The low FODMAP diet isn’t as easy as a food being categorised as high FODMAP or low FODMAP. Often a food will have low FODMAP, moderate FODMAP and high FODMAP serving sizes. That means even if a food is listed as low FODMAP, that doesn’t always mean you can eat unlimited quantities without triggering symptoms. This article aims to help you understand how low FODMAP serving sizes work, so you can reduce your FODMAP load faster and settle your gut symptoms.
Where do you find information on low FODMAP serving sizes?
The Monash University FODMAP Diet App contains the most up-to-date lists of low and high FODMAP foods, along with recommended serving sizes. This app is also updated every couple of months with new FODMAP information.
Just remember that every person has a different tolerance level to FODMAPs and the serving sizes in the app are conservative, so you might find you can tolerate a little bit more than the recommended serving size. During the FODMAP reintroduction phase, you’ll discover your individual tolerance level for each of the FODMAP groups.
How do you use the traffic light system in the Monash University FODMAP Diet app?
The Monash University FODMAP Diet App organises foods by a traffic light system based on the FODMAP levels for a typical serving size of that food per meal (1). Green is low FODMAP, amber is moderate FODMAP, and red is high FODMAP (1).
When you click on a food in the app, you can find out what FODMAPs are in the food, along with extra serving-size notes (1). You can eat any green-rated serving size for a food during the first phase of the low FODMAP diet (1). That means that if a food has an overall red rating (high FODMAP) but has a smaller green-rated serving size, you can still have the smaller serving size of that food during the first phase of the low FODMAP diet (4).
FODMAP Traffic Light Examples
Here are some examples to help you understand the Monash University traffic light system:
Avocado is rated high FODMAP overall. However, a small 60g (3 tablespoon) serving size is low FODMAP and can be enjoyed in the first phase of the diet (3).
Sweet potatoes are rated low FODMAP overall. However, this vegetable needs good portion control as it can quickly become high FODMAP. The low FODMAP serving size is 75g (1/2 cup) of sweet potato (this is the raw weight) and becomes moderate FODMAP at a 100g (2/3 cup) (3). It is very easy to accidentally eat a high FODMAP serving size of sweet potato once cooked, especially if it’s in a meal like sweet potato fries.
Quick oats are rated moderate FODMAP overall. They are only low FODMAP at a ¼ cup portion (dry measurement before cooking). If you eat a ½ cup portion (dry measurement before cooking), then you will consume moderate levels of FODMAPs (3).
While in the first low FODMAP phase of the diet focus on avoiding high FODMAP serving sizes of foods, limit moderate FODMAP serves, and focus on eating low FODMAP serving sizes of foods (1).
How many different low FODMAP foods can you have in each meal?
The Monash University FODMAP cut-off levels are conservative. This means you can eat multiple low FODMAP foods per meal, just make sure you stick to the recommended serving sizes (4).
What happens if you want to eat more than the recommended serving size for a low FODMAP food?
If you want to eat more than the recommended serving size for a low FODMAP food, check the additional information provided with each food listing in the Monash University FODMAP Diet App. Some low FODMAP foods will become high FODMAP at larger serving sizes, while other foods like carrots, potatoes and rice will remain low FODMAP to eat in larger serves (2 4).
