By: Parco Man, BSc, M.Diet, dietetic student-volunteer, reviewed by Amélie Charron, RD and the JM Nutrition Team
In this post our team of dietitians for digestive health examines IBS, FODMAPs and what can actually help.
IBS and FODMAP: Introduction
If you’ve ever experienced bloating after every meal, spent more time planning your day around bathroom access than the actual plans themselves, or googled “why does my stomach hurt all the time”, you’re not alone. And, you’re certainly not imagining it.
Irritable Bowel Syndrome (IBS) affects a large number of people, yet so many walk away from a diagnosis with more questions than answers.
If this sounds familiar and may be you, continue to read on.
Let’s break down what IBS actually is, why the Low-FODMAP diet keeps coming up, and what it can or cannot do.
What is IBS?
IBS or Irritable Bowel Syndrome is a functional bowel disorder. This means the gut doesn’t show any visible damage or structural problems on a scope, scan, or blood test, but it still isn’t working the way it should. (Hungin, 2003)
People with IBS usually have oversensitive nerves around their intestines. Because of this, gut symptoms, such as increased gas and water, can manifest as painful episodes of bloating, abdominal pain, and altered bowel habits, such as constipation, diarrhea, or a mix of both. (Ahuja,2024)
However, what makes this even more striking is the scale of the problem.
Global estimates suggest that over 366 million people are living with undiagnosed IBS.
What’s more, among those who do have a formal diagnosis, millions still report significant dissatisfaction with the care they receive. (Oka P, 2020). These numbers are a reminder that if your gut symptoms have been brushed off or left unexplained, you’re far from alone.
How is IBS Diagnosed?
As nothing shows up on standard testing, such as blood tests and endoscopies, IBS is generally diagnosed based on your symptoms and history, evaluated by a practitioner.
The most widely used diagnostic tool is the Rome IV criteria.
In simple terms, it looks at whether you’ve had recurring, chronic abdominal pain alongside changes in bowel habits for at least one day in the last 3 months, with symptoms first appearing at least six months ago. (Oka P, 2020)
As the Rome IV diagnostic criteria are a pattern-recognition approach rather than a single medical test, ruling out other conditions is crucial.
Red Flags: Don’t Skip This Step
Here’s the part that’s easy to rush past: IBS symptoms overlap with a long list of other conditions.
These include: coeliac disease, inflammatory bowel disease (IBD), diverticular disease, certain cancers, pelvic floor disorders, endometriosis, and issues related to the pancreas, bile acids, endocrine system, or lactose intolerance.
Before confirming an IBS diagnosis, your healthcare professional should review for “red flags,” such as family history, age, and certain symptoms, to assess the risk of other, more serious complications.
A misdiagnosis can delay treatment for something more serious or send you down a management path that was never going to fix the actual problem.
If you’re dealing with ongoing symptoms that affect your daily life, please see a healthcare practitioner for a proper assessment before self-managing.
I’ve Been Diagnosed with IBS. Now What?
Here’s something many people don’t expect: Being diagnosed with IBS often comes with surprisingly little explanation about why it’s happening or what to do next. That gap is real, and it’s not your fault if you feel overwhelmed or confused.
The honest answer is that the exact cause of IBS isn’t fully understood yet. But research has identified one major dietary trigger for many people: a group of carbohydrates known as FODMAPs.
What Are FODMAPs?
FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. It seems complicated, but the concept is fairly simple.
When FODMAPs are ingested, they draw water into the small intestine, leading to intestinal expansion and changes in the movement of gut contents.
Since FODMAPs are not fully digested or absorbed in the small intestine, they then transit into the large intestine (El-Salhy, 2012).
Additionally, the bacteria in the large intestine (gut microbiota) use FODMAPs as an energy source. They rapidly break down FODMAPs, producing gas.
These actions lead to more expansion of the intestinal contents and intestinal wall. As people with IBS have a sensitive gut, this change and expansion of the gut leads to pain and discomfort. (El-Salhy, 2012)
In short, for someone with IBS, an ordinary meal can turn into hours of bloating and discomfort. It is not because their gut is doing anything fundamentally different, but because their gut is more sensitive to it. The same digestive process happens in everyone, but people without IBS usually experience far less pain and discomfort from it.
IBS and The Low FODMAP Diet
Undoubtedly, the low-FODMAP diet is one of the most well-researched dietary approaches for managing IBS.
That said, it’s not a single “diet” you stay on forever. Rather, it is a structured, three-phase process designed to land you on a long-term eating pattern that’s as unrestricted as possible while still keeping your symptoms under control.
Ideally, this is done with support from a registered dietitian, who can guide the process, troubleshoot along the way, and answer the questions that come up.
Phase 1: Elimination (Low-FODMAP Diet)
Phase 1 is about identification and relief.
High and moderate FODMAP foods are swapped for low-FODMAP alternatives, typically for two to six weeks.
Essentially, the goal is to find out whether reducing FODMAPs actually improves your symptoms.
If there is no significant symptom relief, the dietitian might review the elimination process again to determine why there is insufficient relief after reducing FODMAPs.
When you are preparing your own meals, you can do the shopping following the resources given by your dietitian.
Choose
Choose foods low in FODMAPs and avoid ingredients high in FODMAPs.
Avoid
Some common ingredients to avoid are onion, garlic and milk.
This low-FODMAP diet food guide is a resource developed by Gastroenterology Consultants of San Antonio and summarizes some common FODMAP food swaps. Please note that this list is for reference only, and a healthcare professional such as a dietitian can help determine whether the low FODMAP diet is appropriate for you.
Eating Out on a Low-FODMAP Diet
Eating out while you are on a low-FODMAP diet can be a challenge, as most restaurants do not provide specific low-FODMAP options.
That said, however, here are some tips provided by Monash University for eating out during a low-FODMAP diet.
1. Look at ingredients and menus online to plan for restaurants or cafes with suitable low-FODMAP options.
2. Choose protein-based meals (fish, red meats, or poultry) served with vegetables, salad, potato, rice, rice noodles on the side rather than bread or pasta.
3. Avoid heavily sauced, rich dishes (such as curries) as they are harder to modify and often contain garlic and onion.
4. Avoid dishes made with stock (such as soups and risottos) as they often contain garlic and onion.
5. Ask for a recommendation regarding dishes that do not contain onion or garlic.
- Ask for dips, sauces and dressings to be served separately (these often contain garlic and onion).
- Call the restaurant in advance (outside of busy hours) for more complicated requests.
Phase 2: FODMAP Reintroduction
If Phase 1 brought meaningful relief, it’s time to proceed to step 2.
This step keeps a low-FODMAP “background diet” and reintroduces individual FODMAP subgroups at a time to figure out which ones you tolerate well and which trigger symptoms.
This phase usually takes around 6–8 weeks. It’s important to increase your food choices to create your personal diet that includes a variety of nutrients.
Phase 3: Personalization
Now that we know the specific triggers of your IBS, the final phase is about building a long-term eating pattern that’s as varied and enjoyable as possible.
This usually means avoiding only what genuinely causes you trouble, rather than everything “FODMAP” in general.
What Not to Do on the Low-FODMAP Diet
After witnessing symptoms improve, reintroducing foods may feel risky and scary to some people.
As a result, some people decide to stay on phase 1: a low-FODMAP diet to avoid symptoms.
It is understandable as having symptoms might greatly affect the quality of life and our daily routine.
However, the low-FODMAP phase is intentionally designed to be short-term and restrictive. A long-term restrictive diet might lead to nutrient deficiencies and other complications that are bad for your health. (O’Keeffe M, 2017) (Martin, L, 2015)
A suitable reintroduction phase should be designed by a health professional, such as a dietitian, and should consider symptoms, client preferences, and food types.
In addition, the reintroduction phase should be gentle and progressive.
If symptoms return after a specific FODMAP subgroup, it should be re-evaluated or stopped. After that, in most cases, the client should wait until the symptoms are relieved before moving on to another FODMAP subgroup.
Important Limitations to Know About IBS and the FODMAP Diet
Research has backed the effects of the FODMAP diet to manage IBS. However, it’s not a magic fix for everyone. There are some realistic expectations worth going through.
- It doesn’t work for everyone. Around 20–40% of people don’t get adequate symptom relief from a low-FODMAP diet alone. (Eswaran SL, 2016) If that’s you, it’s not necessarily a failure on your part. Exploring other options rather than pushing on to Phases 2 and 3 might be a better approach.
- FODMAPs aren’t the only trigger. IBS often involves a generally sensitive digestive system, so food isn’t always the whole picture. Factors like stress or caffeine consumption could be examples of triggers.
- The low-FODMAP diet is not the right fit for everyone. If you have a history of disordered eating or are at risk of nutrient deficiencies, a highly restrictive elimination phase may do more harm than good. A gentler, more flexible approach is often more appropriate, and a dietitian can help you figure out what that looks like. (Martin, 2015)
Why Work With a Dietitian for IBS and FODMAP Diet Support?
This diet involves real nutritional trade-offs, a fair amount of complexity, especially in the reintroduction phase, and a process that’s genuinely easy to get wrong without guidance. A registered dietitian, ideally one with specific training in FODMAPs and IBS, brings:
- A solid understanding of nutrition, food, and how they interact with digestive health.
- Accountability to an evidence-based, ethical standard of care.
- The ability to translate “the science” into a plan that actually fits your life.
Related: Dietitian’s support for FODMAP
Beyond IBS and the FODMAP Diet: Other Tools Worth Knowing About
Food is a major piece of the IBS puzzle, but it’s rarely the only piece. Depending on your situation, other approaches that may help include: (McKenzie, 2016)
- Peppermint oil is a commonly used herbal therapy for IBS symptoms.
- Probiotics, which research suggests may offer modest benefits for some people (Brenner, 2009).
- Psychological therapies, such as gut-directed hypnotherapy and stress management techniques, which work through the gut-brain connection (Peters, 2016).
- Topical therapies and medications, used in some cases alongside dietary changes.
IBS and FODMAP Diet: The Bottom Line
While IBS is a common, frustrating disorder, it can also be manageable.
The low-FODMAP diet is one of the best-researched tools, but it’s a structured process, not a permanent restriction. It works best with the right guidance, realistic expectations, and an understanding that food is one piece of a bigger picture.
If your symptoms are getting in the way of your life, it may be a sign to get a formal diagnosis from your doctor and find the root cause or any underlying issues. During your IBS management, your dietitian is not only here to provide you with knowledge and education. They are also your companions throughout your journey and here to help you design a plan that suits you.
Conclusion
Should you feel you require personalized sessions for guidance of a dietitian for IBS and/or FODMAP diet support, book a free consultation or contact us for an appointment. As always if you have comments or questions, we encourage you to let us know.
References
1. Hungin, A.P., et al., The prevalence, patterns and impact of irritable bowel syndrome: an international survey of 40,000 subjects. Aliment Pharmacol Ther, 2003 17(5): p. 643-50.
2. McKenzie YA, Bowyer RK, Leach H, Gulia P, Horobin J, O’Sullivan NA, Pettitt C, Reeves LB, Seamark L, Williams M, Thompson J, Lomer MC; (IBS Dietetic Guideline Review Group on behalf of Gastroenterology Specialist Group of the British Dietetic Association). British Dietetic Association systematic review and evidence-based practice guidelines for the dietary management of irritable bowel syndrome in adults (2016 update). J Hum Nutr Diet. 2016 Oct;29(5):549-75. doi: 10.1111/jhn.12385. Epub 2016 Jun 8. PMID: 27272325.
3. Peters, S.L., et al., Randomised clinical trial: the efficacy of gut-directed hypnotherapy is similar to that of the low FODMAP diet for the treatment of irritable bowel syndrome. Aliment Pharmacol Ther, 2016. 44(5): p. 447-59.
4. El-Salhy, M., et al., The role of diet in the pathogenesis and management of irritable bowel syndrome (Review). Int J Mol Med, 2012. 29(5): p. 723-31.
5. Brenner, D.M., et al., The utility of probiotics in the treatment of irritable bowel syndrome: a systematic review. Am J Gastroenterol, 2009. 104(4): p. 1033-49; quiz 1050.
6. Oka P, Parr H, Barberio B, et al. Global prevalence of irritable bowel syndrome according to Rome III or IV criteria: a systematic review and meta-analysis. Lancet
Gastroenterol Hepatol 2020;5:908-917
7. Martin, L., van Vuuren, C., Seamark, L. (2015). Long-term effectiveness of short Chain Fermentable carbohydrate (FODMAP) restriction in patients with irritable bowel syndrome. Gut, 64: A51-A52.
8. Ahuja NK. A Case Study in the IBS-C Management Continuum: Assessing Patient Response and Tailoring Treatment. Gastroenterol Hepatol (N Y). 2024 Jul;20(7):383-427. PMID: 39206030; PMCID: PMC11348549.
9. O’Keeffe M, Jansen C, Martin L, Williams M, Seamark L, Staudacher H et al. Long-term impact of the low-FODMAP diet on gastrointestinal symptoms, dietary intake, patient acceptability, and healthcare utilisation in irritable bowel syndrome. Neurogastroenterology & Motility. 2017;30(1):e13154.
10. Martin, L., van Vuuren, C., Seamark, L. (2015). Long-term effectiveness of short Chain Fermentable carbohydrate (FODMAP) restriction in patients with irritable bowel syndrome. Gut, 64: A51-A52.
11. Eswaran SL, Chey WD, Han-Markey T, Ball S, Jackson K. A Randomised Controlled Trial Comparing the Low FODMAP Diet vs. Modified NICE Guidelines in US Adults with IBS-D. Am J Gastroenterol. 2016 Dec;111(12):1824-1832. doi: 10.1038/ajg.2016.434. Epub 2016 Oct 11. PMID: 27725652.
12. Gastroenterology Consultants of San Antonio. (n.d.). Low FODMAP diet & foods: Everything you need to know. Gastroenterology Consultants of San Antonio. Retrieved June 20, 2026, from https://www.gastroconsa.com/pati
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About Author:
Amélie Charron is a registered dietitian who who focuses her practice on women’s health, pediatric nutrition, weight management counselling and more.
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