What is FODMAP Stacking
FODMAP “stacking” happens when you have too many low-FODMAP servings of food (or green servings in the Monash FODMAP App) in one sitting (a meal or snack). As a result, there is an accumulation of FODMAPs in the gut. For some people, this may lead to uncomfortable symptoms. Rest assured, if you never heard of this term and are having good symptom control with the elimination phase, you don’t need to worry about this! On the other hand, if the low FODMAP diet has not given you the relief in symptoms you were looking for, this could be one of the reasons why.
3 Key Things to Know to Avoid FODMAP Stacking
1. Know the difference between low and no FODMAP foods
To begin with, some foods have only trace amounts of FODMAPs or none at all. For example, quinoa, carrots, and kale can be eaten in large quantities without risking any gut symptoms. In addition, since FODMAPs are carbohydrates, animal proteins such as eggs, poultry, and fish, contain no FODMAPs at all. Therefore, you want to take advantage of these foods and incorporate them into most of your meals and snacks.
On the other hand, some foods are considered low FODMAP only at specified (often small) portions. For example, zucchinis are low FODMAP at a ½ cup serving (about 2 ounces). But larger quantities (starting at 3.5 ounces) are high in oligosaccharides, making them a high-FODMAP choice. You need to pay attention to the portion sizes of these foods, especially during the elimination phase.
Space your meals 3-4 hours apart. This will slow the rate at which your gut is exposed to FODMAPs. If you are constantly grazing, FODMAPs keep accumulating in your intestinal tract and expose your gut to too many FODMAPs at once. And this may lead to bloating and other uncomfortable symptoms.
2. Test your personal FODMAP threshold
Once you have reintroduced FODMAPs and discovered which high-FODMAP foods you can tolerate well, you need to test your tolerance to combinations of these foods and find out your personal FODMAP threshold. This is the exciting part of the personalization phase. You can start by combining two high-FODMAP foods in the same meal. For example, you may know you tolerate 1/2 an avocado (rich in sorbitol) and have no problem with the oligosaccharides in wheat bread, as you tested them separately in the reintroduction phase. Now you can try having avocado toast for breakfast.
3. Make sure you stack FODMAPs gradually: the effects are additive
Think of your gut as a bucket that can only be filled with a certain amount of FODMAPs before it overflows. Different people have different-size “buckets” and you need to figure out how big yours is. Let’s illustrate this concept.
A common mistake is starting to combine too many foods too soon. For example, one of the biggest triggers for symptoms is one of Americans’ favorite foods: pizza! Let’s say you know you can tolerate lactose (in the cheese), oligosaccharides (in the wheat crust and sauce – garlic or onions), and small amounts of mannitol (found in mushrooms). So, you decide to celebrate by going out and ordering a large pizza with mushrooms on your first pizza outing. Combining all those FODMAPs at once could trigger some symptoms.
Instead, it would be more prudent to start with a plain pizza (crust, tomato sauce, and cheese). And to eat only one slice at first. If you tolerate it, you can build up from that. Next time, you can try a slice of pizza with mushrooms or two slices of plain pizza. You get the gist: you make small steps and find out your personal thresholds for combining FODMAPs. In the end, you may very well be able to tolerate all the toppings you want!
FODMAP stacking is something you should be aware of if you are not having enough symptom relief on a low FODMAP diet. And also when you start personalizing your diet after you have discovered your triggers. Knowing which foods have a low FODMAP limit in serving size and which ones instead have no FODMAPs at all can help you avoid stacking. Once you are ready to personalize your diet, use your judgment and listen to your body. After a bit of trial and error, you will understand how to combine FODMAPs and be on your way to enjoying your favorite foods without experiencing gut symptoms.
If you are having trouble navigating any of the phases of the low FODMAP diet, I can help!
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Published February 27, 2018. Updated, June 12, 2023.