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.

Everyone’s symptoms are different, so there is no IBS diet that works for everyone

FODMAP doesn’t work for everyone

The low FODMAP diet excludes excessive amounts of fermentable carbohydrates. These are in healthy common foods like apples, avocado, mushrooms or peaches.

Evidence in favour of the FODMAP diet for IBS estimates around 50% to 86% of patients will feel better, averaging around 75% of people.

But what if you’re in the remaining 25%?


What to do if your FODMAP diet isn’t working

If you’re following a low FODMAP diet but still don’t see improvement in your symptoms:

  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
  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.

Reasons the FODMAP diet might not work for you

1. FODMAPs aren’t the cause of your IBS

Before getting your IBS diagnosis hopefully your doctor has ruled out inflammatory bowel disease, coeliac disease and bowel cancer, among other conditions.

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

So what else could it be?

There are other compounds in foods which can cause a sensitive digestion to be triggered, such as 

  • histamine (in aged foods like preserved meats, leftovers, fermented foods)
  • salicylates (inlcuding oranges, berries, sweet potato, broccoli, tea, almonds)
  • alcohol
  • dairy
  • gluten
  • soy
  • corn

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

7 Day Low FODMAP Meal Plan

A tasty 7 day meal plan with over 25 healthy meals for easing IBS flares

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 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.

In addition it is worth working to support your vagus nerve through

  • Deep breathing
  • Yoga
  • Cold water swimming
  • Laughing
  • Singing / chanting


3. Transit time is too fast

Food might be rushing through you too quickly, potentially due to a food intolerance (see above). 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.

Some probiotics can help to address the balance of microbes in the gut.  

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. 

Hi I'm Anna Mapson, registered Nutritionist (mBANT, CNHC). I help people with IBS, SIBO, reflux and other gut health issues.

I can help you to:

  • understand your digestion better, so you recognise your triggers
  • eat a well balanced diet, with tasty meals that are simple to prepare
  • develop healthy, sustainable habits for life

“Anna is amazing! I feel totally transformed"

Find more about 1:1 IBS nutrition consultations