FODMAP Reintroduction Protocol: A 6-8 Week Challenge Schedule

Michael Eisenwasser 8 min read

Once the elimination phase has calmed your symptoms, the next job is figuring out which FODMAPs you actually react to. That's reintroduction, and it's the part of the diet where most of the useful information lives. The elimination phase tells you FODMAPs as a category matter. Reintroduction tells you which specific groups, at which doses.

The companion post how to track the FODMAP reintroduction phase covers what to write down during a challenge: foods, doses, symptoms, timing, and the confounders that blur results. This post covers the other half of the problem: when to test what, in what order, and how to sequence it all over 6 to 8 weeks without tripping over yourself.

A caveat before the schedule. There is no single universal protocol. Monash explicitly says "there is no particular rule to the order of FODMAPs to reintroduce," and the specific test foods and gram amounts vary by dietitian. What follows is a standard 8-week template that maps to how FODMAP-trained dietitians commonly sequence challenges. Use it as a starting frame, not as gospel.

The structure every challenge follows

Each FODMAP subgroup gets its own week. Within a week, the pattern is the same:

• 3 challenge days with the dose climbing each day.
• 2 washout days of strict low-FODMAP eating to let symptoms clear before the next challenge.

Symptoms can show up hours after the test food or the next morning, so a 2-day washout is the minimum. Some people need a third day. If you're still off on day 5, wait. Starting the next challenge while the last one is still rumbling contaminates your results.

On challenge days, the background diet stays low-FODMAP. The only variable that changes is the test food. That's what makes the experiment readable.

Exact gram targets for each test food live in the Monash FODMAP app under its reintroduction section. Use those rather than eyeballing "half a clove" or "a splash" of milk. The table below describes the general escalation pattern and which food to use for each subgroup; the actual dose on each day should come from the Monash app.

The 8-week schedule

The table below is a standard order that works for most people. Fructans technically counts as one subgroup under the Monash classification, but it gets split into two challenge weeks here (wheat vs. onion or garlic) because people tolerate those sources very differently. Week 8 is held as a buffer for any challenge that got interrupted, any ambiguous result you want to retest, or catch-up if life got in the way.

The pattern that matters is small → moderate → your normal serve. Pull the actual gram amounts from the Monash FODMAP app's reintroduction section; don't guess by the spoon, slice, or cup.

If garlic is a key food in your kitchen, run it as its own week instead of (or in addition to) onion. Garlic and onion are both fructan sources, but they're eaten in very different amounts and many people tolerate one but not the other. Run one food per week, not both together, so the result is attributable.

Why this order

There's no required sequence, but this one has a few things going for it.

Fructose and lactose come first. Both have single, well-characterized test foods. Starting here builds rhythm and often delivers an early pass, which is psychologically useful for a process that drags on for two months.

Polyols split into two weeks, not one. Sorbitol and mannitol are different molecules and different foods. Tolerance to one does not predict tolerance to the other. Running them in consecutive weeks keeps them separated cleanly. See is avocado low FODMAP for what sorbitol stacking actually looks like on a plate.

Fructans get at least two weeks. Wheat fructans, onion, and garlic all contain fructans, but real-world data shows people tolerate them very differently. Wheat bread passes for many people; onion and garlic fail for a much larger share. Running wheat separately from onion, and ideally garlic separately from both, gives you usable detail instead of a blanket "fructans fail" verdict. Splitting garlic and onion into two weeks of their own (see is garlic low FODMAP and is onion low FODMAP) pushes the schedule closer to 9 weeks, which is fine if you have the patience.

GOS goes near the end. Legumes take preparation and their reactions can be slower. Putting them late means you've built up experience reading your own signals by then.

Week 8 is a buffer. Something always goes sideways. A stomach bug, a trip, an unambiguously bad result you want to retest at a lower dose. The buffer prevents you from rushing and contaminating the last couple of challenges.

When to change the order

The order above is a default, not a prescription. Three reasons to reshuffle:

1. Start with what you miss most. Monash suggests one valid strategy is leading with the subgroup you'd most want back. If coffee with milk is what you've been grieving, move lactose to week 1. A pass there has the biggest quality-of-life payoff.
2. Start with what you suspect. If you already have a strong hunch that garlic or onion is your villain, testing it early gives you clear information faster.
3. Work around your schedule. Don't run a challenge during a stressful work week, travel, or your period. Push it to the buffer week and slot in a simpler challenge instead. Testing under noisy conditions produces noisy results.

The one order rule that's non-negotiable: one FODMAP subgroup at a time, never two in the same week.

What "pass" and "fail" actually mean

At the end of each challenge week, you're making one of three calls:

• Pass. Three days of increasing doses with no meaningful symptom change from baseline. You tolerate this subgroup at the tested doses.
• Fail. Clear symptom flare on one of the challenge days. Note the dose where it happened. Many people tolerate a lower dose than the one they failed at, which is worth retesting later.
• Unclear. Mild symptoms, or symptoms tangled up with stress, sleep, or another variable. Park it for the buffer week and retest cleanly.

A failed challenge is not the end of that food forever. The failed FODMAP challenge, what next post covers how to retest at a smaller dose and build a tolerance range rather than a binary yes/no.

The details on what to write down for each of these calls (symptom types, severity scale, Bristol stool scale, confounders) are in how to track the FODMAP reintroduction phase. Paper works. A vetted food database tied to symptom logs works better.

FODMAP stacking during reintroduction

One wrinkle that catches people off guard: passing a 3-day challenge at a standard serve does not mean unlimited amounts across every meal. FODMAPs from different foods add up. A low-FODMAP serve of avocado plus almonds plus sweet potato can still push you over threshold, even though none of those foods is "high FODMAP" individually.

During reintroduction, keep the rest of the day strictly low-FODMAP so the challenge dose is the only meaningful variable. Once you move into personalisation, FODMAP stacking becomes the main thing to watch.

After week 8

At the end of the schedule, you have a personal map: which FODMAP subgroups trigger symptoms, at roughly what dose, and which ones don't. That map is the point of the whole diet.

From there you move into what Whelan and colleagues call personalisation: eating the subgroups you tolerate freely and limiting the ones you don't to whatever dose works for you. For most people, the end state is much less restrictive than elimination but more deliberate than pre-diet eating. Refer back to what are FODMAPs for the categories and test foods if you want to retest any of them later; tolerance can shift over months and years, so a repeat challenge every 6 to 12 months on anything that failed is reasonable.

Where a tracker earns its keep

An 8-week schedule produces a lot of data: test food, dose, time eaten, symptoms by type, severity, Bristol score, confounders like sleep and stress. If any of that goes unrecorded, the week becomes harder to interpret, and memory past a few days is unreliable for exactly the signals you need.

That's what FODMAP Tracker is built for: log the test food against a vetted FODMAP database, timestamp symptoms in real time, and see foods and symptoms graphed against each other. The difference between "I think week 3 was bad" and "here's the exact dose and timing where mannitol flared" is the difference between guessing and knowing.

The app is in development. You can join the waitlist to get early access when it launches.

For the logging side of the protocol in depth, head to how to track the FODMAP reintroduction phase. For what to do with a failed challenge, failed FODMAP challenge, what next.

Track your symptoms and discover patterns with FODMAP Tracker. Includes a database of 1,000+ foods with FODMAP ratings.