Low FODMAP Reintroduction

Now it’s time to start putting foods back in.

The Low FODMAP diet isn’t designed to be followed strictly forever. Reintroduction helps us find out what your gut actually tolerates, so we can start making your diet more varied and less restrictive again.

We’re not looking for perfection and we’re not trying to test every high FODMAP food in existence. We simply want to learn enough about your individual tolerance to start broadening your diet with confidence.

Keep it simple

How reintroduction works

Start when your digestive symptoms are reasonably settled. They don’t have to be completely absent.

1 CHOOSE
Choose one challenge food.

2 TEST
Test it for up to 3 days.

3 RESET
Give your gut time to settle before the next challenge.

One challenge at a time

Keep the rest of your diet fairly familiar while you’re testing a food. That way, if your symptoms change, it’s much easier to understand why.

You don’t need to eat anything you’re allergic to, dislike, don’t normally eat, or choose not to eat. Where there are different options below, simply choose ONE that is relevant to you.

The 3-day challenge

Use the same food on each challenge day. If you’re tolerating it well, gradually increase the amount.

DAY 1 Start with a moderate amount.

DAY 2 Feeling okay? Increase it.

DAY 3 Still okay? Increase again towards an amount you’d normally eat.

If you develop a clear or significant return of your usual digestive symptoms, stop the challenge. You don’t need to force yourself through all three days.

Record what happened, return to the familiar Low FODMAP foods you know work for you, and wait until your symptoms have settled before moving on.

A reaction isn’t a failure. Finding that you tolerate a small amount but not a larger amount is useful information too.

If you already use the Monash FODMAP app, you can use its Reintroduction section for current food-specific challenge quantities. You don’t need to buy the app to use this guide.

What do I eat for the rest of the day?

Stick mainly to the Low FODMAP meals and foods that have already been working well for you while you’re doing each challenge.

Your challenge food is the deliberate change.

Keep your everyday meals easy

You can use my Low FODMAP recipe guide for familiar breakfasts, lunches, dinners and snacks while you’re working through reintroduction.

VIEW THE LOW FODMAP RECIPES

Your simple plan

5 weeks of reintroduction

This doesn’t need to become another huge restrictive project. We’ll work through five simple stages and learn what is actually relevant to you.

Week 1

Excess Fructose

We’re testing how well you tolerate excess fructose, which is found in certain fruits and sweeteners.

Choose ONE:

Mango
Honey

Use the same choice for your 3-day challenge.

Leave apple and pear until later. They contain a combination of fructose and sorbitol, which makes the result harder to interpret at this stage.

Week 2

Lactose

We’re testing how well you tolerate lactose, the sugar found in milk and some dairy foods.

Choose ONE:

Cow’s milk
Plain dairy yoghurt
Plain soft cheese that contains lactose
Plain dairy custard

Choose something you would genuinely want to include in your normal diet.

If you don’t consume dairy, you can skip this week. There is no reason to introduce dairy simply to complete a challenge.

Week 3

GOS

GOS are found mainly in beans, legumes and pulses.

Choose ONE:

Red kidney beans
Split peas
Baked beans
Falafel

Choose whichever is most relevant to the way you normally eat and use the same food throughout your challenge.

Some foods can contain more than one type of FODMAP, so make sure you record the actual food you tested, not simply “GOS”.

Week 4

Polyols

There are two main polyols we want to learn about: sorbitol and mannitol.

Rather than turning these into two whole extra weeks, we’ll keep them together in one polyol stage.

Sorbitol

Choose ONE:

Apricot
Peach
Plum

Complete your 3-day challenge with one of these fruits.

Mannitol

Choose ONE:

Mushrooms
Celery

If understanding both polyols is relevant to you, allow your gut to settle after the first challenge before testing the second.

You don’t need to cram both challenges into seven days. The aim is useful information, not sticking rigidly to a calendar.

Week 5

Fructans

Fructans are found in foods including wheat, onion, garlic and some vegetables.

For your main fructan challenge, choose the food that is most useful to understand in your normal diet.

Choose ONE:

Wheat pasta
Wholemeal wheat bread
Onion
Garlic
Leek

Use your chosen food for the 3-day challenge in exactly the same way as the previous weeks.

Important: fructans are slightly different from the other FODMAP groups because some people tolerate one source better than another. For example, you might tolerate wheat but struggle with garlic.

That does not mean everybody needs separate weeks of wheat, onion, garlic and leek challenges. Start with the one most relevant to you. We can investigate another source later only if there is a useful reason to do so.

Only if useful later

You don’t have to test everything

By the end of these challenges, we should have a much better idea of what you tolerate.

There may be a few foods that are still worth investigating, but only if knowing the answer would actually help you.

Examples

Apple or pear: useful later if you want to see how you tolerate the combination of fructose + sorbitol.

Another fructan source: useful if, for example, you tolerated wheat but particularly want to know whether onion or garlic causes symptoms.

A food you really miss: if there’s a particular food you want back in your diet, that can be more useful to test than working mechanically through a long list.

The point is not to keep testing indefinitely. Once we’ve gathered enough useful information, we move on to personalisation and start broadening your diet.

How long do I leave between challenges?

Allow around 2–3 days between challenges, or until any symptoms have settled.

CHALLENGE → RESET → NEXT CHALLENGE

If you sailed through a challenge without significant symptoms, great. Record the result and move on after your reset period.

If you reacted, wait until your gut is back to its usual baseline before testing something else.

Remember: sometimes it isn’t the food

Gut symptoms can be affected by plenty of other things too. Make a note in your tracker if anything unusual happens during a challenge, such as:

Illness or a stomach bug
Your period
Unusual stress
Poor sleep
Eating out
Alcohol
More caffeine than usual
A significant change in routine
Another unusual food or drink

That doesn’t automatically mean the challenge is ruined. It simply gives us useful context when we look at your results.

The goal is a more varied diet, not a perfect Low FODMAP diet

You may discover that some FODMAPs don’t bother you at all. You may tolerate others perfectly well in smaller amounts but notice symptoms with larger portions.

There may also be a few foods that genuinely don’t suit you.

That’s exactly what we’re trying to find out.

Once we know enough, we start putting the foods you tolerate back into your everyday diet.

Your Reintroduction Tracker

Keep a simple record as you go

Use your tracker during each challenge so we can see what you tested, how much you ate and how your gut responded.

Your challenge food and amount
What you ate and drank
Any digestive symptoms
Symptom severity from 0–10
Anything else worth noting, such as bowel changes, your period, illness, stress, sleep, alcohol or eating out

It’s a fillable PDF, so you can type straight into it on your phone, tablet or computer, or print it and complete it by hand.

OPEN YOUR 7-DAY TRACKER

If you’re completing it digitally, remember to save the PDF as you go.

Evidence & further reading

Want to know more?

This guide is based on Monash University’s approach to Low FODMAP reintroduction, adapted into a simpler practical format for use with your nutrition programme.

Practical tips for FODMAP reintroduction
2025 FODMAP Reintroduction Update
Order of FODMAP reintroduction
Fructans and FODMAP reintroduction
Interpreting reintroduction challenges