How to avoid FODMAP stacking

stacking fruit

Erin Dwyer, Lyndal McNamara & Dr. Jane Varney - Research Dietitians, 17 April 2019

Recently we have received a lot of questions regarding ‘FODMAP Stacking’. FODMAP stacking is a term referring to how FODMAPs can ‘add up’ in our gut before they cause symptoms. The most common question we get is how many ‘green’ foods can a person eat before the FODMAPs stack and the overall FODMAP content of a meal becomes too high.


Firstly, it is important to remember that if your symptoms are well controlled and you haven’t been thinking about FODMAP stacking, then don’t start worrying! FODMAP stacking is only something you want to consider if you notice that a low FODMAP diet has improved most of your symptoms, but you still experience some symptoms even though you are only eating low FODMAP foods. 


To explain stacking, let’s think about the digestive system. Bowel transit studies have found that in a ‘healthy’ individual it typically takes 12 - 48 hours for food to move from the mouth to the anus. FODMAPs induce symptoms when the food gets to the large bowel as that is where they ferment, so if we are eating lots of low FODMAP foods regularly (e.g. every 1-2 hours) it is possible for them build up in your large bowel and cause symptoms before they are excreted. 


It is very difficult to develop specific ‘rules’ about FODMAP stacking as every person with IBS has a varying level of tolerance to different types of FODMAPs. To avoid unnecessarily over complicating things, here are our top tips to help you avoid FODMAP stacking! 


Top tips to avoid FODMAP stacking:

1. Space out your meals - the best way to prevent any additive effect of FODMAPs is to leave 3-4 hours between your low FODMAP meals and snacks. If you find yourself peckish in between, refer to tip no. 2!

2. Eat more FODMAP free foods - you don’t need to worry about stacking when eating foods that are ‘FODMAP free’ i.e. no upper limit safe serve is provided. There are a LARGE NUMBER of foods included in the Monash App that contain little or no FODMAPs, even when consumed in large quantities. Examples of ‘FODMAP free foods’ include rice, strawberries and carrots. These can be identified by scrolling through the food guide and looking for foods with only one green traffic light (see example below). (Note: some foods with only one green light will have an upper limit but they are usually very very large and this quantity is unlikely to be eaten e.g. Kohlrabi is 600g!).

stacking ex

3. Avoid having too much fruit, especially in the same meal - This is because many fruits contain multiple different types of FODMAPs, so stacking is more likely. Try to stick to 1 green serve of fruit per sitting and limit your overall fruit intake to 2 serves per day (as per healthy eating guidelines). If you want to include more than 2 serves of fruit in your diet, consider having FODMAP free fruits like strawberries, mandarins, oranges, grapes or paw paw. 

4. Focus on variety - A key recommendation in the Australian guide to healthy eating is variation. It is easy to avoid FODMAP stacking by eating a variety of different foods and not the same meal or foods over and over again. For example, choose three or more different types of vegetables in a green serving size to include at dinner every day, and if you think that stacking is an issue for you, consider including one or more FODMAP free varieties of vegetable as a base (see point 2!). Remember, protein foods like plain meat, chicken, fish and eggs are also naturally FODMAP free.

5. Don’t panic - Don’t worry if you eat a larger amount than the green serve listed accidentally, it won’t undo all your good work. If you do experience symptoms – look after yourself, implement some self care activities and start afresh tomorrow. Check out these blogs for ideas: Alleviate bloating OR Alleviate Constipation 

6. Lactose is not included in stacking - Lactose is digested differently to other FODMAPs and is only a concern for people with IBS who also have lactose intolerance. If you do have lactose intolerance, stick to the green serves of lactose containing foods listed in the app and stacking will not be an issue. 

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