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

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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.

At PrimeHealth in Denver, our friendly healthcare providers have helped hundreds permanently reverse their IBS. Take control of your gut health.

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:

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:


Will a low-FODMAP diet reverse IBS?

A low-FODMAP diet may reverse IBS temporarily. Once you finish this elimination diet, you and your provider can formulate a long-term diet plan with the aim of permanently reversing your IBS.

You can take other natural therapies, supplements, and preventive measures to prevent IBS symptoms.

Who should follow a low-FODMAP diet?

Only people with IBS should follow a low-FODMAP diet, and it may not be right for all IBS sufferers. Talk to your doctor or health coach about if the low-FODMAP diet is right for you.

This diet is not a weight loss diet. It’s for people diagnosed with IBS. Studies show that the low-FODMAP diet is safe and effective for IBS treatment.

Is a low-FODMAP diet safe if I’m pregnant?

A low-FODMAP diet is not recommended if you’re pregnant. Whether it’s safe is difficult to study, but most doctors agree that the baby should get whatever nutrition it needs.

If you finished the low-FODMAP elimination diet and are adhering to your personalized low-FODMAP diet (which is likely much less restrictive), talk to your medical provider about staying on that diet while you’re pregnant. In many cases, your personalized low-FODMAP diet will benefit you and the baby.

What are the FODMAPs?

FODMAPs stands for “fermentable oligosaccharides, disaccharides, monosaccharides and polyols.” Each of those words is described in detail below so you can better understand this diet:

  • Fermentable: Your gut bacteria convert certain compounds to gasses in a chemical process called fermentation.
  • Oligosaccharides: Soluble plant fibers (called “oligosaccharides” or “prebiotics”) feed the good bacteria in your gut. “Oligo-” means “a few,” so these sugars chemically consist of a few monosaccharides. Some people may confuse a sensitivity to oligosaccharides (such as fructans) with a gluten sensitivity.
  • Disaccharides: The primary fermentable disaccharide is lactose (milk sugar). “Di-” means “two,” so these sugars contain precisely two monosaccharides chemically linked together.
  • Monosaccharides: The chief fermentable monosaccharide is fructose (fruit sugar). Not all fruits are high FODMAP, but it’s best to consume fruits with caution. “Mono-” means “one,” so these simple sugars are single saccharides that cannot be broken down into smaller saccharides.
  • Polyols: These are sugar alcohols, often used as natural sugar alternatives. Polyols are naturally found in certain fruits. Your gastrointestinal tract cannot fully digest sugar alcohols, so you get the sweet taste without the calories. However, indigestible sugars may lead to IBS symptoms.

How long should I stay on a low-FODMAP diet?

The duration of a low-FODMAP diet is 8-16+ weeks:

  • 1-4 weeks of eliminating all FODMAPs until your IBS symptoms subside.
  • 5-10 weeks of reintroducing certain FODMAP foods to identify which foods result in IBS flare-ups.
  • At the end of the diet, you and your doctor form a less restrictive diet plan that avoids the FODMAP foods that give you problems. This permanent diet plan may include some FODMAPs that didn’t cause you problems.

If you’re also following a gut-healing protocol, like the one we recommend to our patients, you may be able to eventually reintroduce some foods that triggered you during the second phase of this diet. Ideally, you would no longer have to worry about FODMAP content and only have to remain aware of the few foods your body doesn’t play well with.

Got IBS? Get One-On-One Support.

At PrimeHealth, our functional health experts have helped hundreds of patients overcome their IBS. We understand it can impact your quality of life, job performance, and self-esteem.

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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  2. 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.
  3. 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.
  4. 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.
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