Why is portion control so important on the Low FODMAP diet?
Portion sizes are crucial to getting good symptom control while on the low FODMAP diet. Just because a food is classed as low FODMAP it doesn’t mean you can eat unlimited quantities. Also, some high FODMAP foods are safe in small portion sizes. The goal of the low FODMAP diet is to reduce the overall level of FODMAPs to help you gain good symptom control, and it is not a FODMAP free diet (1).
Where do you find information on low FODMAP portion sizes?
The Monash Univeristy Low FODMAP Diet app or Monash University Low FODMAP booklet, both contain up-to-date lists of low FODMAP foods, and recommended safe serving sizes.
The recommended serving sizes are a great place to start. Just remember that every person has different tolerance levels to FODMAPs, which may mean you can tolerate a little bit more or less than the recommended serving size (1 2). You will need to find your own tolerance levels.
How do you use the traffic light system in the Monash University app?
The Monash Low 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, orange is moderate FODMAP, and red is high FODMAP (1). You need to click on each food in the app to find out what the recommended serving size is. Make sure you read the notes under the suggested serving size, as some low FODMAP foods become high FODMAP if you go over the recommended portion (1). It is also important to explore red rated foods as some of them do have a smaller low FODMAP serving size (1).
For example:
Sweet potatoes are high FODMAP if you have 3/4 cup (112g). However, a smaller serving of ½ cup or 75g is considered low FODMAP (3).
Quick oats are only low FODMAP at a ¼ cup portion (dry measurement before cooking). If you consume a ½ cup portion (dry measurement before cooking) then you will consume moderate levels of FODMAPs (3).
Broccoli is considered low FODMAP at ½ cup to 1 cup serves, depending on which part of the broccoli you are eating. However, notes in the app tell us that larger serves can become high FODMAP (3).
While in the first phase of the diet, it is recommended that you avoid red rated serving sizes of foods, limit orange rated serves, and focus on eating mainly green rated serving sizes and foods (1).
How many different low FODMAP foods can you have in each meal?
The low FODMAP recommended serving sizes have been developed based on typical serving sizes of that particular food per meal (1). This means you can eat a number of different green rated foods per meal, just make sure you stick to the recommended serving sizes (1). So if you are feeling hungry, add another green rated vegetable to your meal. I recommend weighing your low FODMAP vegetables and fruit before cooking, to make sure you are staying within the recommended serving sizes.
If you want to eat more than the recommended serving size for a low FODMAP food then you need to check the additional information provided with each food listing. Some low FODMAP foods will become high FODMAP at larger serving sizes, while others will remain safe to eat in bigger serves (1 2).
For example, registered dietitian Kate Scarlata recommends adding a few more bites of rice or white potatoes if you are feeling hungry as these foods are very low FODMAP (2).
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 serve, you should be okay to eat the same food a couple of times a day (2).
Do meats and other sources of protein contain FODMAPs?
Chicken, fish, red meat, and eggs are protein based foods that are FODMAP free (3 2). This means if you are feeling especially hungry you can eat slightly larger portions of these naturally FODMAP free foods (2).
What are the portion control rules around fruit?
According to Dr. Sue Shepherd (the creator of the low FODMAP diet), you should not eat more than one serve of ‘suitable’ fruits per meal or sitting (4). One serve normally equals about one metric cup of cut up fruit, or one whole piece of fruit, such as one medium banana or medium orange (3 4). You can enjoy several serves of fruit per day as you like – but leave two to three hours between each serve (4).
Final Thoughts
The Monash Univeristy Low FODMAP Diet app is a great resource for low FODMAP serving sizes. Make sure you explore each food to find the recommended serving. You can eat multiple green rated foods for each meal and you can repeat the same foods throughout the day. If you are repeating foods leave a few hours in between each serve. When it comes to fruit, remember to have one serve at a time and leave 2 to 3 hours between each serve. If you need guidance, make sure you consult a FODMAP trained dietitian to help you find your tolerance levels. For more helpful tips you can follow us on Facebook or sign up for our weekly newsletter. Happy Eating!
Alycia says
September 2, 2018 at 9:29 pmI was just wondering if the lowfodmap serving of sweet potato (1/2 a cup) is the dry weight or the weight after cooking?
Alana Scott says
September 5, 2018 at 7:06 amHi 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 🙂
Brittney says
October 8, 2018 at 4:16 amCan 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 !
Alana Scott says
October 8, 2018 at 10:19 pmHi 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?
Isabelle says
August 2, 2019 at 3:55 pmHello 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?)
Alana Scott says
August 4, 2019 at 8:56 pmHi 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.
Katarina Kovacevic says
September 25, 2019 at 1:48 pmHow big should our meal sizes be? So is it better to consume smaller meals rather than really large ones on the FODMAP diet?
Alana Scott says
September 25, 2019 at 6:44 pmHi 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.
Sharon says
November 14, 2019 at 7:35 pmI’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!
Alana Scott says
November 18, 2019 at 7:07 amHi 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.
Chloe says
April 20, 2020 at 3:58 amHi Alana,
Thanks for the info above! Just a quick question that I hope makes sense and I think an example would be best to try to get my point across.. today I wanted to make a sort of potato salad but I wasn’t sure if you can have the Monash recommended amount of potato (75g) and sweet potato (75g) at the same time and then for the sauce the recommended mayo amount (2 TBSP) and sour cream amount (2TBSP) at the same time? Hope this makes sense.
Thanks Chloe
Alana Scott says
April 20, 2020 at 8:03 amHi Chloe,
Thanks for the great question. Yes you can combine those ingredients. Both sweet potato and sour cream become high FODMAP at larger serves, but if you look at the notes they contain different FODMAP groups. Sour cream has lactose and sweet potato has mannitol. This means if you combine the low FODMAP serving sizes of those foods in the same meal you won’t go over the FODMAP threshold for either of those FODMAP groups.
Just avoid combining two serves that contain mannitol or two serves that contain lactose (eg a low FODMAP serve of cream + a low FODMAP serve of sour cream) in the same meal as that would add up to a high FODMAP serve. Does that make sense?
Georgina says
May 16, 2020 at 1:21 pmIs there a safe low fodmap portion size for dates, and apple? Being allowed a nibble would keep me happy!
Alana Scott says
May 23, 2020 at 9:02 pmHi Georgina,
That is a great question. Both have super small low FODMAP serving sizes. For dates it’s 8g (1/3 of a date) and for apple it’s 20g (about 2 small slices). We would highly recommend you get the Monash University Low FODMAP Diet app so you have up to date information on portion sizes.