Low FODMAP serving sizes:
why the same food can be low and high

Very few foods on the low FODMAP diet are completely off-limits. What often matters is the portion. A food that triggers symptoms at a larger serving may be better tolerated at a smaller, low FODMAP serving. That's because FODMAP content is dose-dependent, and individual tolerance varies. So instead of simply asking "Can I eat this?", it's often more useful to ask "How much can I eat, and what other FODMAPs am I having with it?"

One food, three answers

Foods are tested in a lab and published as serving sizes, with a traffic light attached. Green is a serve that is low in FODMAPs and fits the strict phase. Amber indicates a serve containing moderate amounts of FODMAPs, while red indicates a serve that is high in FODMAPs. That is the idea behind Monash University and its published research, and it is why a list of "foods to avoid" with no grams on it is close to useless.

Stacking is worth keeping in mind

Two portions that are low FODMAP on their own can sometimes add up when eaten together. This is often referred to as FODMAP stacking.

This is particularly relevant when several foods containing the same FODMAP group are combined in one meal. For example, several individually low servings of fructan-containing foods may contribute a larger overall fructan load.

That doesn't mean you need to calculate every FODMAP in every meal. Individual tolerance varies, and the goal of the low FODMAP diet is not to make eating more restrictive than necessary.

If you notice symptoms after a meal made entirely from low FODMAP servings, look at the meal as a whole. Portion sizes and combinations may matter, especially when several foods contribute the same FODMAP group.

Low FODMAP serving sizes are a starting point

Published low FODMAP serving sizes are useful guides, especially during the elimination phase, but they are not lifelong limits.

Your own tolerance may be different. The reintroduction phase is designed to help you understand which FODMAPs you tolerate and in what amounts, so you can build a diet that is as varied as possible.

Weigh first, then learn to eyeball

You don't need to weigh every ingredient forever. When you're getting familiar with low FODMAP serving sizes, weighing foods occasionally can help you understand what those portions actually look like on your plate.

Over time, it becomes easier to estimate the portions of foods you eat regularly without reaching for the scales every time.

In Belly Buddy, ingredients saved to your My FODMAPs list show low FODMAP serving information alongside their rating, so you can easily check portions when you need them.

The same food can have a different FODMAP rating depending on how much you eat, which is why portion information matters just as much as the ingredient itself.

Belly Buddy uses FODMAP information informed by publicly available scientific research, including research from Monash University, and is not affiliated with or endorsed by Monash University. You can learn more about how our ratings work on our How We Rate page, and find portion information throughout our food aisles.

New to the low FODMAP diet? Start with our What Are FODMAPs? guide before diving into serving sizes.

And remember: the elimination phase of the low FODMAP diet is designed to be temporary and should be followed by reintroduction and personalisation. Working with a FODMAP-trained dietitian can help you identify your individual tolerances while keeping your diet as varied as possible.