digestion, a healthy microbiome supports a strong gut lining, and helps to break down food⁠. In addition, the microbiome can fluctuate easily [1]. 

The composition of an individual’s gut microbiota is unique, and tends to remain relatively stable over time, although daily fluctuations occur. What we eat has a significant impact on our gut microbiota. While changes in the gut microbiota can occur due to dietary shifts, these alterations appear to be temporary [1].

Our point is, that these fluctuations happen – and they could be part of the reason your FODMAP tolerance changes as well. These minor microbiota fluctuations will happen without you even being aware of them – and they are nothing to worry about. 

In addition, occasional negative reactions to FODMAPs are nothing to obsess over, either.

Long Term Relationship to FODMAPs

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Instead of focusing on certain days where you are at a loss to explain a reaction to FODMAPs that feels like an outlier, it is prudent to take a long term approach.

One of our pet peeves is when the low FODMAP diet is described as not a long-term diet. Even doctors will mistakenly use this verbiage. What this is referencing is the initial Elimination Phase, which is meant to be short. The diet itself, however, is three phases and the final Integration/Personalization Phase is not only long term, but also varied.

By the time you get to the third phase, you will have identified what your main FODMAP IBS triggers are, and tailor your diet accordingly. The goal of the diet is to eat as broadly as possible, without triggering your IBS. This is for the optimal health of your microbiome, as well as for your enjoyment of food, physically and emotionally. 

If there are certain foods, or amounts of foods, that you have not tolerated, wait a few months, and challenge yourself again. Your tolerances can change, and it is not unusual for people to be able to tolerate more foods (and/or greater quantities) down the line. The opposite can be true as well, but we do often see improvement in tolerances.

The Takeaway

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Your tolerance to FODMAPs can vary day to day, and month to month for a variety of reasons.

Be aware of non-FOMAP triggers. Do not discount them.

For example, folks with IBS with Diarrhea (IBS-D) who have a particularly bad diarrhea day may not realize how sensitive their gut is to insoluble fibre or “roughage”. On the flip side, those with constipation-predominant IBS may attribute a flare up to FODMAPs, when in fact they’re experiencing a day when they’re particularly backed up with stool. Read more about the IBS Subtype-specific factors that can play a role in your IBS picture.

If you have an “off” day, try not to obsess. IBS is not life threatening and your body will rebound. Read our article, How to Relieve an IBS Attack.

Wherever you are in the diet, just keep proceeding, even after an IBS trigger. 

If you are truly backsliding, and more and more IBS triggers are present than before on a regular basis, please discuss with your Registered Dietitian.

If you “fail” some Challenges initially, be sure to challenge again at a later date. Very often people discover they can tolerate foods (or amounts) that they did not before.

Remember that varied tolerance to FODMAPs is not unusual at all. There is nothing “wrong”. Our bodies and minds present a different microcosm every day.

Work with a Registered Dietitian to make sure you are following the low FODMAP diet in the best way for you, that you understand the process is not a straight line, and that the progression (and results) of moving through the diet will look different for each and every person. 


1. Emily R Leeming, Abigail J Johnson, Tim D Spector, and Caroline I Le Roy (2019). Effect of Diet on the Gut Microbiota: Rethinking Intervention Duration.

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