When the low FODMAP diet doesn't work - Goodness Me Nutrition (2024)

Have you tried the FODMAP diet but it didn’t work? Many of my clients come to me saying they’ve already tried several diets for IBS including dairy free, gluten free and the low FODMAP diet.

This is so frustrating, because it’s a well researched diet for IBS. But, in reality everyone’s symptoms and causes of IBS are different, so it makes sense there is not a single IBS diet that would work for everyone.

Contents

FODMAP doesn’t work for everyone

If you’re not familiar with the low FODMAP diet you can read my Beginner Guide to the Low FODMAP Diet .

Basically the low FODMAP diet excludes fermentable carbohydrates.

These found are in healthy common foods like apples, avocado, mushrooms or peaches. These aren’t foods everyone should stay away from by any means.

When researchers have tested whether removing FODMAPs from the diet of people with IBS, the results are generally quite positive. Evidence estimates around 50% to 86% of patients will feel better, averaging around 75% of people. So 3 out of 4 people will get relief from IBS symptoms by following a low FODMAP diet.

But what if you’re in the remaining 25%? And what happens when you bring the FODMAPs back into your diet?

What to do if your FODMAP diet isn’t working

The diet is quite hard to follow, so firstly let’s check you’re doing it right, before ruling it out.

If you’re following a low FODMAP diet but still don’t see improvement in your symptoms here’s what to consider:

  1. Check you’re following the FODMAP diet correctly

The low FODMAP diet isn’t a NO FODMAP diet, it’s reducing foods high in FODMAPS, but portion sizing is key.

  • Watch out for hidden FODMAPS (e.g. in sauces or ready meals)
  • FODMAP stacking is where you eat two moderate FODMAP foods in a meal and inadvertently make that meal high FODMAP. For example if you eat a moderate portion of artichokes (e.g. 70g) and then a moderate portion of red peppers (around 60g) which when eaten in the same meal could become a high FODMAP meal.
  1. Monitor your tolerance to portions

The portion sizes for deciding whether a food is high, moderate or low FODMAP were drawn up by the Monash University. I recommend downloading the app if you’re trying to follow a low FODMAP diet.

However, the rules for portions are based on food composition analysis in a lab.

Your digestive processes, genetics and environment will not match lab conditions.

Therefore you may be more, or less tolerant to the foods in a low FODMAP diet.

There is some trial and error expected in this process, even if you follow the diet to the letter, unfortunately it isn’t an exact science.

Let’s look now at why the diet might not suit your and you digestion.

Reasons the FODMAP diet might not work for you

1. FODMAPs aren’t the trigger of your IBS

There are many causes of Irritable Bowel Syndrome (I’ve written before about possible causes of IBS) and it isn’t always even related to food.

Stress is a major driver of digestive pains, and finding ways to manage your anxiety, worry and stress can have a huge impact on IBS.

As part of getting your IBS diagnosis hopefully your doctor ruled out other conditions which need medical attention. These can often be mistaken for IBS, and include inflammatory bowel disease, coeliac disease, diverticular disease and bowel cancer, among others.

If you haven’t yet seen a doctor, make an appointment to get these crossed off the list.

So what else could it be?

If you don’t think it’s stress, or another condition, and it’s food related there could be another trigger. There are compounds in foods which can cause a sensitive digestion to react with gas, pain, cramps or diarrhoea, such as

  • histamine (in aged foods like preserved meats, leftovers, fermented foods). I’ve written a longer blog about histamine and IBS you can read the details about how to do a low histamine diet.
  • salicylates (including oranges, berries, sweet potato, broccoli, tea, almonds)
  • alcohol
  • dairy
  • gluten
  • soy
  • corn

Some of these will be reduced in a low FODMAP diet, but many won’t be ruled out completely.

2. You are sensitive to pain

(This isn’t about not being strong enough, or weak in anyway.)

Visceral hypersensitivity (enhanced communication between your brain and gut) is present in up to 65% of people with IBS

We all get gas and bloating to some extent when we eat.

But, people without IBS don’t experience as much pain or sensitivity as you might, to normal aspects of digestion.

This extra sensitivity to gas and bloating is a common feature of IBS.

There are so many nerves in the gut if these are on high alert it may be triggering your pain response. Medication from your GP may be able to help with calming your nervous system.

Support the vagus nerve

In addition it is worth finding ways to manage your stress. The gut and brain are connected by the vagus nerve, and in times of stress it can affect digestion. Here is a good summary of the vagus nerve and how it can affect digestion.

You can support this key nervous pathway through activities such as:

  • Deep breathing – specifically focussing on long slow exhalations
  • Yoga – to promote strength of muscles, and learn breathing techniques
  • Cold water swimming – to ‘reset’ the vagus nerve communication
  • Laughing – relieves stress, reduces pain sensitivity and can help relax the diaphragm
  • Singing / chanting – the vibrations help to calm the body
  • Gargling – helps tone the muscles in the throat.

3. Your gut transit time is too fast

Food might be rushing through you too quickly, potentially due to a food intolerance (see above) where more water is pulled into the small intestine.

There is also a condition known as ‘dumping syndrome’ where your body secretes hormones that speed up digestion, causing a fast transit through the gut. This can be due to a lack of digestive enzymes affecting the speed of food through the small intestine, or it can be linked to diabetes.

Some people find adding foods like psyllium husk, flaxseeds, chia seeds to their diet can help form a more solid stool.

4. Slow bowel transit time

If food takes a really long time to move through your digestion there is a potential for bacteria to overgrow. This can cause symptoms of IBS like bloating, excess gas, and irregular bowel movements, due to bacteria which starts to grow during the slow passage of food. This is sometimes refered to as Small Intestinal Bacterial Overgrowth.

A slow transit time won’t always look like constipation, you could have a bowel movement every day, but still have a slow transit time.

5. Gut Dysbiosis

We don’t have a blueprint for a healthy gut, but we do know that some bacteria are more associated with digestive issues, and others with good health. If you’ve been following the FODMAP diet for a long time you could have been starving the good bacteria, by removing their food source (fermentable starches).

Certain types of bacteria help to:

  • protect the lining of the gut,
  • prevent the tight junctions between the cells from becoming ‘leaky’, and
  • ward off pathogens by lowering the pH balance of the gut
  • ‘talk’ to the immune system to reassure it everything is well.

If you don’t have enough of these good bacteria, or some colonies of microbes have grown and overrun the gut, then we can start reacting to foods, or experiencing more bloating and gas. You can either take probiotics, eat fermented foods, or eat high levels of prebiotics (fibre) which feed the microbes.

If you want a bit more information on Prebiotics and IBS I’ve written about that before.

Some probiotics can help to address the balance of microbes in the gut, so might be useful as a supplement to your diet.

So you can see there are lots of other potential reasons for your IBS symptoms, other than FODMAPs.

The final thing to highlight, is that if your issue is bacterial (e.g. dysbiosis, or SIBO), then the FODMAP diet will only remove the triggers, but not resolve the bacterial overgrowth.

So symptoms can come back. If you’ve been going round in circles with your diet get in touch for a personalised nutrition plan.

When the low FODMAP diet doesn't work - Goodness Me Nutrition (2024)

FAQs

What to do when the low FODMAP diet doesn't work? ›

If you're still experiencing no improvement in your symptoms, it might be worth returning to your Gastroenterologist for further investigations, or seeing a Dietitian who can investigate other dietary triggers, such as naturally occurring food chemicals (salicylates, amines and glutamates) that may be responsible for ...

What is bad about low FODMAP diet? ›

The low FODMAP diet can be helpful for symptom management but is not a direct treatment for IBS or SIBO. Long term strict FODMAP restriction can have adverse effects such as a reduction in Bifido and butyrate producing bacteria, and creating anxiety and fear around food.

Why do I feel worse on a low FODMAP diet? ›

You may also be eating more starches and sugars from hyper-processed gluten free, low FODMAP packaged foods than usual, which may overwhelm the absorption capacity of a sensitive, hyper-active gut. If you suspect this, try eating more fruits, vegetables, nuts and seeds and see how you feel.

What is the success rate of the low FODMAP diet? ›

The low-FODMAP diet has a high predicted success rate for people with IBS, but up to 25% may not benefit. For all other conditions, research is more limited, but there's reason to believe it may help with symptom management in cases of SIBO, IBD and functional dyspepsia.

What happens if you stay on the low FODMAP diet too long? ›

If you skip these foods for too long, you may starve helpful bacteria colonies and cultivate unhealthy bacteria. Over time, if you follow only strict low FODMAP eating, you might notice yourself getting more tired, having more headaches, constipation, muscular weakness, or getting sick more easily.

Why am I losing weight on low FODMAP diet? ›

“The low FODMAP diet isn't meant for weight loss, but you can lose weight on it because it eliminates so many foods. For someone at an already too low weight, losing more can be dangerous.”

What food has the highest FODMAP? ›

Some of the highest FODMAP beans and legumes include baked beans, black-eyed peas, broad beans, butter beans, chickpeas, kidney beans, lentils, soybeans, and split peas. Sweeteners are hidden everywhere in the Western diet and they can increase the total FODMAP content of even low-FODMAP foods.

Is Greek yogurt low in FODMAP? ›

Greek yogurt contains less lactose due to its production process making it a great low FODMAP option, as long as you're sticking to a low FODMAP serving size and adding only low FODMAP sugars/fruits/sweeteners (if any).

Is sweet potato low in FODMAP? ›

Sweet potato contains fructose, a type of FODMAP, but in small amounts. It's considered a low FODMAP food, but you should consider keeping your intake to 1/2 cup (75 grams) cooked. Comparatively, yam is lower in FODMAPs. You may be able to eat larger amounts of it on a low FODMAP diet.

What is the most common FODMAP intolerance? ›

On average, each patient showed intolerance to 2.5±2 FODMAPs. The most common FODMPs to trigger symptoms were fructans (56%) and mannitol (54%), followed by GOS, lactose, fructose, sorbitol, and glucose (respectively 35%, 28%, 27%, 23%, and 26%).

What diet is closest to FODMAP? ›

The gluten free diet has some similarities to the FODMAP diet and it is often tried first before undetaking the low FODMAP diet.

Why am I so tired on a low FODMAP diet? ›

Unfortunately, many newbies to the low FODMAP diet remove foods entirely from their diet instead of swapping them. Deleting foods from your diet can reduce the calories (energy) available for your body and your nutrient intake, which can make you feel tired or headachy.

What does it mean if the low FODMAP diet doesn't work? ›

One reason the low-FODMAP diet may not work is that you may not have IBS but actually have another disorder. Your healthcare provider may need to do more tests, or you may need to go to a specialist. Other possible diagnoses include: Inflammatory bowel disease.

What are the negatives of the fodmap diet? ›

Risk of the low-FODMAP diet

For starters, this diet is highly restrictive. While the initial restrictive phase is only temporary, nutritional deficiencies—especially inadequate fiber intake—can occur and may worsen GI symptoms.

How long should you stay on a low FODMAP diet? ›

Read on for a simple guide to the 3 phases of the Monash University Low FODMAP Diet™.
  • Low FODMAP. This is to be commenced under the supervision of a dietitian for a period of 2-6 weeks. ...
  • Reintroduction. This step involves reintroducing foods back into your diet in a methodical way to determine. ...
  • Personalization.
Jan 15, 2018

Why does low FODMAP diet take so long to work? ›

The amount of time it takes for someone to see results from a low FODMAP diet depends on many factors, including how strictly they follow the diet and their individual body composition and metabolism. Most people will start to feel better after about two weeks of following a low FODMAP diet.

How long does it take to see results from a low FODMAP diet? ›

Many people start to feel better as early as two days into the elimination phase, but for some, it can take a few weeks. So don't be discouraged! Keep in mind that you should not have any cheat days on this diet. The better you stick to it, the more effective and accurate the results, so stay strong and low FODMAP on!

How do you fix FODMAP intolerance? ›

If you have been diagnosed with FODMAP intolerance, your doctor or dietitian may recommend a low-FODMAP diet. This is a temporary diet that eliminates all high-FODMAP foods. The purpose of the diet is to allow your digestive system to rest and heal by eating only Low FODMAP foods for 2-4 weeks.

How do you survive low FODMAP? ›

The solution is to deliberately increase your intake of fiber from low-FODMAP foods: eat a wide variety of low FODMAP fruits and vegetables, grains and legumes, and small servings of nuts and seeds. Low FODMAP fibers are fermented more slowly and are less likely to disrupt fluid balance in the gut.

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