Low-FODMAP reintroduction: how to test one group at a time
How the reintroduction phase of the low-FODMAP diet works: which groups to test, how to raise the portion over three days, when to stop, and how to record what you learn.
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Short answer
After two to six weeks of low-FODMAP eating, you bring FODMAPs back one group at a time: one test food, a rising portion over three days, the rest of your diet still low-FODMAP. You stop a test if symptoms become significant and wait until they settle before the next group. The goal is the most varied diet your gut tolerates, ideally with a dietitian.
Choose this if
A paper diary works if you test one group at a time and write every meal and symptom down.
Choose the other option if
Gutli helps when you want each challenge, dose and symptom recorded in one place and ready for your dietitian.
At a glance
| Feature | Paper diary | Gutli |
|---|---|---|
| Records food, portion and time | Yesby hand | Yeswith portion reference |
| Tracks one FODMAP group per challenge | Partlyif you keep it tidy | Yesfood, dose, duration and response |
| Symptoms with the Bristol chart | Partly | Yes |
| Shows elimination, reintroduction and maintenance | No | Yesphases you control |
| Report for your dietitian | Noyou bring the notebook | YesPDF and CSV |
| Stays private | Yes | Yeson your iPhone only |
Where reintroduction fits
The Monash University low-FODMAP diet has three steps. First, a strict low-FODMAP phase, which Monash recommends trying for two to six weeks followed by a review. Second, reintroduction, where you find out which FODMAPs trigger your symptoms and how much you tolerate. Third, a personal long-term diet that brings back everything you can handle.
Staying on the strict phase for months is not the goal. Many high-FODMAP foods are good for the gut bacteria, and a diet that is more restricted than it needs to be is harder to live with.
The groups you test
FODMAPs are grouped by type, and each group is tested with a food that contains mostly that one group.
- Fructose, for example honey or mango.
- Lactose, for example milk or yogurt.
- Fructans, for example wheat bread, garlic or onion.
- Galacto-oligosaccharides (GOS), for example lentils or chickpeas.
- Polyols: sorbitol (for example blackberries or avocado) and mannitol (for example mushrooms), tested separately.
A three-day challenge
Pick one test food and eat it on three days in a row, with a small portion on the first day, a medium one on the second and a normal portion on the third. Everything else you eat stays low-FODMAP, so a reaction can only come from the test.
Write down what you ate, how much and when, and how you felt over the following hours. If symptoms become significant, stop the test: you have found your threshold for that group.
Before the next group, wait until your symptoms are back to your usual baseline. Monash suggests a few days between challenges, and longer if symptoms linger.
Reading the results
No symptoms at a normal portion means you likely tolerate that group, and it can come back into your meals. Symptoms at a small portion mean you are sensitive to it; symptoms only at the largest portion mean you tolerate a moderate amount.
Tolerance can change over time, so a group that failed once can be tested again months later. A registered dietitian trained in the diet can help you choose test foods and read unclear results.
Frequently asked questions
How long should the elimination phase last before reintroduction?
Monash recommends trying the low-FODMAP diet for two to six weeks, then reviewing it, before moving on to reintroduction.
How long does each FODMAP challenge take?
Three days of rising portions of one test food, then a few days back on your usual low-FODMAP meals before the next group, longer if symptoms linger.
What if I react during a challenge?
Stop that test, return to low-FODMAP eating until you feel back to normal, and note the portion that caused symptoms. That is your threshold for now.
Can I test two FODMAP groups at once?
It is not recommended: if you react, you cannot tell which group caused it. Test one group at a time.
Is Gutli available?
Gutli is in development for iPhone.
Our pick
Gutli, a food and symptom journal for low-FODMAP
Gutli is built for the reintroduction phase: each challenge records the food, dose, duration and your response, next to your symptoms and the Bristol chart, in a report your dietitian can read.
- One FODMAP group at a time, with food, dose and response
- Meals and symptoms with the Bristol chart
- PDF and CSV reports for your clinician
