Eating style
Low-FODMAP
A short-term, dietitian-led elimination diet for people with diagnosed IBS. How the three steps work and why it is not meant to be permanent.
What FODMAPs are
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols: short-chain carbohydrates that are poorly absorbed in the small intestine. They draw water into the gut and are fermented by bacteria, producing gas. That happens in everyone. In people with irritable bowel syndrome (IBS), whose gut is more sensitive, it can bring on pain, bloating and altered bowel habit.
They occur in many otherwise nutritious foods, including wheat and rye, onions, garlic, most legumes, cow’s milk and yoghurt, apples, pears and mango. FODMAP content cannot be guessed from a food’s other nutrition values. It has to be measured in a laboratory, which is the work behind Monash University’s food lists.
The three steps
Step 1 swaps high-FODMAP foods for low-FODMAP alternatives for two to six weeks. If symptoms do not improve in that time, FODMAPs may not be your trigger. Step 2 keeps the low-FODMAP base and tests one FODMAP group at a time, each over three days, to find out which ones you tolerate.
Step 3 is the long-term diet: everything you tolerated goes back in, and only your personal triggers stay limited. Monash describes the result as less restrictive and more nutritionally balanced than step 1. The strict phase is a test with an end date, not a way of eating for life.
What the evidence shows
A 2022 network meta-analysis of 13 randomised trials with 944 patients ranked the low-FODMAP diet first for overall IBS symptoms, ahead of habitual diet and the other approaches tested. The authors noted that most trials were run in specialist care and did not study the reintroduction steps. Monash’s own research reports improvement in about three in four people with IBS.
NICE recommends it only when symptoms persist after general lifestyle and dietary advice, and says such advice should be given only by a healthcare professional with expertise in dietary management. The diet is a way to manage symptoms. It does not cure IBS, and it is not designed for people who do not have it.
Recipes on this site
We do not label recipes low-FODMAP and there is no recipe shelf on this page. FODMAP content depends on the specific food and the size of the serving, and none of that can be worked out from macros. During the strict phase, use the lists your dietitian gives you or the Monash app, and check every ingredient of a recipe against them.
Worth knowing
- Get a diagnosis first. Symptoms that look like IBS can have other causes, so see your GP before changing your diet.
- Do this with a dietitian. The strict phase removes many foods and is easy to get wrong or to stay on for too long.
- If you have, or have had, an eating disorder, an elimination diet is not appropriate without specialist supervision.
Common questions
Can I stay on the strict phase if it works?
It is not designed for that. Monash sets the strict phase at two to six weeks, followed by reintroduction, so that you end up limiting only the foods that trigger your symptoms.
Is low-FODMAP the same as gluten-free?
No. Wheat and rye are limited because of their fructans, a type of FODMAP, not their gluten. A gluten-free food can still be high in FODMAPs, and people with coeliac disease need strict gluten avoidance regardless.
Sources
General information, not medical or dietary advice. Speak to a doctor or registered dietitian about your own situation.