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What Is FODMAP Stacking?

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What Is FODMAP Stacking?

Simply put, if you are not paying attention to the AMOUNTS of foods that you eat and the COMBINATION of foods that you eat, then you risk FODMAP stacking.

Backround is fruits and vegetables on a table with a title What Is FODMAP Stacking atop of them.

Portions & Food Combination Choices Count!

When following the low FODMAP diet we are consuming amounts of foods in their various FODMAP levels, which initially can be determined by using the Monash University Low FODMAP Diet Smartphone App or the FODMAP Friendly App. These two resources will show you the lab tested amounts of FODMAPs in foods.

We do not recommend any other resources. Researchers at Monash University and FODMAP Friendly are the originators of the diet. Currently, these are the ONLY two entities that are lab testing foods for FODMAPs. Other apps present incorrect and/or incomplete information. Please stick with these apps – and do download them immediately if you have not already.

Monash University presents the traffic light system (Green for Low FODMAP; Yellow for Moderate; Red for High FODMAP) and much of the time will call out which individual FODMAP is involved. FODMAP Friendly has a system which always lists each type of FODMAP, as well as percentages of those FODMAPs, which can be used to assess stacking on a more micro level.

Ultimately the amount that is low FODMAP for YOU will be determined during a structured Challenge Phase, but the apps, which provide lab-tested results for individual foods, are the place to start.

Then we also have to pay attention to food AMOUNTS as well as what MULTIPLE FOODS we eat during the same meal or time frame. This article on What Is FODMAP Stacking? will explain what you need to know and why it is important.

Learn About The Different FODMAPS

First, it is important to understand that there are several types of different FODMAPS, which we explain in our article, What Are FODMAPs?

Brush up on Oligosaccharides, Disaccharides, Monosaccharides and Polyols before continuing.

FODMAP Stacking Explained

We have to first look at AMOUNTS:

The same food, such as almonds, can have a low FODMAP approved portion as well as a high FODMAP portion. This is why you might see almonds listed on low FODMAP food lists as well as high FODMAP food lists.

Neither is more right or wrong than the other. What is missing is the discussion of AMOUNTS and how it relates to you.

Monash app entry for Almonds
Screen capture of an entry in the Monash University Low FODMAP Diet App

As you can see from the Monash app above, almonds have a big Red Light next to them, indicating that they are high FODMAP. The app also tells us that the FODMAP in almonds is GOS (galacto-oligosaccharides). This is important for our stacking, so remember this fact.

But we don’t have the whole story yet. Look at the AMOUNT. One serving is somewhat arbitrarily* determined by Monash to be 20 nuts (24 g). At 10 nuts (12 g) almonds are at a recommended Green Light low FODMAP serving.

So now we know that a low FODMAP serving of 10 almonds (12 g) should be tolerated by most individuals with IBS. This is also very important to remember because it represents when almonds demonstrate a low FODMAP amount – in the lab.

You are NOT a lab, so while it is important to know what FODMAP amounts are, it is not the whole story.

* Serving sizes in the Monash app are somewhat determined by Australian Health Eating Guidelines, which are government guidelines, similar to the FDA in the U.S. The serving size amounts in the apps are NOT just based upon FODMAP level.

Let’s Look at the Type of FODMAP

Now let’s look at the type of FODMAP in the almonds – GOS.

The “O” in FODMAP stands for oligosaccharides (sometimes referred to as “Oligos”) — a category that comprises both fructans and galacto-oligosaccharides (GOS). This is a large and diverse category, populated with items from most of the major food groups.
You may want to read: All About Oligosaccharides

Here is where the stacking picture becomes more clear.

Hazelnuts are considered low FODMAP in servings of 10 nuts (15 g). They also contain GOS.

So, if you decide to make a little nut combo as a snack and eat a low FODMAP portion of BOTH almonds (10 nuts/12 g) AND hazelnuts (10 nuts/15 g) you will have STACKED your FODMAPs because they both contain the same FODMAP.

Now, let’s say you decide to have a different snack and combine the 10 almonds (12 g) with a small 125 ml glass of orange juice. Orange juice contains FRUCTOSE, but no GOS, so you would NOT be STACKING FODMAPs. This snack combo is low FODMAP.

FODMAP stacking is when you consume two or more foods in low FODMAP portions at the same time and the foods contain the same FODMAP(s)

BUT, whether this is ultimately an issue for YOU (remember you are not a lab) will be determined as you go through the diet and experience the diet and determine what works for you personally.

The “M” in FODMAP stands for monosaccharide. This is consistent with the rest of the acronym, which uses the first letter of the carbohydrate group each FODMAP belongs to, rather than that of a particular monosaccharide, which in this case is fructose.
You may want to read: All About Monosaccharides

Timing is Important

Stacking becomes an issue when foods containing the same FODMAPs are consumed at the same meal.

tiny white clock

Meals are assumed to be about 3 to 4 hours apart.

So, in theory, you could eat your 10 almonds (24 g) at breakfast and eat them again – or maybe eat those hazelnuts – at lunchtime and experience no ill effects.

Some dietitians also point out that since it can take quite a while for FODMAP symptoms to occur, that stacking could potentially occur within a 24 hour period. You can review a video Webinar lead by the team at Diet vs. Disease for more info.

Please also see our article on Timing of Digestive Symptoms: What It Means.

Individual Tolerance is What Counts Most Of All!

Whether an IBS symptom is triggered is a highly individual issue. Here is where your unique digestive system comes into play.

 One person might be able to actually eat 20 almonds (24 g) – DOUBLE the recommended amount – at one time and experience no symptoms.

Another person might only be able to tolerate HALF of the recommended low FODMAP amount and discover that 5 nuts (6 g) is what sits well with them.

And yet another person might learn that 10 almonds (24 g) is fine, but not twice in one day or even two days in a row.

a graphic of measuring cups and spoons with the text What is a Low FODMAP serving size
You may want to read: What Is A Low FODMAP Serving Size?

The low FODMAP diet is very nuanced and this is why we always recommend that you undertake the diet along with a registered dietitian to guide you.

The Challenge Phase in particular is best approached with help. We do suggest that you work with a Registered Dietitian (RD) for best results.

The Takeaway

The low FODMAP diet has many components. There are lab tested foods. There are published amounts of individual FODMAPs in foods. There are meals and recipes that you make in your own kitchens and eat out at restaurants that incorporate multiple foods and stack FODMAPs.

But the most important thing is how you react to FODMAPs yourself and learn to create what we call your own FODMAP Roadmap, that will keep triggers at bay.

Ultimately it doesn’t matter what any lab testing says. Remember, you are not a lab. 

Our goal is to provide you with the information that you need to be able to go forth and THRIVE on the low FODMAP diet!

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