How FODMAPs Add Up


Still not feeling great, even though you’re following the diet SO WELL? One of the reasons could be that FODMAPs add up.

Last week, we talked about how it’s not as simple as a food either being high or low FODMAP (check it out here). Foods are classified as high or low FODMAP based on standard serving sizes. This means portion sizes are so important with the low FODMAP diet and could be the reason why you’re still getting symptoms even though you’re sticking to ‘low FODMAP’ foods. Another reason could be the total FODMAP load that you’re eating in each meal, and throughout the entire day.

One thing I’ve learnt, both from studying the diet, and from personal experience, is that FODMAPs add up. Even once you’ve taken portion size into account (which is a hurdle in itself!), you might struggle. You might eat ‘green’ (low FODMAP) servings of 5 different foods at lunch that all contain a small amount of FODMAPs, but are still classed as ‘green’ as they’re below that threshold we talked about last week. So, you’re being really good and following the diet, BUT…you might still feel super bloated after that meal. This could be because your total FODMAP load for the day or the meal is actually quite high. I'll explain why..



When Monash set the low FODMAP limits on individual foods, it was done quite conservatively. This was to allow us to have more than one serving of ‘green’ (low FODMAP) foods at each meal. Although they were set conservatively, we still may not be able to eat an unlimited amount of ‘green’ servings in one meal, or throughout the day, without any reaction from our gut.

They set a limit of 0.5g total FODMAPs (excluding lactose) per meal, which is considered the tolerable amount. This is actually not that high!

To put this into context, the cut off level for a food containing fructans (one of the FODMAP sub-groups) is 0.20g. This means that if a standard serving size of food has more than 0.20g of fructans in it, it’s classed as ‘high FODMAP.’ However, anything less than that, e.g. 0.19g, and it would be low FODMAP. This made my brain explode a little bit when I tried to understand it, so let me use a real example. A standard serving size of zucchini/courgette has 0.19g of fructans. This is below the cut off of 0.20g so it’s classed as low FODMAP.

So, if you had 3 servings of foods with 0.19g fructans in your lunch, you’d be having a total of 0.57g fructans, which is above that 0.50g limit for a ‘tolerable’ amount in one meal. This also applies if you’re having a combination of fodmaps, e.g. fructans and sorbitol..whenever the total FODMAP load goes above that 0.5g limit. This is really easily done in meals such as minestrone soup (fructans from onion + garlic and GOS from legumes).



There is actually limited evidence to show what the effect is of FODMAPs adding up. There’s no guarantee that, if you eat more than the 0.5g limit of FODMAPs in one meal, you’ll get symptoms. This is just a guideline that has been set up and everyone will have a completely different tolerance level. This is so personal, just like the rest of the diet.

On top of this, Monash haven’t set a limit for total FODMAPs per day. They stopped at one meal. This means there’s really no evidence to show what happens when FODMAPs add up throughout the day.

I wanted to talk about this so that you’re aware of it as an answer to why you could still be getting symptoms even though you’re following the diet perfectly. However, it’s not another thing to start worrying about.





Like I said, this is just something to be aware of, not something to stress about. You do not have the time to be looking up the exact FODMAP quantity in every food you eat and calculating whether it’s over the limit. You’d never actually get round to eating your food! There is NO WAY anyone has time for that.



I’d just keep this information in mind if you’re experiencing a flare up and can’t work out why. If you’re frustrated because you’ve been following the diet so well, but still had to run to the toilet after dinner or were super bloated after lunch, this could explain it. If you do get symptoms, and can’t put it down to anything else, consider whether this could be the cause. I know the thing I found the worst was just not knowing why my stomach had bloated up. At least if you know this could be why, you can note it down, see it as a learning experience and move on.



Long term, the aim of the diet is for you to be eating as much of a variety of foods as possible. So I’d never advise limiting what you eat more than you need to. However, for the first couple of weeks of the elimination phase, it might make your life a lot easier to stick to foods that are totally FODMAP free, rather than having ‘green’ serves of food containing FODMAPs.

For example, no trace of FODMAPs have been found in oranges. Therefore, you’d be better off with an orange than 16g of apricot (which is a ‘green’ serve but apricots still contain FODMAPs). You’ll already have so much to think about in the first few weeks of the diet. So, it might make your life so much easier not to have to worry about serving sizes and the fact that FODMAPs add up. When you get more confident in the diet, you can start to introduce them.



As you can see, the low FODMAP diet is complicated. It’s also very individual. That 0.5g total FODMAP limit was set by Monash based on what’s been found to be a tolerable amount of FODMAPs for most people. However, everybody’s individual limit will be completely different. You need to find yours. A lot of trial and error will be involved in discovering your personal tolerance limit.

This is hard and takes a lot of time and energy. If you want guidance and support through this, I’d really recommend getting some help from someone trained in the low FODMAP diet. Don’t waste hours of your time (that you don’t have!) trying to figure all of this out yourself. Consider getting someone’s help to guide you through working out your personal limits.


  • FODMAPs add up and this could be why you’re still feeling terrible even though you’re sticking to the diet perfectly.

  • Monash have set a limit of total FODMAPs that are considered ‘tolerable’ in one meal.

  • Going over this limit of total FODMAPs in one meal could be causing you symptoms.

  • However, there’s no guarantee you’ll experience symptoms by exceeding this limit, as everyone’s limit will be so personal.

  • What you should do about it:

    1. Don’t stress - nobody has time to calculate all of this

    2. Be aware - just keep this in mind as a possible explanation when you’re experiencing a flare up and can't work out why

    3. Stick with FODMAP free foods - this may make your life easier when you’re first starting the diet

    4. Get support - save your time and energy and get someone FODMAP qualified to guide you through all of this

Thanks so much for taking the time to read this. Have you noticed the effects of FODMAPs adding up? Let me know in the comments.

Sophie x

Sophie BibbsComment