Do you often rush to the toilet after eating and blame it on something you just ate? Afterall, it is logical to think that what goes in must come out. However, the last meal you consumed does not necessarily be the cause of your symptoms.

As FODMAP fermentation generally occurs in the large intestines (a.k.a. the colon – which is around 1.5meters long!), it would usually take more than 4 hours for a reaction to occur. In some cases, it may take up to 24 hours to produce symptoms! These delayed symptoms can make it extremely confusing to work out what the triggers would have been.

So, why would the symptoms of IBS happen so soon after a meal?

Top 5 Potential Causes¹

1. Exaggerated Gastro-Colic Reflex

“Make room!” says the brain to the gut after a meal. The gastrointestinal tract then starts moving food further along your intestines to create more room for the meal you have just consumed.

This domino effect is known as the gastro-colic reflex, which may be the cause of you needing the toilet soon after a meal. In fact, the gastro-colic reflex is normal for all of us. However, this reflex is often exaggerated for people with IBS so they tend to experience a stronger sensation and urge to go to the toilet soon after eating.

2. Abnormal Gut Motility
Gut motility = contraction of gastrointestinal tract muscles to move food along your digestive system. IBS is classified as a functional gut disorder, with abnormal gut motility being a hallmark of IBS; it can lead to bloating, tummy cramps, nausea, diarrhoea or constipation.

3. Visceral Hypersensitivity
Research has shown that IBS sufferers experience visceral hypersensitivity. This means that we have an over-exaggerated perception to pain and experience this in a different way to those without IBS.

When FODMAPs are fermented in the large intestines, gas is produced, which then stretches the gut wall and triggers the sensitive nerves. This pain signal is sent to the brain via ‘the gut-brain axis’. People with IBS tend to have a lower threshold to pain; so we tend to experience stronger abdominal cramps.

4. Caffeine or Spicy Food
Caffeine is a gut stimulant and it is known to increase gut transit time. This means that it can increase gut motility and move food through the gut quicker, leading to looser stools. Sources of caffeine include coffee, tea, cola drinks, chocolate and energy drinks. Spicy food can also irritate the gut and lead to diarrhoea.

5. High FODMAP Foods
FODMAPs are a group of carbohydrate sugars that are poorly digested in the gut. The poorly digested sugars increases water content in the intestines and excess gas production, leading to symptoms such as bloating, flatulence, abdominal cramps and diarrhoea.

But wait, there’s hope! There are a few things you can do to help manage your symptoms.

Tips for Managing IBS

1. Aim for Small, Frequent Meals
By eating smaller portions more frequently through the day, it helps with digestion and reducing the gastro-colic reflex.

2. Avoid High Fat Foods
Go easy on the type of food that would cause discomfort and make your gut work extra hard to digest. These include greasy, deep-fried foods that are high in fat.

3. Low FODMAP Diet
The low FODMAP diet is the first line therapy for managing IBS and it is a scientifically proven diet with lots of research behind it. The low FODMAP diet involves 3 phases: 1) Elimination Phase, 2) Challenge Phase, and 3) Personalisation Phase. Read more about the low FODMAP diet here.

4. Limit Spicy Food and Caffeine
Keep to 2 cups of caffeinated drinks per day and choose water as your main drink. Other non-caffeinated drinks that are tummy friendly include peppermint tea or ginger and lemon tea. It is also important to avoid spicy food if this affects you.

5. Take a Chill Pill
While changing your diet is one way to manage the symptoms of IBS, it is also important to maintain mental and emotional wellness. Psychological factors like stress and anxiety can trigger and aggravate IBS symptoms.

There are numerous research demonstrating that a dysregulated gut-brain axis can affect the gut microbiome and lead to disorders of the gut.

Make it a priority to take some time out to rest, meditate and exercise regularly. Aim for a minimum of 7 hours of sleep every night.

6. Keep a Detailed Food & Symptom Diary
Keeping track of what you have eaten over the last 48-78 hours can give you an insight into what factors may have triggered the flare up.

7. Work with a Specialist Dietitian
We are blessed to be living in a day and age where there are HEAPS of information and support services available. But too much information can sometimes lead to overwhelm and create confusion.

Rather than stressing about what to eat and worrying about when your symptoms are going to flare up next, speak to a specialist Dietitian who specialises in IBS management.


We would love to help you find long-term relief from IBS!

Specialist Dietitian Consultancy is a premium nutrition clinic with clinic locations in Ardross, Cottesloe, Mount Lawley and Mount Pleasant. We also offer Skype or telephone consults for interstate and overseas clients. This blog post is written by Charlyn Ooi (Accredited Practising Dietitian and Credentialled Diabetes Educator). All content written is based on my clinical experience, backed by scientific research and not sponsored in any way. The information provided is general advice and it is important that you see your medical practitioner before undertaking any dietary changes. For further information or to book an appointment, please click on the Contact page.