FODMAP Stacking Q & A with Monash University

FODMAP stacking is a super confusing topic when you are on the low FODMAP diet. But is it a concept you need to worry about? In our latest FODMAP Chat, we want to clear up the confusion with registered dietitian Chloe Swiney from the Monash FODMAP team.

This article will cover the following:

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FODMAP Stacking Chat Notes

Host: Alana Scott from A Little Bit Yummy

Monash University FODMAP Dietitian: Chloe Swiney

What is FODMAP Stacking?

The FODMAP stacking concept refers to when you eat multiple servings of green-rated (low FODMAP) foods in one meal and there is a potential for those foods to stack up and cause symptoms due to a build-up of FODMAPs. Even foods with green low FODMAP cut-offs might contain small amounts of FODMAPs. Eating these foods alone is not enough to cause symptoms; however, when you eat them together, those little bits of FODMAPs add up and can sometimes tip you over your tolerance levels and trigger gut symptoms.

Essentially FODMAP stacking is the accumulation of small amounts of FODMAPs eaten in one meal that can trigger symptoms.

Who needs to worry about FODMAP stacking?

You don’t need to worry about FODMAP stacking, especially when starting the low FODMAP diet.

The Monash University green light (low FODMAP) servings are conservative. We know that people don’t just eat single foods all the time, so we want people to be combining foods into meals. The conservative cut-offs enable you to eat multiple green servings of food without having FODMAP stacking issues.

We only want people to think about FODMAP stacking if they can’t shake their gut symptoms after a couple of weeks of being on the low FODMAP diet. The first elimination phase of the diet can last for 2-6 weeks, so if you’re getting to that 4-6 week period or longer and are still experiencing significant symptoms, then it’s time to seek help from a FODMAP-trained dietitian.

Otherwise, most people with Irritable Bowel Syndrome on the FODMAP diet experience a reduction of symptoms by just reducing the overall intake of FODMAPs in their diet and won’t even need to consider FODMAP stacking.

Take home message: Most people don’t need to worry about FODMAP stacking. Only look at FODMAP stacking with the help of a dietitian if you haven’t had good symptom reduction on the low FODMAP diet after 4 weeks.

What are green light serves and what do they mean?

Green light servings for foods are listed in the Food Guide of the Monash University FODMAP Diet App. The food guide shows all foods that have been laboratory tested for FODMAPs by Monash University and assigned a FODMAP rating. The app has cut-off levels for all of the different FODMAP groups that indicate when they might cause symptoms.

The green light is a rating given to serving sizes and foods with levels of FODMAPs that are not likely to trigger gut symptoms.

Other ratings include amber, which indicates moderate levels of FODMAPs that may cause symptoms in some people.

Finally, a red light indicates high levels of FODMAPs. For people with intolerances to the particular FODMAP groups in the food, this level of FODMAPs is likely to trigger symptoms.

The different ratings help you understand the portion sizes you can enjoy while on the first phase of the low FODMAP.

The key message is that you can still eat foods that contain FODMAPs. Often foods have different serving sizes with different FODMAP ratings. The food can have a red light at a larger serving size, but you can still eat the smaller green-rated serving size as that serving size is unlikely to cause symptoms. So you often don’t need to avoid foods altogether.

Lists that say to avoid these high FODMAP foods completely often aren’t that very useful, instead look for something that gives you a serving size like the Monash University FODMAP Diet App.

Take home message: Remember you can combine multiple green light serving sizes without worrying about symptoms.

Does FODMAP stacking happen across one meal or an entire day?

The great thing is that FODMAP stacking only happens across a meal. Please don’t try and track FODMAP stacking over the course of a day, that is so burdensome and not particularly useful. Here’s why:

Let’s think about your digestive system – when you eat your breakfast, it goes into your stomach, then passes into your small intestine, and then onto your large intestine. So if you leave enough time between that meal and the next, the food from breakfast has already passed into a different area of the digestive system. This spacing means those meals aren’t crossing over, so they can’t stack together.

Our top tip is to leave 2 to 3 hours between meals to give your body a chance to ‘reset’ before moving on to your next meal.

How do you manage FODMAP stacking if you are a constant grazer and always like to be snacking? Do you have tips on making the most out of regular meals to reduce the need to snack?

The key is to look at how you are making your meals. The goal is to make the meals filling by adding protein and fibre-containing foods that will fill you up. Combining protein and fibre can reduce that feeling of needing to snack again after 30 minutes.

Or if you just like snacking, then focus on choosing snacks that are really low FODMAP, so you don’t need to worry about the stacking:

canned tuna (by itself or add it to rice crackers)
carrot sticks with homemade eggplant dip
firm banana
popcorn
a handful of low FODMAP nuts

Another tip is to look for foods that only have the green light in the Monash University FODMAP Diet App. These foods are more likely to have minimal FODMAPs in them.

Are there any tips you can give us to avoid FODMAP stacking with fruit?

We recommend spreading your fruit throughout the day, for example, one serving of fruit in the morning and one for your afternoon tea or dessert, instead of having them all together. This recommendation is because when you eat multiple servings of fruit together, there is a higher chance of FODMAP stacking.

If you like having a fruit salad, try having half a serving of each fruit. For example, half a firm banana and then one or two strawberries. Then later in the day you can have a little bit more. Spreading out your servings throughout the day will reduce your chances of having FODMAP stacking issues from fruit.

Also be careful if you are a smoothie fan, as it is very easy to overdo the amount of fruit you have when making those.

Let’s discuss a meal example – from a FODMAP stacking perspective, can you do this to build a meal?

Can a meal include a:

Palm-sized piece of protein: e.g. chicken, fish, eggs, lamb, seafood, beef, firm tofu, tempeh
1/4 plate of carbohydrate: e.g. a slice of low FODMAP bread, gluten free pasta, rice, potato etc
2-3 low FODMAP servings of vegetables

Would this be okay in terms of FODMAP stacking?

Yes, it’s okay. We want you to avoid limiting as much food as possible. You can have at least three low FODMAP servings of vegetables in the same meal and be okay. We want you to get your five servings of vegetables in per day. We also want you to combine these vegetables along with a carbohydrate and protein into your meals. Just focus on using the low FODMAP serving sizes.

If someone is still having symptoms after several weeks on the low FODMAP diet, what should that person do next?

Start by recording what you are eating and what your symptoms are so you can look for any patterns. If possible, we always recommend working with a FODMAP-trained dietitian – we have a directory of FODMAP-trained dietitians on monashFODMAP.com. These dietitians have been trained in the FODMAP diet can help you make sense of what is going on. They can assess if stacking is the problem or if something else is happening.

Our top tip is not to try and do the low FODMAP diet by yourself. Work with a dietitian or reach out to one of the great online FODMAP communities on Facebook or on the Monash FODMAP Facebook page.

Got a question?

Feel free to leave us a comment and we’ll reply to you as soon as we can.

Extra Resources & Final Thoughts

You can support the amazing work Monash University does by downloading the Monash University FODMAP Diet App. The money you pay goes straight back into low FODMAP research.

You can also check out Monash University’s latest FODMAP stacking resource in their Monash Low FODMAP Cookbook. In the cookbook, you will find the ‘stacked cup’, a visual representation of the level of FODMAPs in each recipe and what recipes you can combine.

If you want more FODMAP resources, don’t forget to go and explore the Monash FODMAP website or the low FODMAP blog and low FODMAP recipe area on alittlebityummy.com.

We hope you’ve found this FODMAP chat session on FODMAP stacking useful and we look forward to chatting with you again soon.

Image credit: A Little Bit Yummy