Guide · Food and modes · 3 min read

The three steps of FODMAP

By the CalJab team, with sources · Last reviewed October 21, 2026

FODMAPs are a group of sugars shown to irritate the gut and cause IBS symptoms such as bloating, gas, constipation, diarrhea and pain. ¹ The Monash University Low FODMAP Diet has three steps, and the aim is a personal diet that is as little restrictive as possible for the long term. ¹

1. Elimination (2 to 6 weeks)

• You swap high FODMAP foods for low FODMAP alternatives; the aim is to get symptoms under control. ¹
• It is a swap diet, not a cut-out diet: for example, your daily apple for an orange, or onion for chives. ²
• This step is best started under the supervision of a dietitian. ²

2. Reintroduction (8 to 12 weeks)

• If your symptoms improved in step 1, it is time to bring FODMAPs back; you stay on a low FODMAP diet meanwhile. ¹
• Each FODMAP group is tested on its own: fructose, lactose, sorbitol, mannitol, fructans and GOS. You eat 1 test food once a day for 3 days. ¹
• Leave a break of a few days between tests; a dietitian helps you read your responses. ²

3. Personalization (long term)

• FODMAPs you tolerate well go back into your diet; only those that trigger symptoms stay limited, and only enough to keep symptoms in check. ¹
• FODMAP tolerance can change over time; try foods that did not suit you again in a few months. ²

Before you start

The NHS advice is for people who have been diagnosed with IBS. ³ If you need to avoid lots of different foods to control your symptoms, see your doctor; they may refer you to a dietitian. ³ Not skipping meals and not eating too quickly are advised too. ³

In CalJab

On the FODMAP card in Guide you choose which step you are in; the app does not guess. Plans and recipes use the low FODMAP filter. During reintroduction, what you log in How are you makes it easier to look back alongside what you ate.

Follow the low FODMAP diet together with a dietitian.

Written by the CalJab team, with sources. It does not replace your doctor's advice. Found a mistake? Write to support@caljab.app.