What's a Low FODMAP Diet?
A quick note from us
With over 80% of people with irritable bowel syndrome (IBS) reporting food-related symptoms, S and greater than 60% saying they’ve made diet changes to manage their symptoms S, we’re gonna hedge our bets here and say that our friends with IBS have scoped out their fair share of IBS diet strategies. And if you’ve ever entered the terms “diet” and “IBS” in the same search engine cue, then you’ve undoubtedly come across a peculiar-sounding diet for IBS called the low FODMAP diet.
That’s for good reason. Out of all diet strategies out there aimed at improving IBS symptoms, the low FODMAP diet is the most studied and appears to be the most effective diet for IBS symptom management. S If that sounds exciting and promising, it is, but we’ve gotta be honest and emphasize that a low FODMAP diet is challenging to pull off.
And that’s exactly why we’re here…
We’ve seen the overwhelming low FODMAP diet lists and resources out there, and we’ve encountered more than one insufficient low FODMAP diet handout that was never designed to cover the role of a specialized registered dietitian. We’ve gone to bat with the low FODMAP diet personally and professionally, and we want you to breathe a huge sigh of relief because we’ve got ya covered.
Our purpose here is to give you the knowledge and tools necessary to steer you towards the professionals and resources you’ll need in order to pull off the low FODMAP diet (if it’s appropriate for you to do so).
Here, we’ve covered the basics, including:
- What a low FODMAP diet is
- How the diet works
- Who it’s for
- The pros and cons
- And common misconceptions about the diet
We’ve also explained each key step you’ll need to take if you’re embarking on a low FODMAP diet. And not to worry, we won’t just be talking about the diet. We’ve taken things a step further by developing several helpful tools linked throughout this guide. Our goal behind these tools is to help you pull off the most seamless low FODMAP diet trial possible. So without belaboring our purpose here any further, let’s dive right in…
If you’re anything like us, the first time you heard of a low FODMAP diet, your response was likely something along the lines of, “FOD-what??” To add clarity to the term “FODMAP,” it helps to understand that the name comes from an acronym. And contrary to popular belief, the acronym does not stand for “Frustrating, Oppressive, Dietary Method to Activate Pessimism.” Rather, it stands for “Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols.”1 The names in the acronym are the technical terms for several groups of small fermentable carbohydrates, which are made up of 1 to 10 sugars and are indigestible or not absorbed well in the gut.2
What’s a Low FODMAP diet?
A low FODMAP diet is a 3-phased plan which restricts, challenges, and then reintroduces FODMAPs according to your personal tolerance. Common sources of fodmaps include certain fruits, vegetables, legumes, grains, honey, sweeteners, milk, and certain dairy products (see table below).2 Undergoing a low FODMAP diet can potentially help folks with IBS to get a better handle on their symptoms and to gain awareness about which specific FODMAPs may be triggering symptoms. The diet’s end goal is to maintain IBS symptom control while also expanding food options as much as possible.
Examples of FODMAPs and their primary sources
|Oligosaccharides (GOS*, Fructans)||Found predominantly in legumes/beans/pulses, wheat, rye, onions, and garlic|
|Disaccharides (Lactose)||Found in dairy products such as milk, soft cheese, and yogurts|
|Monosaccharides (excess Fructose)||Found predominantly in foods such as honey, apples, pear, mango, figs, and high fructose corn syrup|
|Polyols (e.g., sorbitol and mannitol)||Found in some fruits and vegetables and added to diet products (e.g., hard candies, gum, soft drinks)|
How Does a Low FODMAP Diet Work?
The bottom line is that FODMAPs in the diet can worsen IBS symptoms by causing some “plumbing issues” in the bowels. For example, some FODMAPs pull water into the intestine through a process called osmosis. Others aren’t digested and make it to the large intestine, where they’re fermented by bacteria, which leads to gas production.1 When the gut is distended by water and/or gas, this can worsen abdominal pain and bloating in sensitive individuals. Gas, water, and distention may also lead to problems with gut movement and bowel symptoms such as diarrhea, constipation, or a mixture of both. Overall the low FODMAP works by restricting dietary FODMAPs in order to reduce intestinal water and gas, which helps to lessen IBS symptoms.
↑FODMAPS → ↑ Intestinal Water &/or Gas → ↑ IBS Symptoms
Who Should and Shouldn’t Follow a Low FODMAP diet?
Factors to consider
There are so many factors that go into determining if a low FODMAP diet is appropriate for you, but ultimately the judgment call to embark on the diet is best made between you, a qualified physician, and an overseeing registered dietitian trained in the diet’s implementation.
A deeper look at your medical, psychological, and diet history before taking on a low FODMAP diet is a must. For example, have you been appropriately screened for and diagnosed with IBS by a qualified medical provider? This is a crucial step because there are many conditions that can mimic symptoms of IBS but that require a totally different medical or diet therapy for management (more on that later).
It’s also important to assess if your symptoms are triggered more often by diet, psychological stress, or both. Depending on your primary symptom triggers, it may be necessary to involve (or even prioritize) care from mental healthcare providers.
Even after you have a diagnosis of IBS and your symptom triggers have been assessed, you still aren’t in the clear to take on the diet. A skilled dietitian will need to conduct an assessment to see if it’s medically appropriate for you to be on a more restrictive diet.
Sometimes simpler diet strategies — such as a simplified version of a low FODMAP diet — may or may not be ideal for you based on your willingness to follow a restrictive diet, your diet history, and your personal risks of malnutrition. Below are some general considerations that you and your healthcare providers will want to keep in mind before taking the nuclear option and tackling a full 3-phased low FODMAP diet.
Signs you may be a candidate for a low FODMAP diet trial
Signs that a full low FODMAP diet may not be right for you
Pros & Cons of the Low FODMAP Diet
The low FODMAP diet comes with some pretty significant pros and cons. On one hand, the diet is the most studied and validated diet for IBS symptom management. Clinical studies have found adequate symptom relief for 50-80% of IBS sufferers during phase 1 of the diet.3 As promising as that may be, the reality is that up to 20-40% of people with IBS will not experience adequate symptom relief on a low FODMAP diet.3
The diet is also highly restrictive during the elimination phase and may be overwhelming, confusing, and expensive to follow. Adding to this, it can be hard to achieve adequate nutrient intake without proper planning. The diet can reduce dietary fiber consumption, meaning that special care is needed to ensure enough FODMAP-friendly fiber is eaten on the diet, particularly for those with constipation.2 Other areas of concern include trouble with getting in enough calories and the potential for lower calcium and iron intake on the diet.2
It’s also imperative to point out that a strict low FODMAP diet should not be followed over the long term due to the potential for harmful effects on the gut microbiota ( i.e., a decrease in helpful gut microbes).2 With all of these potential cons, you should never go it alone with a low FODMAP diet. We’d actually encourage you to think of a DIY attempt at a low FODMAP diet without professional oversight as the diet equivalent of doing your own electrical wiring when you’re not an electrician.
What the Diet is NOT: Common Misconceptions
As dietitians, we come across a lot of misconceptions surrounding anything and everything that has to do with nutrition, and the low FODMAP diet is no exception. While we couldn’t even begin to tackle all the misconceptions out there about this diet, there are a handful that we’d like to scream from the rooftops that we’ve discussed a bit further below:
1. The Strict Phase of the Diet is NOT intended to be long-term
The strict low FODMAP diet followed during phase 1 is only followed for 2-6 weeks and for portions of phase 2 of the diet, which lasts for 6-8 weeks. Permanent elimination is not the goal. A balance between symptom management and a broad and diversified diet is the end goal.
2. This diet does not treat or assess for food allergies
FODMAPs are not allergens; they’re small carbohydrates. In sensitive individuals, they cause discomfort due to how they impact the “plumbing” of the bowels. On the other hand, allergens cause symptoms by provoking an immune response.
3. FODMAPs are not inherently “unhealthy"
Many FODMAPs come from very healthy foods. Even FODMAPs themselves may act as prebiotics or “food” that helps to feed our good gut bacteria. However, these carbohydrates can still be poorly tolerated and lead to uncomfortable symptoms in sensitive individuals. The low FODMAP diet’s end goal is to eventually add in as many healthful FODMAP-containing foods as possible while still maintaining control over IBS symptoms.
4. A low FODMAP diet is not a gluten-free diet
Gluten is a protein, whereas FODMAPs are carbohydrates. Many gluten-free foods are eaten or recommended on the diet, not because of the gluten content but because higher FODMAP content is found in many gluten-containing foods. Some gluten-containing foods, such as sourdough spelt bread, are low in FODMAPs and can be eaten on the diet.3 With this understanding, because a low FODMAP diet can inadvertently reduce gluten intake, it’s all the more important to have your IBS diagnosis in hand before starting a low FODMAP diet. Celiac disease – an autoimmune disease triggered by gluten consumption – can mimic some symptoms of IBS, and should be ruled out based on screening tests and/or your physician’s best judgment about your symptoms during the IBS diagnosis process. Getting a celiac diagnosis requires sufficient gluten intake for a set period of time. So know that undertaking a low FODMAP diet without having ruled out celiac disease may inadvertently lead to a missed diagnosis of the condition down the track, with reduced gluten consumption on a low FODMAP diet possibly leading to a false negative screening result.
How To Do The Low FODMAP Diet (Action Plan)
Now that we’ve covered some of the basics behind what a low FODMAP diet is, the next part is where we talk about how exactly to pull off a low FODMAP diet. To do this, we’ve covered 6 crucial steps for implementing the diet from start to finish.
The first two steps include:
- Finding a professional – This is how you confirm a low FODMAP diet is right for you, and where we’ll talk about how to find the right professional to oversee your low FODMAP diet trial.
- How to build your low FODMAP diet toolkit – Here, we point you in the direction of implementation tools you’ll want in your arsenal before taking on a low FODMAP diet.
And finally, we’ll cover the phases of the diet including:
- Phase 1 of the diet: the low FODMAP diet
- Monitoring your response to the diet
- Phase 2 of the diet: FODMAP Reintroduction
- Phase 3 of the diet: Personalization
Step 1: Finding a Professional
Going it alone may seem intriguing for the sake of saving money or avoiding potentially embarrassing conversations about your bowel symptoms. But as we mentioned before, it’s crucial to seek proper medical guidance before trying a low FODMAP diet. That’s because multiple medical diagnoses can result in symptoms that look pretty similar to IBS. Some of the conditions that can mimic IBS symptoms include:
- Thyroid disorders
- Celiac disease
- Inflammatory bowel disease (Crohn’s disease and Ulcerative colitis)
- Pelvic floor disorders
- Pancreatic exocrine insufficiency
- Bowel cancers
- Bile acid malabsorption.
Getting appropriate medical guidance is so important, because the right diagnosis facilitates the right form of treatment. Starting a low FODMAP diet without medical guidance and proper testing could be a setup for a missed diagnosis with unfortunate health consequences, and even further delays in symptom relief.
Once you have a diagnosis from your physician, you’ll then need to be referred to an experienced dietitian trained in implementing a low FODMAP diet. If you or your physician are unsure about which dietitian’s in your area have undergone training to appropriately apply a low FODMAP diet, we suggest referencing the Monash University directory of Dietitians to find an RD who can assist you with low FODMAP diet implementation.
A Note About Monash University
Monash University is based out of Melbourne, Australia. This institution initially developed the low FODMAP diet protocol and multiple resources that aid in implementing the diet. They also provide education to dietitians throughout the world who undergo their course to learn how to implement a low FODMAP diet properly. Their directory includes dietitians who are knowledgeable about low FODMAP diet implementation.
Step 2: Build Your Low FODMAP Diet Toolkit
Monash University resources
After meeting with a professional, you’ll have a much better understanding of the low FODMAP diet principles. But still, this diet can feel overwhelming and is very hard to pull off without supplemental resources.
For that reason, we highly suggest using the Monash FODMAP app as a comprehensive resource for determining the FODMAP content of common foods. This app was developed by the Monash University research team. It’s available for Android and iOS devices and can be downloaded from the app store or Google play.
The Monash FODMAP App includes:
- General information about IBS and the low FODMAP diet
- Tutorials for using the app and for following the low FODMAP diet
- A food guide detailing the FODMAP content of hundreds of foods
- Low FODMAP recipes
- As well as food and symptom diaries
Digest Life resources
- First up is The FODMAP foods list– a list which contains the FODMAP content of several common foods. While this list is not as comprehensive as the Monash FODMAP app, it is a helpful tool for getting a quick overview of which foods have high, medium, and low FODMAP content. The list also details exactly which types of FODMAPs a specific food contains, and the doses in which those FODMAPs are no longer considered “low” in FODMAPs.
- Next, we suggest checking out our grocery-list making game changer – the Low FODMAP Diet Meal Planner. The goal behind this meal planner is to help you build a balanced low FODMAP diet that meets your nutrition needs. Here, we’ve broken down each food group, and provided details about several low FODMAP foods in each food group category that you can eat during more strict phases of the diet. We’ve also created suggested serving sizes for each food group based on your individual calorie needs. Be sure to also check out the ideas we’ve included for low FODMAP flavoring swaps, and the list we’ve provided here of high FODMAP ingredients to look out for in packaged foods.
- Keeping in line with our goal of helping you to plan a healthy and nutritious low FODMAP diet, we’ve also created a list of low FODMAP high fiber foods. As we mentioned before, getting in enough fiber can be tricky on a low FODMAP diet, so our goal with this resource is to help you bridge the fiber gap that so often goes hand-in-hand with a low FODMAP diet.
- Another challenging aspect of the diet is sorting out how to go about reintroducing FODMAPs one at a time to test your tolerance. While the reintroduction process can look different from one person to the next, we’ve created a Sample FODMAP Reintroduction Schedule, complete with suggested foods and serving sizes for you to test during the reintroduction phase.
And finally, we’ve also put together a Simplified Low FODMAP Diet Handout. This resource is for the folks out there who may not need a full-fledged low FODMAP diet, but who still have sensitivities to particularly high FODMAP foods. Of course, you’ll want to work with your dietitian to ensure you’re a good candidate for this approach based on your personal history.
Step 3: Phase 1 – The Low FODMAP Diet
The first phase of a full low FODMAP diet is the most restrictive phase. This is where foods that contain high and moderate amounts of FODMAPs are swapped with low FODMAP alternatives. The goal during phase 1 is to find out if FODMAP sensitivities are present and to relieve IBS symptoms.
What Counts as Low FODMAP?
The work of quantifying the amount of FODMAPs in different foods has mostly been done by Monash University – the institution where the low FODMAP diet originated. Monash University has developed set cut-off values for each type of fermentable carbohydrate which qualifies as a FODMAP. The cut-off thresholds differ from one FODMAP to the next for what counts as being “low” in FODMAPs. While we’ve included those numerical cut-off values below for the sake of completeness, these numbers are likely more confusing than helpful. The good news is that Monash University has simplified this information via their app, where they’ve created a traffic light system to offer guidance about which foods contain low, moderate, and high amounts of FODMAPs.
Using the traffic light system is the only way to adhere to a low FODMAP diet
There is no other way to quantify the amount of FODMAPs in each food, as Monash University has only published numerical FODMAP data for some foods in the scientific literature. S,S,S,S They also have not made their cut-off values for moderate and high FODMAP content publicly available.8
For those of you who prefer more precision, not having numerical values to tally up your daily FODMAP intake may feel frustrating, but the good news is that a low FODMAP diet is not a perfect science and is mostly designed to get FODMAP intake into a daily range where symptoms are better controlled. A low FODMAP diet appears to induce symptom control when total FODMAP intake is reduced from the average of 16-30 grams of FODMAPs per day on a typical diet down to 3-18 grams per day on a low FODMAP diet.1 This means it’s actually not necessary (or even possible) to eliminate FODMAPs completely. The goal is just to get them low enough so that they aren’t provoking symptoms.
Also, take comfort in knowing that FODMAP thresholds were set conservatively to allow people to include more than one serving of low FODMAP (green) foods at each meal.8 So, for the purpose of getting into that general well-tolerated range, a simplified traffic light system should do the trick without stressing over the more technical numbers we’ve provided below.
For more details about which foods are high, moderate, and low in FODMAPs, we encourage you to check out the Monash FODMAP app and take a look at our FODMAP content list, which we’ve compiled using data from the app. Keep in mind that it’s not uncommon for different foods to be high in more than one type of FODMAP. There are also other factors that can alter the FODMAP composition of foods ranging from preparation and storage methods, ripeness, the part of a FODMAP-containing plant consumed, and growing conditions. 8
Technical Low FODMAP Cut-off Values
|FODMAP Group||Grams Per Standard Serving of an Individual Food|
(from grains, legumes, nuts, and seeds)
(from vegetables, fruits, and all other products)
|Polyols – Sorbitol or Mannitol||<0.20|
(in the absence of the sugar glucose)
Fructose in Excess of Glucose
(for fresh fruit and vegetables when fructose in excess of glucose is the only FODMAP present)
Table Source: 8
What’s the Duration of Phase 1?
The first phase of the diet lasts for 2-6 weeks. Studies often have observed symptom improvement in this phase of the diet, typically around weeks 3 to 4.1 Ultimately, the duration of phase 1 is something that will be determined between you and a qualified registered dietitian overseeing the diet’s implementation. Your dietitian will monitor for any diet application pitfalls and offer guidance on if and when you should proceed to the next phase of the diet based on your degree of symptom control. Above all else, remember that this phase of the diet is temporary and should not be undertaken permanently.
Need Some Meal Planning Help for Phase 1?
We totally understand! Making grocery lists, and getting a general idea of what you should and shouldn’t be eating during phase 1 is easily one of the hardest parts of implementing the diet. Just a reminder to check out our Low FODMAP Diet Meal Planner, The FODMAP foods list, and the High Fiber Low FODMAP Foods List as tools to help you implement and plan your meals for phase 1 of the diet in a balanced way.
Step 4: Assessing Your Response to the Diet
If you’re not experiencing relief of IBS symptoms during phase 1 of the diet, the first step is to troubleshoot with your dietitian. This diet can be hard to follow, but a pro can help you spot any application problems.
If that doesn’t work, you may not be a low FODMAP diet responder, which happens about 20-40% of the time.3 If you’re not experiencing symptom relief on a low FODMAP diet, your dietitian may have other helpful diet strategies to suggest.
It’s also important to keep expectations realistic. Some people will experience overwhelming relief from the diet, while others will have no relief or only mild relief. Some symptoms are normal, such as small amounts of gas or bloating.3
IBS symptoms can also fluctuate from mild to severe due to other outside factors such as stress, anxiety, menstruation, gastroenteritis, and physical activity. In some cases, referral to other health practitioners may be helpful, too — this may be especially true if gut symptoms are strongly tied to stress and anxiety.3
Most importantly, if no improvements have been experienced at the end of phase 1 of the diet, it is critical that you abandon the low FODMAP diet and not move on to phase 2 and 3. This means going back to your regular diet and no longer avoiding high FODMAP foods.7
Step 5: Phase 2 of the Diet - FODMAP Reintroduction (6-8 weeks)
During Phase 2, foods containing mostly one FODMAP subtype — not those containing multiple FODMAPs — are added in one at a time to see how each FODMAP group is tolerated.
The background diet remains low in FODMAPs, except for the tested food. 7
On day one, a portion of food is given in a moderate FODMAP dose. If this is well-tolerated, then a higher amount is given on day 2. Finally, the highest FODMAP dose is provided on day 3. 7 This sequential dosing helps to establish what’s called a “tolerance threshold” to certain FODMAPs. During each challenge, good record-keeping is essential to keep track of which foods are well tolerated, somewhat tolerated, and poorly tolerated.7 The Monash app has a useful record-keeping function. We’ve also created a simple log that can be used to track symptoms in our Sample FODMAP Reintroduction Schedule.
After each FODMAP challenge comes a 2-3 day washout period where you return to a strict low FODMAP diet to avoid the risks of any carryover effects on the next food challenge. You may suspect certain foods are potent triggers (e.g., onion or garlic). In that case, your dietitian may suggest doing test days every other day rather than 3 sequential days or eating smaller serving sizes.7 If you have a significant worsening of symptoms, your dietitian may recommend halting that specific challenge altogether and returning to a low FODMAP diet to help symptoms resolve. If a challenge is well tolerated, your dietitian may encourage you to challenge the FODMAP containing foods in larger servings or more often (e.g., twice daily).7
Anxiety can significantly impact gut symptoms and may lead to a “nocebo” effect. A “nocebo” effect happens when our anticipation of symptoms and discomfort actually results in negative symptoms in cases where we may not actually have a sensitivity to a given food or FODMAP. For this reason, a blinded food challenge can help when high amounts of food anxiety is present to discern real FODMAP intolerance from anxiety-related gut symptoms.7 If you’re anxious about reincorporating FODMAPs in your diet, it may be suggested to involve a family member or friend. The dietitian may instruct this individual on adding FODMAP-containing foods into your diet so that you aren’t aware they’ve been added.
It’s recommended to only eat meals prepared at home during testing days to ensure you have complete control over your diet’s FODMAP content.7 Once you’ve demonstrated tolerance to specific FODMAP categories, your dietitian may recommend trying combinations of previously tested FODMAPs to see if certain combinations trigger symptoms.7 For example, if you combined avocado with wheat toast to see if you can tolerate sorbitol and wheat fructans together.
We know this all sounds complicated, but we’ve created a Sample FODMAP Reintroduction Schedule so that you can get a feel for the reintroduction process. Your dietitian will tailor food challenges so that you’re testing foods that you eat most often. For example, you may not eat cauliflower very often, but perhaps you enjoy mushrooms. In that case, your dietitian might choose to test your mannitol tolerance with mushrooms instead of cauliflower. There is also no set order that the challenge needs to be carried out. It may be suggested to start with challenge foods you have missed the most or those you believe you are most likely to tolerate.7
Step 6: Phase 3 - Personalization
During phase 3 of the diet, you’ll discuss your challenge results with your dietitian to create a personalized diet framework. FODMAPs that did not trigger symptoms during phase 2 will be added back into your diet in moderate or high amounts without restriction.7 Low and moderate servings of somewhat tolerated FODMAPs may also be added back into the diet.7 If a FODMAP was poorly tolerated, then mostly low FODMAP servings should be eaten of FODMAP foods from that category.7 However, repeat challenges in the future are recommended to see if tolerance improves over time.7