Low-FODMAP Diet for IBS: Benefits & How to Do It

The low-FODMAP diet is an evidence-based treatment for IBS (irritable bowel syndrome), but it’s not for everyone. This diet restricts the consumption of “FODMAPs,” which are specific types of fermentable short-chain carbohydrates that can resist digestion.

“FODMAP” is an acronym for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols” which are all types of carbohydrates your gut bacteria convert to gasses. Examples of high-FODMAP foods are wheat, dairy products, onion, and garlic.

Following a low-FODMAP diet can help relieve IBS symptoms by eliminating the root cause of your IBS. If FODMAPs are causing bloating and diarrhea in your gut, avoiding FODMAPs should prevent bloating and diarrhea from occurring.

Provider note: We recommend a low-FODMAP diet to patients at the same time as a gut healing protocol. Our goal is to help you heal the root cause of gut problems, which means that some trigger foods you discover while following this plan may no longer trigger symptoms in the future. Whether it’s PrimeHealth or not, be sure to find a provider who will support you in the healing process so you ultimately have as few restricted foods as possible.

Unfortunately, certain patients may worsen IBS symptoms by following an IBS diet, particularly if the underlying cause of their IBS is SIBO (small intestine bacterial overgrowth). Talk to a provider with experience in SIBO about whether a low-FODMAP diet is right for you.

Also, some of my patients find the low-FODMAP elimination diet is simply too restrictive to successfully adhere to. If that’s the case for you, talk to your healthcare provider about an alternative that works to relieve your symptoms.

Keep reading for step-by-step instructions on effectively following a low-FODMAP diet for IBS.

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Weeks 1-4: Eliminate All High-FODMAP Foods

For the first 1-4 weeks (6 weeks, if you can) of a low-FODMAP diet, eliminate all high-FODMAP foods. It takes an average of 4 weeks for IBS symptoms to subside. Before the rest of this diet will work, you need to observe a significant reduction in your symptoms.

This diet also doesn’t work if you only eliminate some high-FODMAP foods — you’ll need to eliminate all of them. Common high-FODMAP foods to avoid include wheat, milk, onion, garlic, apples, beans, and some artificial sweeteners.

During this “elimination phase” or “restriction phase,” your IBS symptoms should go away. If your symptoms do not go away, talk to your doctor about other possible causes of your IBS symptoms.

Read more: What Is Irritable Bowel Syndrome?

Weeks 5-15: Reintroduce FODMAP Foods One at a Time

After the initial elimination phase, weeks 5-15 are the “reintroduction phase,” during which you reintroduce certain FODMAP foods one at a time. Then, you can observe which FODMAP foods result in symptoms. Each body is different, which is why each person will have a slightly different set of trigger foods.

When you reintroduce a new food, eat a normal portion twice a day for 1-2 days, then wait another 1-2 days before reintroducing another food.

Don’t reintroduce two foods at once, as that will interfere with the results of this elimination diet. You’re trying to figure out exactly which food(s) you need to eliminate permanently.

If, in those few days, when you reintroduce a food, IBS symptoms flare up, note which food(s) led to which symptoms. Let your doctor or health coach know right away.

Remember, if you do the work of healing your gut, it’s possible some trigger foods can be added to your diet in the future. Some foods may need to be permanently removed from your diet, but the purpose of this diet is to relieve your symptoms temporarily and heal the root cause of your gut problems.

This phase typically takes 6-10 weeks.

Week 16+: Maintain & Adjust As Needed

The “personalization phase” is the final part of a low-FODMAP diet. You should now be equipped to maintain your gut health and, after consulting your doctor or dietitian, adjust your diet as needed.

Keep an eye out for IBS symptom flare-ups: cramping, gas, diarrhea, or constipation. If you find symptoms returning, talk to your healthcare provider right away to adjust your new meal plan.

Our goal when developing a permanent meal plan for patients is to include FODMAPs that didn’t result in flare-ups but exclude FODMAPs that create issues. As we’ve stated above, this dietary plan should be done in conjunction with a gut healing protocol, allowing you to introducing previously-triggering foods over time and expanding your food list.

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High-FODMAP Food List

Here are the high-FODMAP foods that you should avoid at all costs during the low-FODMAP diet:

• Onions
• Garlic
• Wheat
• Barley
• Rye
• Cereals
• High-lactose products (in milk, ice cream, and soft cheese)
• Dried fruits
• Apricots
• Apples
• Avocados
• Cherries
• Nectarines
• Pears
• Plums
• Ripe bananas
• Watermelon
• Artichokes
• Cauliflower
• Leek bulbs
• Beans
• Soybeans
• Chickpeas (therefore hummus)
• Lentils
• Legumes
• Cashews
• Falafel
• Pistachios
• Split peas
• Wasabi
• Chai tea
• Chamomile tea
• Oolong tea
• Dark wines
• Rum
• Xylitol
• Sorbitol
• Mannitol
• Isomalt
• High fructose corn syrup
• Agave nectar
• Honey

I recommend that my patients download an app so you can look up high-FODMAP foods when you’re out to eat, shopping for groceries, etc. Quality FODMAP apps include:

• Fast FODMAP Lookup & Learn (Apple App Store / Google Play)
• Low FODMAP Diet A to Z (Apple App Store / Google Play)
• IBS Coach: FODMAP Diet Planner (Apple App Store / Google Play)
• Cara Care: FODMAP Tracker (Apple App Store / Google Play)
• FODMAP Helper – Diet Companion (Google Play)
• Monash University low FODMAP app (Apple App Store / Google Play)

Low-FODMAP Food List

Here is a (non-exhaustive) list of safe low-FODMAP foods you can eat when following a low-FODMAP diet:

• Unprocessed meats (most meats other than sausage)
• Seafood
• Eggs
• All fats and oils
• Butter, in moderation
• Hard cheeses
• Aged softer cheeses, like brie and Camembert
• Lactose-free milk, such as almond milk or rice milk
• Most spices, besides onion or garlic
• Lemons and limes
• Blackberries
• Blueberries
• Grapefruit
• Strawberries
• Oranges (not juice)
• Red and green peppers
• Cantaloupe
• Carrots
• Chives
• Kiwi
• Leek leaves
• Parsnips
• Zucchini
• Pickled gherkins (no onion or garlic)
• Lettuce, arugula, collard greens, and spinach
• Tomatoes (as long as you’re not nightshade-sensitive)
• Green beans, in moderation
• Corn and corn products (not high fructose corn syrup)
• Quinoa
• Rice
• Seeds
• Coffee (no dairy additives)
• Green tea
• Clear spirits (such as gin and vodka)
• Water

Benefits of a Low-FODMAP Diet

The benefits of a low-FODMAP diet may include:

• Reduced abdominal pain
• Less bloating and cramping
• Reduced flatulence
• Less frequent diarrhea or constipation
• Reduced fatigue
• Lower anxiety and depression
• Higher quality of life
• Peace of mind that you know what causes your IBS symptoms

Latest Research and Findings on the Low-FODMAP Diet

While the theory behind the low-FODMAP diet is not new, research on its effectiveness in managing irritable bowel syndrome (IBS) symptoms is ongoing.

A 2016 meta-analysis published in the Clinical and Experimental Gastroenterology evaluated multiple clinical trials and found that approximately 86% of IBS patients experienced significant symptom improvement on a low-FODMAP diet. Symptoms such as bloating, abdominal pain, and diarrhea were particularly well-managed.

Impact on Gut Microbiome

While the low-FODMAP diet is effective in reducing symptoms, it can also influence the gut microbiome. Studies show they can lead to a reduction in beneficial gut bacteria, such as Bifidobacteria. However, there are no obvious effects on the diversity of the other

Long-Term Effects

Long-term adherence to the low-FODMAP diet has both benefits and challenges. A 2023 clinical trial tracked IBS patients over two years and found that those who followed the diet experienced sustained symptom relief. 70-89% of these patients also stated they were satisfied with the low-FODMAP diet for managing their IBS symptoms.

Common Mistakes When Following a Low-FODMAP Diet

While we’ve covered the basics of the low-FODMAP diet, there are a few common mistakes that people make when following this diet. These include:

Not Fully Eliminating High-FODMAP Foods

It’s important to remove all high-FODMAP foods during the restriction phase because even small amounts can trigger symptoms. If you don’t eliminate them completely, it can be hard to know what’s causing discomfort, and your symptoms might not improve as expected. This can make the process frustrating and leave you feeling like the diet isn’t working.

Reintroducing Foods Incorrectly

When it comes to reintroducing foods, taking your time is key. If you rush or try multiple foods too close together, it can be difficult to tell which ones are triggering symptoms. This can lead to confusion and make it harder to identify which foods work for your body. Following a spaced-out and organized approach helps set you up for success.

Overlooking Hidden FODMAPs

Many everyday products, like sauces, condiments, and processed foods, can contain hidden FODMAPs. These sneaky ingredients can unknowingly cause symptoms, even if you think you’re following the diet carefully. Reading labels and being mindful of these hidden sources can make a big difference. Remember, it’s normal to feel overwhelmed at first, but with practice, it gets easier!

Low-FODMAP Diet for Specific IBS Types

Besides the general low-FODMAP diet, there are also variations that may be more suitable for certain types of IBS. These include:

IBS-C (Constipation)

If you experience constipation as part of your IBS symptoms, a low-FODMAP diet can help by reducing certain fermentable carbohydrates that may trigger bloating and discomfort. While a low-FODMAP diet doesn’t directly treat constipation, it can ease the overall strain on your digestive tract that often accompanies it.

To help, focus on low-FODMAP foods that are rich in fiber, such as kiwis, oats, or small servings of canned lentils, which can gently support your bowel movement. Meal ideas could include oatmeal topped with fresh strawberries or a quinoa salad with roasted veggies and olive oil. Remember to stay hydrated and consider how your body reacts to each adjustment.

IBS-D (Diarrhea)

For those dealing with diarrhea as part of IBS, a low-FODMAP diet can be particularly helpful in reducing urgency and frequent bowel movements. By avoiding high-FODMAP foods that may ferment in the gut and trigger diarrhea, you might notice more stability.

Focus on soothing, easy-to-digest meals like grilled chicken with rice and steamed carrots or a low-FODMAP vegetable soup. Eating smaller, frequent meals can also make a difference. Be patient with yourself as you figure out which foods work best for you—it’s all about creating comfort and balance.

IBS-M (Mixed)

If your IBS symptoms alternate between constipation and diarrhea, finding the right balance can be tricky but manageable with a low-FODMAP approach. The key is flexibility—adjusting your meals to suit how your body feels on a given day.

For example, on days when constipation is an issue, include higher-fiber, low-FODMAP foods like chia pudding made with almond milk. On days when diarrhea is more prominent, lean toward gentle options like baked salmon with mashed potatoes. Listening to your body and keeping a food diary can help you notice patterns and adapt your meals accordingly. It’s all about finding what works best for your unique symptoms so you can feel more in control of your digestion.

Common Challenges and How to Overcome Them

You may face some challenges while following a low-FODMAP diet, but don’t let them discourage you. Here are some common obstacles and tips to overcome them:

Dealing with Social Situations

Navigating the low-FODMAP diet while dining out or attending social events can feel overwhelming, but it’s absolutely doable! Start by checking the menu ahead of time if you’re eating out—most restaurants share their menus online, which gives you a chance to plan your meal before you arrive.

Don’t hesitate to ask the waiter about the ingredients or request small changes to make a dish work for you. If you’re attending a social event, consider bringing a dish you know is low-FODMAP to share with everyone—this way, you’ll know there’s at least one safe option for you.

Communication is key, so let your host know about your dietary needs; most people are happy to accommodate! Remember, it’s okay to prioritize your health—it’s all about finding the balance that works for you.

Staying Motivated During the Elimination Phase

The elimination phase can be tough, and it’s normal to feel frustrated at times. But remember, this phase is temporary and is designed to help you learn what foods work best for your body. To stay motivated, focus on the positives—many people experience significant relief from their symptoms during this phase, which can be incredibly encouraging.

Keep track of your progress in a food diary so you can see how far you’ve come. Plan your meals ahead of time to avoid feeling stuck or overwhelmed, and don’t be afraid to lean on your support system, whether that’s friends, family, or a healthcare professional.

Celebrate small wins along the way, even if it’s just making it through a challenging day. You’re taking important steps for your health, and that’s something to be proud of!

FAQs

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So we listen. We identify the underlying problem. And we treat that specific underlying cause. That’s why we have so many success stories.

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Sources

Morariu, I. D., Avasilcai, L., Vieriu, M., Lupu, V. V., Morariu, B. A., Lupu, A., … & Trandafir, L. (2023). Effects of a Low-FODMAP Diet on Irritable Bowel Syndrome in Both Children and Adults—A Narrative Review. Nutrients, 15(10), 2295.

Staudacher, H. M., Whelan, K., Irving, P. M., & Lomer, M. C. (2011). Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome. Journal of human nutrition and dietetics, 24(5), 487-495.

Kortlever, T. L., Ten Bokkel Huinink, S., Offereins, M., Hebblethwaite, C., O’Brien, L., Leeper, J., … & Gearry, R. B. (2019). Low‐FODMAP diet is associated with improved quality of life in IBS patients—a prospective observational study. Nutrition in Clinical Practice, 34(4), 623-630.

Cox, S. R., Lindsay, J. O., Fromentin, S., Stagg, A. J., McCarthy, N. E., Galleron, N., … & Whelan, K. (2020). Effects of low FODMAP diet on symptoms, fecal microbiome, and markers of inflammation in patients with quiescent inflammatory bowel disease in a randomized trial. Gastroenterology, 158(1), 176-188.

Halmos, E. P., Power, V. A., Shepherd, S. J., Gibson, P. R., & Muir, J. G. (2014). A diet low in FODMAPs reduces symptoms of irritable bowel syndrome.Gastroenterology, 146(1), 67-75.