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Should you Weigh your FODMAP Portions?

May 13,2019



We know that FODMAPs are all about portion sizes. There are many foods that are low FODMAP at one serve, but become high FODMAP at a larger serve. These serve sizes are listed in the Monash app using green, yellow and red traffic lights for low, moderate and high FODMAP serve sizes.


If you’re just starting a low FODMAP diet, you probably have lots of questions (most people do!).  And one of the most common queries we hear is ‘Do I need to weigh everything, to make sure it’s a low FODMAP portion?’. Before we answer this question it’s important to have a little bit of background on FODMAP cut offs.


What you need to know:

  1. We can test foods in a laboratory, and measure which FODMAPs are present, and in what amount.This figure is then used to rate foods as low, moderate or high, according to the serving size.
  2. Research is used to estimate the dose of FODMAPs that a person with IBS will likely tolerate, without causing gut symptoms.


Using the two factors above, ‘Cut Off’ points have been set for each of the FODMAP groups. The important thing to understand here is that the cut offs are set at the point where 95% of people with IBS will tolerate that food or serve size. This means that people with IBS who are following a low FODMAP diet, can reasonably be expected to feel a lot better. Even if they’re super sensitive.


However! It also means that there is a larger serve size that 50% of peoplewill tolerateand an even larger serve that 25% of people will tolerate. In other words, these cut off points are very conservative.


One more thing:

It’s also important to factor in that measuring FODMAPs is not an exact science. This is because no two apples are going to be identical in weight, calories, vitamins or FODMAPs – even if they come from the same tree. There will absolutely be a degree of natural fluctuation from one apple to the next. Additionally, we also know that seasonal fluctuations and storage conditions can affect FODMAP content as well. FODMAP ratings listed in the Monash app are only ever an AVERAGE calculated across several samples of each food.


But, back to the question at hand! Do you need to weigh your food?

Depending who you ask, you might get a different answer.  But most dietitians would agree, that weighing or measuring every morsel of food you eat is simply not necessary. It can actually be counterproductive, causing more stress and anxiety (which indirectly worsens gut symptoms), or leading to disordered eating behaviours and rebound bingeing on restricted foods.


The FODMAP Elimination phase is solely about working out if you are FODMAP sensitive and if this diet is going to help you. In most cases, ball park is more than good enough. Reducing the big triggers you eat every day – like onion, garlic, wheat and dried fruit or juice – is usually more than enough to lower your FODMAP load considerably, and see great results. It’s actually not necessary to get the diet ‘perfect’ just to see results.


The Challenge phase, on the other hand, is all about finding out where you sit on the scale FODMAP sensitivity, so that you can personalise your diet in the long run and not over-restrict. Read more about the 3 phases of the FODMAP diet.


We recommend weighing (or measuring) in 3 situations:

  1. If you are wanting to eat a high FODMAP food that only has a very smalllow FODMAP serve (e.g. honey or apple) it’s probably best to measure this using a teaspoon or scales.
  2. If you have been doing low FODMAP for a while, and you’re not getting consistent results. In this case, you may want to weigh or measure some of your portions and double check if they are consistent with low FODMAP serves.
  3. If you are just starting out and you have absolutely no idea of what a reasonable serve should be. In this case, you may like to weigh or measure your usual portion as one off to get an idea.


Final thoughts:

FODMAPs work on a threshold basis.  We all have different sensitivities, but FODMAP cut-offs are very conservative. In our experience as dietitians, that extra blueberry, bite of celery or cup of tea is not going to push you over the limit, and derail the whole diet. While you on the initial Elimination phase it’s a good idea to take a step back and think about the bigger picture. Don’t let FODMAPs take over your every waking hour!


If you are struggling with what to eat, are not improving on the low FODMAP diet, or seem to not tolerate many low FODMAP foods, we recommend consulting a dietitian with expertise in food intolerance, for assessment and trouble-shooting advice.