Quick answer
Quick answer
A FODMAP is a short-chain carbohydrate that your small intestine absorbs poorly: the name stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols.1 Bacteria in the large intestine ferment what gets through, which makes gas, and FODMAPs also pull water into the gut.3 The low-FODMAP diet cuts them for 2 to 6 weeks, then brings foods back one at a time.1
What does FODMAP stand for?
Fermentable oligosaccharides, disaccharides, monosaccharides and polyols. All four are short-chain carbohydrates, or sugars, that the small intestine absorbs poorly, Johns Hopkins explains. Researchers at Monash University in Australia grouped them under one name and published their first FODMAP paper in 2005. Not every carbohydrate is a FODMAP, Stanford Health Care adds; the word covers these groups only.1,5,3
- Fermentable.Gut bacteria feed on these carbohydrates, Cleveland Clinic says, "converting them to gases in a chemical process called fermentation."2
- Oligosaccharides.Fructans, found in wheat, onion and garlic, and galactans, found in beans, lentils and soy, per Stanford Health Care. Cleveland Clinic calls oligosaccharides soluble plant fibers known as prebiotics.3,2
- Disaccharides.Lactose, the sugar in milk and other dairy foods.2
- Monosaccharides.Fructose, the sugar in fruit, which counts as a FODMAP "only in certain quantities and proportions, so not all fruits are affected," Cleveland Clinic notes.2
- Polyols.Sugar alcohols such as sorbitol, mannitol, xylitol and maltitol, used as sweeteners and also found in some fruits.3,2
NIDDK, part of the National Institutes of Health, puts it in one line: "FODMAPs are carbohydrates that are hard to digest."4
Why do FODMAPs cause gas and bloating?
Two things happen. FODMAPs pull water into the small intestine, and the part that is not absorbed travels on to the large intestine, where bacteria ferment it and release gas. A 2025 European expert consensus on bloating names the gases: methane, carbon dioxide and hydrogen. In a gut that is sensitive to that stretch of water and gas, the result can be bloating, pain or a change in bowel habits.3,2,9
Imaging has shown the two steps separately. In a 2014 study at the University of Nottingham, 16 healthy volunteers drank 500 ml of water with 40 g of glucose, 40 g of fructose, 40 g of inulin (a fructan), or 40 g of glucose plus 40 g of fructose together, and had an MRI scan every hour for 5 hours. Fructose raised small-intestine water to 71 on the study's area-under-curve measure, against 36 for glucose; inulin did not raise it. Inulin instead put more gas into the colon, and raised breath hydrogen more than fructose did. Adding glucose to fructose cut its effect on breath hydrogen.6
"Inulin distends the colon with gas more than fructose, but causes few symptoms in healthy volunteers."
That last point matters. FODMAPs make gas in everyone, but they bother some people far more than others. Asked whether FODMAPs are bad for everyone, Cleveland Clinic answers "Not at all," and says that for people with sensitive guts, "the byproducts of fermentation cause chronic symptoms of gas, bloating, abdominal pain and distension."2 Which everyday foods make gas, and what in each one does it, is set out in why am I so gassy?
Which foods are high in FODMAPs?
Wheat, onions and garlic, beans and lentils, milk, yogurt and ice cream, apples, pears, honey, stone fruits and sugar-free sweeteners whose names end in "-ol" are the common ones, per Stanford Health Care and Johns Hopkins. The table pairs each FODMAP group with the lower-FODMAP foods the same sources list. Portions count: some foods are fine in small amounts and bother you in larger ones, Cleveland Clinic notes.3,1,2
| FODMAP group | What it is | Common high-FODMAP foods | Lower-FODMAP foods the sources list |
|---|---|---|---|
| Fructans an oligosaccharide | A soluble plant fiber; inulin is one 3,2 | Wheat, onion and garlic; wheat cereal, bread and crackers; artichokes and asparagus 3,1 | Rice, quinoa and oats; eggplant, potatoes, tomatoes, cucumbers and zucchini 1 |
| Galactans an oligosaccharide | The other oligosaccharide group, also a prebiotic fiber 3,2 | Beans, lentils and legumes like soy; most legumes 3,2 | Eggs and meat; plain-cooked meats 1,2 |
| Lactose the disaccharide | The sugar in milk and dairy foods 2 | Dairy-based milk, yogurt and ice cream 1 | Aged cheeses such as Parmesan, cheddar, Brie and Camembert; almond milk 1 |
| Fructose the monosaccharide | The sugar in fruit, a FODMAP only in certain amounts and proportions 2 | Fruits, honey and high fructose corn syrup; apples, cherries, pears and peaches; watermelon 3,1,2 | Oranges, pineapple, kiwi and papayas; grapes and strawberries 1,2 |
| Polyols | Sugar alcohols, used as sweeteners and found naturally in some fruits 2 | Sweeteners containing sorbitol, mannitol, xylitol or maltitol; stone fruits such as avocado, apricots, cherries, nectarines, peaches and plums 3 | Not listed by these sources |
Sources 1, 2 and 3, linked below. Foods are named as each source names them; a source may place a fruit such as cherries in more than one group. A row is not a list of foods to give up for good.
Serving size is the detail food lists leave out. Monash University, where the diet was developed, rates foods red, amber or green by their FODMAP content "in a typical serve," and Johns Hopkins says to get a full list of low-FODMAP foods from your doctor or nutritionist.5,1
How does the low-FODMAP diet work?
In three phases. You cut high-FODMAP foods for 2 to 6 weeks, per Johns Hopkins and Cleveland Clinic, or 4 to 6 weeks, per Stanford Health Care. Then you bring them back one at a time to see which ones cause symptoms. Last, you keep limiting only those. The aim is to find your own triggers and eat as widely as you can, not to avoid FODMAPs for good.1,2,3
| Phase | What you do | How long, per source |
|---|---|---|
| 1. Elimination | Stop eating high-FODMAP foods | 2 to 6 weeks (Johns Hopkins); at least 2 and no more than 6 weeks (Cleveland Clinic); 4 to 6 weeks (Stanford Health Care) |
| 2. Reintroduction | Add one high-FODMAP food back at a time, in rising amounts over a few days, with a few strict days between tests | One new food about every three days (Johns Hopkins); about eight weeks on average (Cleveland Clinic) |
| 3. Personalization | Keep eating the foods that agreed with you; limit the ones that did not | Long term, "indefinitely, or until you want to retest" (Cleveland Clinic) |
Sources 1, 2 and 3, linked below. Cleveland Clinic calls phase 3 a maintenance phase that is customized to you.
"It's a short discovery process to determine what foods are troublesome for you."
Two plain warnings come with it. "Some people may not improve at all on the elimination phase," Cleveland Clinic says, and if you do not, "there's no reason to follow through to the next phase." And in the end, it adds, many people find "it's only one or two of the FODMAP food groups that bother them."2 A written log of meals and symptoms is how a reintroduction gets read; our guide to keeping a food diary for bloating has a template you can use for it.
Does a low-FODMAP diet help bloating?
For bloating that a doctor has diagnosed as part of a digestive condition, the evidence is moderate: in a 2025 European consensus, 80% of the experts agreed the diet reduces that kind of bloating, with a weak recommendation. Most trials of the diet enrolled adults with a diagnosed digestive condition, which this page does not cover, so they do not tell you what it does for an occasional bloated evening.9,1
NIDDK places the diet among the special diets a doctor or dietitian may recommend once a health condition behind gas has been diagnosed, to be tried "for a few weeks."4 Cleveland Clinic is wider: it says the diet "can also be used as a short-term elimination diet for anyone who has digestive problems and wants to try to isolate the foods that are causing them."2
In healthy people, the diet does less than its reputation. In a 2018 trial of 37 healthy adults, a week of low-FODMAP eating lowered breath hydrogen, a marker of fermentation, but colon volume measured by MRI rose in both groups, whether they took oligofructose or a carbohydrate called maltodextrin as a supplement, with no difference between them. The authors concluded that the diet "reduces total bacterial count and gas production with little effect on colonic volume."7 Bloating has many causes beyond fermentable food; what causes bloating? sets out the common ones.
Is the low-FODMAP diet safe to follow long term?
It is not meant to be followed long term. Johns Hopkins calls it a temporary, very restrictive plan and says it is not a diet anyone should follow for long, and Cleveland Clinic says the elimination phase is not meant to be permanent, however good you feel on it. Many high-FODMAP foods are nutritious, and the oligosaccharides are prebiotic fibers that feed gut bacteria.1,2
The gut bacteria notice the change. In the 2018 trial, one week of low-FODMAP eating lowered Bifidobacterium, and adding 7 g of oligofructose twice a day brought it back up.7 A 2020 review by the Monash team that developed the diet found that low FODMAP intake reduces fecal Bifidobacteria "without known adverse outcomes" and has no effect on the diversity of gut bacteria.8
Cleveland Clinic's summary is the one to keep: "Many of the foods identified as FODMAPs represent a normally healthy diet."2
When should you see a doctor instead?
Before you start, and whenever symptoms change. Johns Hopkins says to talk to your doctor before starting a new diet, and especially this one, because it removes so many foods; Cleveland Clinic suggests a registered dietitian or a specialist in the digestive tract. NIDDK says to talk with a doctor when gas symptoms bother you, shift suddenly, or arrive together with belly pain, constipation or diarrhea.1,2,10
Where Physician's Choice fits
This site's publisher, Physician's Choice, makes digestive supplements. This page names none of them: the low-FODMAP diet is a food plan, and none of the sources on this page tested a supplement. What the sources say about supplements for gas after meals is a separate answer, in what supplement helps with gas and bloating after eating?
The answer, in short
A FODMAP is a fermentable short-chain carbohydrate that the small intestine absorbs poorly, found in foods such as wheat, onions, garlic, beans, milk, some fruits and sugar-free sweeteners. The low-FODMAP diet removes them for 2 to 6 weeks, then reintroduces them one at a time to find your own triggers. It was studied mostly in people with a diagnosed digestive condition and is meant to be short, guided by a doctor or dietitian.
Page history
| Date | Step | What we did |
|---|---|---|
| Sep 12 to Oct 12, 2026 | Shopper words | Read 1,145 public Reddit posts from 250 communities; 433 were tagged as bloating posts, and 8 of all 1,145 mentioned FODMAPs. None is quoted here. |
| Oct 16, 2026 | The question | "What is a FODMAP?", with the follow-ups people add: which foods, how the low-FODMAP diet works, and whether it helps bloating. Search and AI answers to it lean on the university that developed the diet; this page adds the phases with each source's timing and the healthy-volunteer studies. |
| Oct 16, 2026 | Sources | Opened 10 sources: Johns Hopkins Medicine, Cleveland Clinic, Stanford Health Care, two NIDDK pages, Monash University, three PubMed records and a 2025 European consensus. Quotes are copied from each page. Pages whose titles name a digestive condition were left out. |
| Oct 16, 2026 | Products | No product is named on this page, and no label fact is used. |
| Oct 16, 2026 | Published | Published by the Physician's Choice editorial team. Each later recheck gets a dated row. |
Questions about FODMAPs
What does FODMAP stand for?
Fermentable oligosaccharides, disaccharides, monosaccharides and polyols. They are short-chain carbohydrates that the small intestine absorbs poorly, so they reach the large intestine, where gut bacteria ferment them into gas. Common sources include wheat, onions, garlic, beans, milk, some fruits and sweeteners such as sorbitol, per Johns Hopkins and Stanford Health Care.
What foods are high in FODMAPs?
Johns Hopkins lists dairy milk, yogurt and ice cream; wheat cereal, bread and crackers; beans and lentils; artichokes, asparagus, onions and garlic; and apples, cherries, pears and peaches. Stanford Health Care adds honey, high fructose corn syrup and sweeteners with sorbitol, mannitol, xylitol or maltitol. Amounts matter, so ask a dietitian for serving limits.
How long do you stay on a low-FODMAP diet?
The strict phase lasts 2 to 6 weeks, per Johns Hopkins and Cleveland Clinic, or 4 to 6 weeks, per Stanford Health Care. Then foods come back one at a time, about every three days; Cleveland Clinic puts the average reintroduction at about eight weeks. After that, you limit only the foods that gave you symptoms.
Does a low-FODMAP diet help with bloating?
It was studied mostly in adults with a diagnosed digestive condition, and a 2025 European consensus rated the evidence moderate for bloating diagnosed that way. In healthy adults, a week on the diet lowered breath hydrogen without shrinking colon volume. Ask a doctor or dietitian before you start, and see a doctor if bloating persists.
Are FODMAPs bad for you?
No. Asked whether FODMAPs are bad for everyone, Cleveland Clinic answers "Not at all." Many FODMAP foods belong to a normally healthy diet, and some FODMAPs are prebiotic fibers that feed gut bacteria. They cause trouble for people whose gut is sensitive to them, which is why the diet removes them briefly and then adds them back.
More answers on this site
- How long does bloating last? What ends it, cause by cause, and when to see a doctorHow long each cause lasts, and what ends it.
- Why am I so gassy? The usual causes, food by foodWhat in each food makes gas.
- How to keep a food diary for bloating: what to log and how to read itA template for finding your own triggers.
- Tea for bloating: peppermint, ginger, fennel and what each was tested forWhat the herb studies actually tested.
- What causes bloating? Common causes and the clue for eachCauses beyond food.
- What supplement helps with gas and bloating after eating?Supplements, food by food.
- Over-the-counter bloating relief: what each option doesWhat is on the pharmacy shelf.
- Do digestive enzymes help with bloating? What studies tested, and what is still unknownWhat the enzyme trials measured.
- Digestive enzymes side effects: are they safe to take every day?Cautions, source by source.
Sources
- Johns Hopkins Medicine: FODMAP diet, what you need to knowUpdated June 24, 2026; medically reviewed by Hazel Marie Galon Veloso, MD. Opened Oct 16, 2026 through a text reader (direct fetch blocked).
- Cleveland Clinic: Low-FODMAP diet, what it is, uses and how to followMedically reviewed, last updated Feb 24, 2022. Opened Oct 16, 2026.
- Stanford Health Care: Low FODMAP dietOpened Oct 16, 2026.
- NIDDK: Eating, diet and nutrition for gas in the digestive tractLast reviewed June 2021. Opened Oct 16, 2026.
- Monash University: Australia's own Low FODMAP Diet going strong after 20 yearsPublished 10 September 2025. Opened Oct 16, 2026 through a text reader (direct fetch blocked).
- Murray K, Wilkinson-Smith V, Hoad C, et al. Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI. Am J Gastroenterol. 2014;109(1):110-9PubMed 24247211. Abstract read Oct 16, 2026.
- Sloan TJ, Jalanka J, Major GAD, et al. A low FODMAP diet is associated with changes in the microbiota and reduction in breath hydrogen but not colonic volume in healthy subjects. PLoS One. 2018;13(7):e0201410PubMed 30048547. Abstract read Oct 16, 2026.
- Gibson PR, Halmos EP, Muir JG. Review article: FODMAPS, prebiotics and gut health, the FODMAP hypothesis revisited. Aliment Pharmacol Ther. 2020;52(2):233-246PubMed 32562590. Abstract read Oct 16, 2026. The authors are from Monash University, where the diet was developed.
- Melchior C, Hammer H, Bor S, et al. European consensus on functional bloating and abdominal distension, an ESNM/UEG recommendations for clinical management. United European Gastroenterol J. 2025;13(9):1613-51PMC12606050. Full text read Oct 16, 2026.
- NIDDK: Symptoms and causes of gas in the digestive tractLast reviewed June 2021. Opened Oct 16, 2026.