FODMAP Reintroduction: A Test Plan for Phase 2
The FODMAP diet is not meant to cut out onions, wheat or pulses for good. After the strict elimination phase comes reintroduction. You test one FODMAP group after another and find out what you tolerate and in what amounts. This guide covers the process, a test plan with specific foods and amounts, and how to read your results.
Key points
- The FODMAP diet has three phases: elimination (2 to 6 weeks), reintroduction (usually 8 to 12 weeks) and a long-term, personalised diet.
- You only ever test one FODMAP group at a time, over three days with increasing amounts.
- Between two tests, you take a break of two to three days until any symptoms have settled.
- You test fructans separately for grains, onion and garlic, and polyols separately for sorbitol and mannitol.
The three phases of the FODMAP diet
1Elimination
2 to 6 weeks
You replace high FODMAP foods with low FODMAP ones. Our FODMAP list shows you which ones those are.
2Reintroduction
usually 8 to 12 weeks
You stay low FODMAP overall and test the individual groups one after another.
3Personalisation
long term
You eat everything you tolerate again and only limit what causes symptoms.
The timings come from the current information sheet by Monash University, which developed the approach. How long it takes you depends on how quickly your symptoms settle and how many groups you test.
Why reintroduction is worth it
Many people feel much better during the elimination phase and would happily stick with it. In the long run, though, a strict low FODMAP diet is more restrictive than it needs to be:
Most people only react to some of the FODMAP groups. They can eat everything else again.
Fructans and GOS feed beneficial gut bacteria. Studies show that a long, strict restriction can change the make-up of your gut flora.
Eating with friends, in restaurants or when travelling gets easier once you know your limits.
Afterwards you know which amounts work for you and no longer have to guess with every food.
When to start phase 2
Start testing once your symptoms have clearly improved during the elimination phase and have been stable for a few days. This is usually the case after 2 to 6 weeks.
If nothing has changed after six weeks, there is little point in simply carrying on with the diet. In that case, your symptoms may have a different cause.
How a test works
Choose one group. You only ever test one FODMAP group, using a food that contains, as far as possible, only that group.
Three days, increasing amounts. On day 1 you eat a small portion, on day 2 twice as much and on day 3 three times as much, ideally at the same time of day.
Stay low FODMAP otherwise. All your other meals stay low FODMAP during the test. That is the only way to get a clear result.
Write everything down. Note what you ate and when, and how you felt afterwards. You can do this on paper or in the diary in the Monash FODMAP app.
Take a break. After each test, go back to a strict low FODMAP diet for two to three days until any symptoms have settled. Only then move on to the next group.
Tip: Plan your tests for quiet weeks. Eating out, a lot of stress or more coffee and alcohol than usual can easily distort the results.
Test plan: foods for each FODMAP group
Each of the following test foods contains mainly one FODMAP group. The amounts are for day 1. On day 2 you eat twice as much, on day 3 three times as much.
| FODMAP group | Test food | Starting amount on day 1 |
|---|---|---|
| Lactose | Cow’s milk or yoghurt | 125 ml milk or 125 g yoghurt |
| Fructose | Mango, or alternatively asparagus or orange juice | ¼ mango |
| Sorbitol | Fresh apricots or cherries | See the Monash app |
| Mannitol | Celery, or alternatively portobello mushrooms or sauerkraut | ¼ celery stick |
| Fructans (grains) | Wheat pasta or wheat couscous | 5 tbsp cooked pasta |
| Fructans (onion) | Onion, cooked | 1 tbsp |
| Fructans (garlic) | Garlic, raw or cooked | ¼ clove |
| GOS | Canned beans or silken tofu | 2 tbsp beans |
Test foods based on Monash University’s 2025 update, starting amounts based on the Gloucestershire Hospitals information sheet (NHS, 2023). Where no amount is given, you will find the current portion size in the Monash FODMAP app.
Test sorbitol and mannitol separately, and do the same for fructans from grains, onion and garlic. Foods with several FODMAPs, such as apples, pears or chickpeas, come last, once you know how you react to the individual groups. You can test the groups in any order you like.
How to read your results
You tolerate this group well and can bring these foods back into your meals once all the tests are done. For fructans, this only applies to the source you tested.
Small to medium amounts are probably fine, large portions less so.
Stop the test and wait until you feel well again. Later you can test the group again with a smaller amount.
Symptoms during a test do not harm your gut. They just show you where your personal limit lies.
FODMAPs add up within a meal. Three small portions that are fine on their own can be too much together. We explain this in our article on FODMAP stacking.
Phase 3: your personal diet
Once the tests are done, bring all the foods you tolerated well back into your regular diet. Limit the groups you reacted to only as much as you need to. Often it is enough to keep the portion small or not to combine the food with other FODMAP sources.
Your tolerance can change over time. So after a few months, it is worth retesting foods that did not agree with you.
Enzymes as an add-on: FODZYME
Many people know digestive enzymes from lactase tablets for lactose intolerance. There are now enzymes for other FODMAP groups as well.
FODZYME is an enzyme powder that you sprinkle over your food or mix into it. It comes as a Home Kit for use at home and as an On-the-go Kit with single-serve sachets. It contains three enzymes: a fructan hydrolase for fructans, alpha-galactosidase for GOS and lactase for lactose. According to the manufacturer, they break down these FODMAPs while they are still in the food. FODZYME does not work on polyols such as sorbitol and mannitol, or on free fructose.
For reintroduction, the rule is: test the FODMAP groups without enzymes first. Otherwise you cannot see how your body reacts on its own. Once the tests are over, FODZYME can be handy in everyday life, for example in a restaurant when you cannot tell how much onion or garlic is in a dish.
Breaking down fructans produces fructose. FODZYME is therefore not suitable if you have hereditary fructose intolerance. You will find more answers in our FODZYME FAQ.
How to use FODZYME
- Sprinkle ¼ tsp (0.75 g) over your food or mix it in shortly before eating. One sachet from the On-the-go Kit contains 1 g.
- Do not cook with it: above 60 °C the enzymes stop working.
- Drinks that contain FODMAPs, such as milk, work too. Do not add the powder to plain water.
- For large meals, or if the meal lasts longer than 30 minutes, take a second portion.
FODZYME Home Kit60 servings for use at home
FODZYME On-the-go Kit30 servings in sachets for eating out
Frequently asked questions about reintroduction
How long does reintroduction take?
Allow about 8 to 12 weeks. Each test takes three days, plus the breaks in between. With eight test foods, that keeps you busy for at least six to seven weeks.
In what order should I test the groups?
You can choose the order freely. Many people start with the foods they miss most in everyday life, such as wheat bread or milk.
What if I react to almost everything?
Sometimes the test amounts are too large, or other factors such as stress play a part. Repeating the test with smaller amounts often gives you a clearer picture.
Can I use enzymes during the tests?
Better not. Enzymes change the FODMAP content of the meal and therefore the test result. Only use them once you know your limits.
Sources: Monash University, The 3-step FODMAP Diet (2026) · Monash University, Practical tips for FODMAP reintroduction · Monash University, Reintroduction update (2025) · Gloucestershire Hospitals NHS, FODMAP reintroduction (2023) · FODZYME, Dosing guide
Photo: Cathryn Lavery on Unsplash
