Once you’ve completed the elimination phase of the FODMAP diet, take these steps to start adding foods back in one-by-one.

After working with your dietitian to limit or eliminate high FODMAP foods from your diet for about 2-6 weeks, it’s time to start reintroducing those foods back into your diet.

It may sound counterintuitive to add these “trigger” foods back in, but a low FODMAP diet is not a long-term eating plan—it’s a restrictive diet that’s designed to help you pinpoint your specific food triggers so you can craft a custom-diet that can help you manage your symptoms.

At first, your dietitian will ask you to introduce types of FODMAPs one at a time, so you can figure out which are problematic, and which are well-tolerated. These are called food challenges. 

However, it’s important to start reintroducing foods in the right way.

Before You Get Started

The reintroduction phase is very methodical, and it can take about six to eight weeks to complete. During that time, it’s important to remember these basic rules:

  1. Only reintroduce one FODMAP group at a time.
  2. Choose a test food that only contains one type of FODMAP.
  3. Use the same test food for each of the three challenge days.
  4. Incorporate the test food three times throughout the test week—up to once per day. 
  5. Be mindful of portion sizes—avoid consuming the food in excessive quantities. You might be advised to scale up the serving size each day to test different “dosages” of that FODMAP.
  6. Keep a log of the test food you eat and any symptoms experienced for each challenge.
  7. Continue to restrict all other FODMAPs that aren’t being challenged until tolerance or intolerance is confirmed.
  8. If intolerance is confirmed, re-test in 2-3 months, as tolerance to FODMAPs may change over time.

What Foods to Include in a Reintroduction Challenge

Your dietitian will work with you to come up with the reintroduction plan and food challenges that make the most sense for you. Examples for each FODMAP challenge include:

Lactose

A food challenge for lactose, which primarily is found in dairy products, may consist of: 

  • 1/2 cup milk
  • 3/4 cup plain yogurt (one without other FODMAP ingredients, like high fructose corn syrup)

Fructose

These foods are known for being on the sweeter side, though certain vegetables contain excess fructose. Some examples of a food challenge for fructose include:

  • 1/2 mango
  • 2 teaspoons of honey
  • 1 fresh fig
  • 2-3 spears of asparagus
  • 1/4 cup sugar snap peas

Polyols

Your registered dietitian will recommend testing foods containing sorbitol separately from those containing mannitol. These challenges may include:

  • Sorbitol
    • 5 blackberries 
    • 1 yellow peach
  • Mannitol
    • 1/2 cup mushrooms
    • 1/3 cup cauliflower
    • 1 large celery stalk
    • 1 cup sweet potato

Fructans

Fructans are a complex group of foods. Therefore, your dietitian may recommend multiple food challenges for fructans, such as:

  • 2 slices of whole wheat bread
  • 1 cup cooked pasta
  • 1 tablespoon chopped onion
  • 1 clove of garlic

GOS

Compared to fructans, GOS are predominately found in legumes. As a result, your food challenge may consist of:

1/2 cup kidney beans, lima beans, or soybeans

Remember: It’s important to follow the challenge plan in the exact order your dietitian recommends. Be sure to take a few days off in between reintroduction of each new food in order to avoid any potential crossover effects.

Mapping Out a Reintroduction Plan

Once you have the green light from your registered dietitian, here’s what your food challenge may look like:

  • Day 1: Eat the first challenge food. Remember to otherwise stick with your low FODMAP diet. If you don’t experience symptoms, move on to day 2. 
  • Day 2: Double the portion of the challenge food or eat the portion twice during the day. If you don’t experience symptoms, move on to day 3. 
  • Day 3: Eat the same portion as day two; or, triple the portion compared to the day 1 portion size.

Remember: If you start to experiencing moderate to severe symptoms while reintroducing any new food, stop eating it, and talk to your dietitian. They may recommend going back to the low FODMAP diet until symptoms resolve and you’re symptom-free for three days. 

When it’s time to re-test that food, your dietitian may recommend starting with half of the portion size you previously tested with. 

Work With Your Dietitian

The reintroduction phase is complicated. In order to make sure you’re following the proper steps, continue to work with your dietitian, who can help map out the right reintroduction plan for you. Your dietitian can also help you interpret your response to each food, and determine the best course of action.