Article

The Challenge Phase of the Low FODMAP Diet

Published on Tuesday, April 05, 2022
by Haley McGaha

Health & Wellness

The Low FODMAP Challenge Phase: Identifying Your IBS Triggers

The purpose of the challenge phase is to identify the FODMAP groups that may be triggering your symptoms if you are living with Irritable Bowel Syndrome.

The Low FODMAP diet has been shown to be an effective strategy for symptom relief in many people with IBS. The first phase of the diet is the elimination phase, followed by the challenge (or reintroduction) phase, and finally, the personalization phase—your “new normal” way of eating.

Why Is the Challenge Phase Important?

The goal of the challenge phase is to identify specific dietary triggers while reintroducing well-tolerated foods.

This step is critical because it helps:

Reduce unnecessary dietary restriction
Expand food variety
Support better long-term gut health

Over-restricting FODMAPs in the long term may negatively affect the gut microbiota, so reintroducing tolerated foods is important for maintaining a balanced and sustainable diet.

When Should You Start the Challenge Phase?

Most people begin to notice symptom improvement within 3–4 weeks of the elimination phase.

The challenge phase typically begins after 2–6 weeks, depending on symptom control. This timeline can be adjusted based on your individual response.

How to Approach the Challenge Phase

During the challenge phase, structure and consistency are key.

Introduce one FODMAP group at a time
Monitor and record symptoms carefully
Track both the type and severity of symptoms

If a specific food group causes a noticeable increase in symptoms, it’s recommended to stop that challenge and return to the elimination phase before moving on.

If symptoms remain controlled, you can gradually increase the portion size. A common approach is:

Day 1: Small portion
Day 2: Moderate portion
Day 3: Full portion

This helps assess your tolerance at different intake levels.

Understanding FODMAP Groups

Each FODMAP category contains different types of fermentable carbohydrates that may trigger symptoms.

Here are the main groups and common food examples:

Lactose: yogurt, milk, buttermilk, cottage cheese, kefir
Fructose: honey, agave, apples, dried fruit, high fructose corn syrup
Fructans: onions, garlic, wheat products, rye, barley
Galactans (GOS): chickpeas, lentils, beans
Polyols: sugar-free gum/candy, blackberries, mushrooms, avocado

(For more detailed and portion-specific guidance, the Monash University FODMAP Diet App is a helpful resource.)

The Importance of the “Washout” Period

Between each challenge, it is recommended to return to the elimination phase for 2–3 days.

This “washout” period allows symptoms to settle, making it easier to clearly identify which foods may be triggering a response.

What Happens After the Challenge Phase?

Once you’ve tested each FODMAP group, you can begin to build your personalized diet:

No symptoms: Foods can be fully reintroduced
Mild symptoms: Foods may be tolerated in smaller portions or less frequently
Severe symptoms: Foods are best limited or avoided (for now)

It’s important to remember that tolerance can change over time. Factors like stress, sleep, and overall gut health can influence how your body responds to certain foods.

Re-challenging previously problematic foods at a later time is often encouraged.

The Bottom Line

The challenge phase is where the Low FODMAP diet becomes truly personalized.

Instead of following a highly restrictive plan long-term, this phase helps you:

Identify your unique triggers
Reintroduce as many foods as possible
Support both symptom control and gut health

_{Monash University. (n.d.).}_{The Monash University Low FODMAP diet app}_{. Monash FODMAP.}_{https://www.monashfodmap.com}
_{Staudacher, H. M., & Whelan, K. (2017). The low FODMAP diet: Recent advances in understanding its mechanisms and efficacy in IBS.}_{Gut, 66}_{(8), 1517–1527.}_{https://doi.org/10.1136/gutjnl-2017-313750}
_{Tuck, C., & Barrett, J. (2017). Re-challenging FODMAPs: The low FODMAP diet phase two.}_{Journal of Gastroenterology and Hepatology, 32}_{(Suppl 1), 11–15.}_{https://doi.org/10.1111/jgh.13687}