When the Low-FODMAP Diet Doesn't Work

5 Steps to Take Next

green fruits and vegetables
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The low-FODMAP diet was developed as a way to offer people who have IBS a dietary approach for managing the disorder. Research has consistently shown that the diet can be quite effective in significantly reducing symptoms, particularly when the diet is undertaken under the supervision of a qualified dietary professional. The good news is that approximately 75 percent people who attempt the diet achieve diet success.

This is not such good news if you are someone who falls into that other 25 percent.

If that has been your experience, you are probably feeling very confused, frustrated, and thinking that once again nothing you seem to do for your IBS seems to help. Let's talk about what might have gone wrong and some things that you can try to get your symptoms under better control.

What Went Wrong?

Before you look into alternative treatments approaches, take a moment to think about whether or not you had the necessary conditions in place to optimize your chances for success on the diet. Here are a few things for you to consider:

1. Did you work with an appropriately trained dietary professional? All the participants in all of the research studies on the use of the diet as a treatment for IBS received direct supervision from a dietitian who was well-versed in the diet. Such a professional can ensure that not only do you adhere to the strict restrictions of the diet, but that you are also eating well-balanced meals and getting in all of the important nutrients.

2. How well did you do adhering to the diet guidelines? The low-FODMAP diet can be quite challenging to follow. For best results you should go through a full elimination phase, in which you avoid all foods that are high in FODMAPs and only eat foods that are low in FODMAPs. What makes the diet so challenging is that many common foods contain high-FODMAP ingredients such as wheat, garlic and onions.

If you took a casual approach to following the diet, or had a lot of "slips", you may not have provided yourself with the conditions necessary for optimal symptom improvement. If this is the case for you, you may want to give the diet another try, with a firm commitment and focus on strictly following through on the elimination phase of the diet.

3. Did you try long enough? As of now, research has not identified exactly how long one should be on the diet in order to enjoy diet success. Researchers at Monash University, where the diet originated, recommend that the elimination phase last for two to six weeks. If you are not experiencing significant symptom relief but have been on the diet for less than six weeks, you may want to try a little longer to see if a few more weeks of restricting high-FODMAP foods from your diet makes a difference in terms of your response to the diet.

What to Try Next

If you worked with an appropriate dietary professional, adhered strictly to the requirements of the elimination phase, and kept it up for a good six weeks and still saw little improvement in how you feel, give yourself a pat on the back for trying your best.

Do not spend a second blaming yourself - even in laboratory conditions, the diet just does not work for every person who has IBS. Here are some other options that you can look into to find symptom relief:

1. Talk to Your Doctor

Maybe your motivation to give the diet a try was to try a "natural" approach and to avoid taking medications for your symptoms. If that is the case, it might be time to make an appointment with a gastroenterologist to find out what medical options are available to you. Over the past few years, several medications have come on the market with FDA approval for the treatment of IBS. Your doctor will make a full assessment of your symptoms and may choose to offer you a prescription that they think would be of help to you.

2. Ask Your Doctor to Rule Out SIBO

SIBO (small intestinal bacterial overgrowth) has been found to be a contributing factor to symptoms in a sub-set of people who have IBS. One possible telltale sign of the presence of SIBO is that your symptoms occur within 90 minutes of eating.

The condition is diagnosed through the use of a hydrogen breath test. In order for the test to be accurate, you need to return to eating foods that are high in FODMAPs, as the low-FODMAP diet runs the risk of sending the bacteria into temporary dormancy. If the breath testing confirms that SIBO is present, your doctor may choose to treat you with one or several rounds of antibiotics. These specific antibiotics are unlike antibiotics you may have taken in the past, as they act predominantly in your small intestine to reduce the number of bacteria that may be present there. Because of this local effect, they typically do not cause many side effects and have little to no effect on the beneficial bacteria within your large intestine.

3. Ask Your Doctor to Rule Out Other Health Problems

One reason the FODMAP diet may not work is that you may have not have IBS, but actually have another disease. Ask your doctor to do a full workup or go to a specialist. Other possible diagnoses include:

4. Work With Your Dietary Professional

If you weren't already utilizing the services of a dietary professional, now might be the time to do so. And if you did work with such a professional and felt a good sense of rapport, it might be beneficial to continue on. Your dietary professional may help you to identify if there are any factors contributing to your poor response to the diet and help you to problem-solve strategies to address these other possible symptom contributing factors. Such a professional can also help you to determine which foods are best tolerated by you, while taking into account your complete nutritional requirements, as you seek out alternative forms of IBS treatment.

4. Identify Other Possible Food Triggers

FODMAPs are carbohydrates found in common foods that have been scientifically shown to contribute to IBS symptoms. However, this does not meant they are not the only foods that might trigger unwanted digestive symptoms. On your own, or working alongside a dietary professional, you may want to try following an elimination diet that targets foods that have a reputation for being IBS triggers. You will see that some of the foods on the list are foods that you may have already eliminated when you were following the low-FODMAP diet. The foods most typically recommended for restriction are:

  • Alcohol
  • Coffee and other caffeine-containing drinks
  • Corn
  • Dairy
  • Eggs
  • Gluten
  • Soy

Although some sugar is allowed on the low-FODMAP diet due to the way that our bodies digest it, you may find that your body does not tolerate sugar well. As challenging as it may be, you may want to try an elimination of foods containing added sugar and assess what effect that may have on your symptoms.

Fried foods, greasy foods, and large meals can all be hard on your digestive tract. You may feel better if you eat smaller meals throughout your day (although a large breakfast may help to ease constipation). Avoid fatty junk foods and be sure to eat foods that contain healthy fats.

Last, you may want to talk to your doctor about being assessed for true food allergies, which are immune system (as opposed to digestive system) reactions to certain foods. One of the more common ones include a reactivity to casein, a protein found in milk and dairy products. Although the low-FODMAP diet restricts foods that are high in lactose (milk sugar), it does not restrict the use of lactose-free dairy products which do contain casein.

5. Try a Mind/Body Treatment

It may be that there are factors beyond food that are contributing to the severity of your symptoms. Stress, of course, can be a major trigger for digestive symptoms. Mind/body treatments may be helpful in calming your system and providing you support as you deal with the stress associated with having IBS itself. Cognitive behavioral therapy (CBT) and hypnotherapy are two types of mind/body treatments that have research support as effective IBS treatments.


Ford, A., et.al. "American College of Gastroenterology Monograph on the Management of Irritable Bowel Syndrome and Chronic Idiopathic Constipation" American Journal of Gastroenterology 2014 109:S2-S26.

Nanayakkara WS, Skidmore PM, O’Brien L, Wilkinson TJ, Gearry RB. "Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date." Clinical and Experimental Gastroenterology 2016;9:131-42.

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