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).
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Can you eat the same food multiple times in a day?
Providing you stick to the recommended low FODMAP serving size and leave a few hours between each serving, you can eat the same food a couple of times a day.
Do meats and other sources of protein contain FODMAPs?
Chicken, fish, red meat, and eggs are protein-based foods that are FODMAP free (2 3 4). Therefore, if you are feeling especially hungry you can eat a larger serving size of these naturally FODMAP free foods.
What are the serving size guidelines around fruit?
The general guidelines recommend enjoying one serving of low FODMAP fruit per meal (2). You can still enjoy several servings of fruit per day as long as you leave two to three hours between each serving. Check out our article to learn about fruit and the low FODMAP diet.
Final Thoughts
Understanding low FODMAP serving sizes can help you reduce your gut symptoms faster while on the low FODMAP diet. The Monash University FODMAP Diet App is the best resource for low and high FODMAP food and serving size information to help you on your journey. Just remember you can eat multiple low FODMAP foods for each meal and repeat the same foods throughout the day, providing you leave a few hours between each serving.
Image credit: Alana Scott
References:
- McNamara, L. Understanding the traffic lights in the Monash FODMAP Diet App. Monash University FODMAP website. October, 2018. Retrieved from https://monashfodmap.com/blog/traffic-light-system/ Retrieved on: 25-02-2023
- Dwyer, E., McNamara, L. & Varney J. How to avoid FODMAP Stacking. Monash University FODMAP Website. April, 2019. Retrieved from: https://monashfodmap.com/blog/how-avoid-fodmap-stacking/ Retrieve on: 25-02-2023
- Monash University FODMAP Diet App. Food Guide. The Monash University Low FODMAP Diet App. 2023: Version 3.0.9 (435). Date retrieved: 2023-02-23. Retrieved from :http://www.med.monash.edu/cecs/gastro/fodmap/iphone-app.html. Accessed: 2023-02-23.
- Monash FODMAP Team. FODMAP Stacking Explained. Monash University FODMAP Website. October, 2022. Retrieved from https://monashfodmap.com/blog/fodmap-stacking-explained/ Retrieved on: 25-02-2023
I was just wondering if the lowfodmap serving of sweet potato (1/2 a cup) is the dry weight or the weight after cooking?
Hi Alycia,
The low FODMAP serving of sweet potato is 75g (1/2 cup). This is the raw weight so weigh it before you cook it 🙂
Can I have the 1/2 cup of sweet potatoes twice a day if I space out the meals three hours or so or does it mean 1/2 cup a day? I get confused with this part of it and portion sizes. Thanks !
Hi Brittney,
We know portion sizes can be confusing! In theory, leaving three hours between each serve is enough time to reduce FODMAP overload for many people. However, if you are feeling concerned then we would recommend having the first serve in the morning (eg fried sweet potato with your breakfast) and then again at dinner time. If you tolerate that well then you can start bringing the serves closer together. Does that help?
Hello Alana,
This explanation is of great help because portion and serving sizes always get me confused too and most often the more I think about it, the less I can figure it out!
However, as I’m a newbie there’s a point that’s still not quite clear to me…
Let’s take rice flakes for example; 1/2 serve is low in FODMAPs and so is 1 serve, does that mean there is no specific limit and rice flakes will remain low in FODMAPs regardless of the quantity?
(Or am I thinking too much?)
Hi Isabelle,
That is a great question. If there is no warning in the Monash Low FODMAP App in the notes area under the food, then it is generally considered safe to increase your serving size. As you increase your serve just monitor your symptoms to see if anything changes.
How big should our meal sizes be? So is it better to consume smaller meals rather than really large ones on the FODMAP diet?
Hi Katarina,
Thanks for leaving a comment. Sometimes FODMAPs can build up over the course of a meal so we would recommend avoiding excessively large meals. If you are sticking to healthy eating guidelines in terms of meal size and focusing on low FODMAP foods then you will be just fine.
I’m struggling knowing how to adjust flour to keep them my IBS symptoms in control. One piece of bread for breakfast seems to be fine, but 2 pieces definitely causes symptoms as the app says. But how does that adjust as far as if I chose a mini muffin instead, being that all other ingredients are in the green zone? Or if we have a birthday celebration, and I haven’t had any other flour, would a piece of cake irritate my symptoms and how would I know how much I would be able to tolerate? Is it just trial and error? Thank you!
Hi Sharon,
Unfortunately figuring out what you tolerate when it comes to wheat flour is a bit of trial and error. It is possible that a small muffin or piece of cake might be within low FODMAP limits for wheat but we won’t know unless they are laboratory tested.
So our suggestion is once your symptoms are settled to test your tolerance level to the sweet treats and go from there. I hope that helps a little bit! If you have more questions, just let me know.
THANKYOU for this amazing explanation! please tell if one can have orange+guava( both according to their serving sizes) together in one meal? can i combine other 2 or 3 fruits too? Of course in their recommended serving sizes.
Hi Dhwani,
During the first phase of the low FODMAP diet we recommend that you limit your fruit intake to one portion/serve per meal and then leave 2 to 3 hours between each serve. If you want to combine two different fruits in a meal then try having a 1/2 serve of each so this would be 1 medium ripe guava and 1/2 an orange.
okay. Thanks 🙂
So you mean to say, even if we take the recommended low FODMAP serving size of cream and sour cream in one meal, because of the quantity that is increased now the lactose will be increased?
Hi Dhwani,
Thanks for commenting. That is correct – if you are using regular cream and sour cream (instead of lactose free versions) then the lactose from those two products will stack. Depending on how much of these products you eat in one meal you might end up with a moderate or high amount of lactose.
Hi,
I wanted to ask how much protein, carbs, fat and sugar is allowed per day while on low fodmap? I know over all calories per day should be about 1500 but I’m not sure how much of that should be from fat carbs and protein. I’m struggling to keep up with my fat intake. I’m very sensitive to all nuts even in low fodmap portion.
Hi Aneela,
Thanks for commenting. On the low FODMAP diet there isn’t a target for the amount of protein, carbs, fat and sugar allowed per day. Instead, it’s just recommended that you follow a healthy plate model – 1/4 plate protein, 1/4 plate carbohydrate (e.g. potato, rice, gluten free pasta), 1/2 a plate vegetables. Additionally, you should be aiming for a couple of handfuls of fruit and a couple of servings of dairy per day (there are low FODMAP options for both of these). It sounds like you might need some personalised nutrition advice so we would encourage you to reach out to a dietitian who can tailor your diet to meet your needs.
Hey I am new to Fodmap. I went through rectal cancer surgery and have no rectum. My GI Dr put me on Fodmap to see if the low fodmap foods would help my digestive system. I don’t know if I have IBS. All this is new to me what would you suggest in all this
Hi Shannon,
We are sorry to hear you have had such a challenging time. Due to your complex medical history, we would recommend working one-on-one with a dietitian who specialises in the low FODMAP diet and gut issues. They will be able to tailor the diet to your unique needs.