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What are FODMAPS and the low-FODMAP diet plan?

Rob Hobson
Article written by Rob Hobson

Date published 26 March 2024

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FODMAPs are found in various foods and may be responsible for your digestive discomfort. Registered Nutritionist Rob Hobson explains where FODMAPs can be found and whether avoiding them will help your digestion.

🕒 7 min read

There are many kinds of digestive discomfort, and irritable bowel syndrome (IBS) is particularly common. Symptoms include bloating, wind, diarrhoea, constipation, and tiredness. Dietary factors such as caffeine, alcohol, or spicy or fatty foods can trigger symptoms, alongside stress and erratic eating patterns. Certain types of carbohydrate also play a role, and this is where the low-FODMAP diet comes in.

What are FODMAPs?

FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols.

  • Fermentable: foods that do not fully digest/absorb in the intestine, so ferment in the large bowel.
  • Oligosaccharides: Two groups of oligosaccharides cause symptoms: Fructans and galacto-oligosaccharides. Everybody absorbs these poorly, as we cannot digest them in the small intestine.
    • Fructans are also known as fructooligosaccharides (FOS) and are chains of sugar fructose of different lengths. These are found in wheat products (bread/breakfast cereal/pasta), some vegetables (e.g. onion, garlic, artichoke) and as an ingredient added to some processed foods as a prebiotic (e.g. FOS, oligofructose or inulin.)
    • Galacto-oligosaccharides (GOS) are chains of the sugar galactose. The primary dietary sources are pulses, beans, legumes and cashew or pistachio nuts.
  • Disaccharides: Lactose is a sugar found in all animal milk. Milk and yoghurt are the primary sources of lactose monosaccharides: fructose is a simple sugar but, in excessive amounts, may be poorly absorbed by some.
  • Polyols: Polyols are sugar alcohols such as sorbitol, mannitol, and xylitol. These are poorly absorbed by most people. They occur naturally in some fruits and vegetables but are also used as artificial sweeteners in sugar-free chewing gum, mints, and other low-calorie or sugar-free products.

These compounds are poorly absorbed in the small intestine, so they move through to the large intestine undigested, fermented by gut bacteria. This process produces gases, which lead to the symptoms associated with IBS.

What is the low-FODMAP diet?

The low-FODMAP Diet is a dietary strategy developed by researchers at Monash University in Australia. This diet aims to control your diet for the foods that fall into the FODMAP categories, to help alleviate symptoms in those with IBS or other functional gastrointestinal disorders. The diet has three distinct phases: elimination, reintroduction, and personalisation.

Elimination Phase

During this phase high-FODMAP foods are temporarily eliminated. This phase lasts from two to six weeks. The reduction in FODMAP intake helps calm gut symptoms and relieves discomfort.

Reintroduction Phase

After the elimination phase, individual FODMAPs are gradually reintroduced one at a time. This step is needed to help identify specific FODMAPs that trigger symptoms. It's important to understand that not everyone will react to all FODMAPs or in identical amounts.

Personalisation Phase

Once FODMAPs have been identified from the reintroduction phase, individuals can develop a personalised long-term eating plan. This plan will minimise the consumption of high-FODMAP foods that trigger symptoms, while still maintaining a varied and nutritious diet.

What foods can you eat freely when following a low-FODMAP diet?
  • Meat, poultry, fish, eggs, or vegetarian protein foods. Eat 1-2 portions per day (one portion is 75g-100g, or 2 eggs.)
  • Fresh and frozen meat without sauce or coating: beef, chicken, duck, lamb, pork (including bacon and ham), turkey.
  • Fresh or frozen shellfish, white fish, oily fish.
  • Tinned fish in brine or oil.
  • Eggs (boiled, fried, poached, scrambled.)
  • Firm tofu, tempeh.
  • Quorn (check ingredients: some varieties contain onion and/or garlic.)
  • Textured vegetable protein (soya mince.)

Fats, oils & spreads

Fats are high in calories, so they should be used sparingly in a healthy diet. Excess fats can contribute to IBS symptoms in some people. Choose polyunsaturated or monounsaturated where possible.

  • Cooking oils, margarine, low-fat spreads, butter, ghee, lard, and suet.

Is the low-FODMAP diet right for everyone?

The low-FODMAP diet has shown promising results for many people, but not everyone. Some people may not experience significant symptom improvement; others may only need to avoid specific high-FODMAP foods or certain amounts.

This diet is not easy to do alone, so it's advisable to find a dietitian or registered nutritionist trained to guide you through its different phases. Correctly qualified health professionals can also help diagnose digestive issues accurately.

It's also worth noting that this is not meant to be a long-term diet. The goal is to identify specific trigger foods and to create a sustainable, individualised diet that minimises the occurrence of symptoms.

Is there any science to support the diet?

A significant body of research demonstrates the effectiveness of the low-FODMAP diet and its ability to help reduce symptoms such as bloating, gas, and abdominal discomfort. A 2017 study in the Journal of Gastroenterology and Hepatology found that individuals with IBS who followed a low-FODMAP diet experienced significant improvements in symptom severity and quality of life compared to those who did not.

Navigating the Low-FODMAP Diet

Embracing the low-FODMAP diet requires dedication, patience and an open mind. Here are some critical considerations for those considering this dietary approach.

Learn about FODMAPs beforehand

Familiarise yourself with FODMAP-containing foods and their appropriate portion sizes. Remember that portion size matters, as you may tolerate small amounts of high-FODMAP foods.

Balance your nutrition

While following the low-FODMAP diet, it's crucial to maintain a balanced intake of essential nutrients. Be sure to include a variety of well-tolerated nutrient-rich foods. Given the restrictive nature of the diet, taking a multivitamin and mineral supplement may be helpful to avoid nutrient insufficiency. 

Everyone is different

Everyone will respond to FODMAPs in their own way. Certain individuals might react to specific FODMAPs while tolerating others without issue. The reintroduction phase helps to uncover these individual triggers.

Keep track of your symptoms

Keep a food and symptom diary to track how different foods impact your digestive health. This can help you make informed decisions during the reintroduction phase.

What does a low-FODMAP meal plan look like?

Even though it can be restrictive, there are many ways to prepare meals to suit your diet. These meals may vary depending on your trigger foods.


  • Porridge or wheat-free cereal and a suitable type of milk.
  • Wheat and rye-free toast with cheese, suitable jam and peanut butter.
  • 2 eggs on wheat and rye-free or 100% sourdough spelt toast.
  • Cheese and chive omelette.
  • Smoothie made with suitable fruit and lactose-free yogurt.
  • Cooked breakfast – bacon, egg, tomato, hash brown with wheat and rye-free or sourdough spelt toast.


  • Wheat and rye-free sandwich or wrap, or wheat and rye-free crispbread with lean meat, canned fish, or cheese.
  • Homemade soup made with suitable vegetables and wheat-free bread.
  • Baked potato or rice with tuna, cheese or homemade chilli.
  • Salad, rice salad, potato salad, gluten-free pasta salad with cold meat, canned tuna, boiled eggs or cheese.
  • Sushi or sashimi.


  • Lean meat, poultry, fish, Quorn or tofu with suitable vegetables and rice, rice noodles, wheat-free or gluten-free pasta, potatoes or polenta.
  • Risotto or omelette with salad.
  • Gluten-free pasta with Bolognese or chilli (no onion or garlic) and salad.
  • Corn taco shells with turkey mince, crème fraiche and salad.
  • Suitable fruit salad, rice pudding, ice cream or custard.


  • Suitable fruit.
  • Low-fat yoghurt (check ingredients + lactose-free if needed.)
  • Vegetable sticks and dip (check it doesn't contain onions.)
  • Cheese and tomato or peanut butter on rice crackers or oat cakes.
  • Handful of suitable nuts.
  • Wheat-free and gluten-free cakes.

The low-FODMAP diet is an evidence-based approach to help identify the trigger foods that can lead to uncomfortable symptoms associated with gut disorders such as IBS. Please be aware that the diet should be done alongside a suitably trained dietitian or registered nutritionist, and does not always result in an alleviation of symptoms.

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Rob Hobson

About Rob Hobson

Rob Hobson MSc RNutr is an award-winning registered nutritionist (AFN) and sports nutritionist (SENR) with over 15 years of experience. He founded London-based consultancy RH Nutrition, and has degrees in nutrition, public health nutrition and sports nutrition.