Getting Started on the Low FODMAP Diet: Elimination Phase

Figuring out what you can eat, what you can’t eat and then navigating the supermarket can all be overwhelming when starting the low FODMAP diet. This guide will talk you through what the low FODMAP elimination phase or restriction phase is and answer your low FODMAP diet questions to help you get symptom free faster.

Before You Start The Low FODMAP Elimination Phase

Before you start the low FODMAP diet, it is important that you stop and go and see your doctor and if possible a FODMAP trained dietitian.

Your doctor needs to rule out that your troubling GI symptoms are not being caused by other serious medical conditions like coeliac (celiac) disease, inflammatory bowel disease, Crohn’s disease, cancer or other medical conditions (1 2). Once you are on the low FODMAP diet, testing for some of these medical conditions can become more challenging.

The low FODMAP diet is a medical nutritional therapy used as a tool to help people with IBS manage their symptoms and understand food triggers. It’s restrictive and can be socially awkward so the diet isn’t the best option for everyone. It should also only be followed strictly for 2 to 6 weeks and then you can start re-challenging and re-introducing FODMAPs.

If possible, a registered dietitian with specialised knowledge of the low FODMAP diet can you help navigate the complexity of the diet while making sure you are get the nutritional requirements that your body needs (2). Your dietitian will also help you troubleshoot if your symptoms aren’t settling, before walking you through re-challenging and reintroducing high FODMAP food back into your diet.

What are FODMAPs?

If you are sitting there thinking FOD-what? Then you aren’t the only one… No FODMAP isn’t an acronym out of a sci-fi movie, nor is it the latest and greatest new candy flavour. In super simple terms FODMAPs are short chain carbohydrates (sugars). Don’t panic – the diet isn’t actually sugar free and you can still enjoy a low FODMAP treat! These FODMAPs naturally occur in a wide range of fruit, vegetables, cereals, grains, dairy products, legumes and pulses. The FODMAPs are poorly absorbed in our small intestines where they draw water into our bowels. Next the FODMAPs are fermented by our gut bacteria in our large intestines where they create gas, which triggers unpleasant GI symptoms.

Let’s break the FODMAP acronym down:

Fermentable

This is simply the process where our gut bacteria feast on the FODMAPs, breaking down the undigested carbohydrates to produce gas (hydrogen, methane and carbon dioxide) (7 8).

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Oligo-Saccharides

This nasty sounding FODMAP group isn’t as scary when you break it down into it’s sub groups: fructans and galactans. Fructans (fructo-oligosaccharides or FOS) are commonly found in onion, garlic, wheat, rye, barley and dried fruit. Galactans (galacto-oligosaccharides or GOS) are often found in silken tofu, pistachios, cashews, legumes and pulses (7  8).

Have you ever wonder why beans make everyone fart? This is because humans weren’t born with the right enzymes to fully digest oligosaccharides, so they will make everyone gassy but only trigger IBS symptoms in some people (2 8).

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 Di-Saccharides 

The only disaccharide you need to worry about is lactose which can be found in products derived from cow, sheep or goat’s milk. Lactose contains two sugar units that need to be ‘unzipped’ using an enzyme called lactase before our bodies can absorb it. If your gut lacks lactase enzymes then you will struggle to process high lactose products and they are likely to trigger symptoms.

Lactose is found in milk, yoghurt and soft cheese (7 8). The good news is that lactose free milk or yoghurt, hard cheeses and butter are all suitable for the low FODMAP diet.

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Mono-Saccharides

This is simply fructose that is found in excess of glucose. To process fructose effectively our bodies need equal amounts of glucose to stop it being malabsorbed. This means on the low FODMAP diet we only worry about foods containing excess fructose like apples, pears, mango, honey, asparagus, and high fructose corn syrup.

Up to 30% to 40% of healthy individuals and people with IBS will malabsorb excess fructose (2 8).

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And Polyols

Polyols are sugar alcohols but they won’t make you drunk. They are found in a wide range of fruit (apples, pears, stone fruit, lychee) and vegetables (mushrooms, cauliflower, sweet potato). They are also man-made and used in products as low calories artificial sweeteners like protein powders, chewing gum, and diabetic candy.

Polyols are only partially absorbed in our small intestines, the remaining polyols continue to our large intestine where they are fermented by our gut bacteria, causing issues for some people (2  8).

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What is the Elimination Phase?

The low FODMAP diet is broken down into three phases: elimination (or low FODMAP phase), re-challenge and reintroduction, and then adapted FODMAP diet. The elimination or restriction phase is the initial phase of the low FODMAP diet where the goal is to significantly reduce your IBS symptoms through lowering the amount of FODMAPs you eat (5). To achieve this we need you to remove all high FODMAP foods from your diet and focus on eating low FODMAP foods and serving sizes instead.

It is recommended that you only stay in the restrictive phase for a 2 to 6 week period while you gain symptom control (6 7 8).  Once your symptoms are under control you can then start the reintroduction phase with the guidance of your dietitian. It’s important that you reintroduce some high FODMAP foods back into your diet as they are important for long term gut health.

Where do you find low FODMAP food lists & serving size information?

If you are working with a dietitan then they will normally provide you with a list of high and low FODMAP foods. Otherwise the Monash University FODMAP App or FODMAP Friendly App are great resources and have up-to-date lists of high and low FODMAP Foods.

The Monash app clearly indicates high and low FODMAP foods through a traffic light system, and gives safe serving sizes for each food (2). Their system works by rating foods as green (low FODMAP dose), orange (moderate FODMAP dose), and red (high FODMAP dose) (5). Monash University also produces a printed guide, The Monash University Low FODMAP Diet booklet.

The FODMAP Friendly app has a pass/fail system for each food which shows their FODMAP rating. You can also look at the FODMAP percentages for each food to see if the FODMAPs compound when you eat different foods together.

When undertaking the elimination phase, Monash University researchers recommend that you avoid the red foods/portion sizes, limit the orange foods/portion sizes, and eat mainly the green rated foods/portion sizes (5).  You can eat a number of green rated (low FODMAP) foods per meal, however it is important that check the suggested serving sizes, as some foods become high FODMAP in larger serves (5). You will find more information on the importance of serving sizes here.

Where do sneaky FODMAPs hide?

FODMAPs love to hide in processed products and many pre-made products and sauces contain high FODMAP ingredients. Look out for high FODMAP fruits/vegetables (particularly onions and garlic), high fructose corn syrup (HFCS), inulin, honey, and wheat (2 3). During the elimination phase it is recommended that you avoid high FODMAP ingredients if possible. When it comes to wheat, rye, and barley try to avoid products that list these ingredients as first to third in the ingredient list (3). For more information on how to read labels please read our Low FODMAP Guide To Reading Labels.

Is gluten a problem while on the low FODMAP diet?

There is often a lot of confusion around this point. Gluten is a protein and FODMAPs are carbohydrates. This means gluten does not need to be avoided, however gluten free products are often recommended while on the diet. This is because wheat, rye and barley which contain gluten also contain oligosaccharides so eating gluten free helps you avoid these FODMAP sources. The goal is to limit the oligosaccharides and not the gluten (7). Small amounts of wheat can be low FODMAP and should not be a problem unless you also have coeliac disease. Not all gluten free products are FODMAP friendly as they can contain sneaky FODMAPs.

Are alcohol & caffeine allowed during the elimination phase?

While on the low FODMAP elimination phase it is often recommended that you limit your consumption of alcohol and caffeine  (1 2). While small amounts of caffeine and most alcohols are not high in FODMAPs, they can be gut irritants and can make IBS symptoms worse (1 2). This means you should test alcohol and caffeine in the reintroduction phase of the low FODMAP diet after talking to your dietitian.

How do you deal with constipation on the low FODMAP diet?

The low FODMAP diet is lower in fibre which can be problematic for some people and cause constipation. This means you may need to increase low FODMAP fibre rich foods and your water intake (2). If you are struggling with constipation after starting the low FODMAP diet make sure you consult with your dietitian.

When do you reintroduce high FODMAP foods?

Once your symptoms are settled you can start re-challenging and re-introducing high FODMAP foods back into your diet after a 2 to 6 week period (6 7). Read our guide to reintroducing FODMAPs for more information.

Are A Little Bit Yummy’s recipes safe for the elimination phase?

A Little Bit Yummy’s recipes are based on the Monash Low FODMAP App serving size guidelines and have been checked by low FODMAP trained registered dietitian. This means the recipes are safe to use as a resource during the elimination phase.

If you have questions please feel free to contact me on Facebook or by email at [email protected]

More Tools to Help

We know that taming your gut symptoms can be challenging but we’re here to help! We can support you through your journey from starting the low FODMAP diet to reintroducing FODMAPs and finding your food freedom in our Wellness Club.

Explore our 600+ delicious low FODMAP recipes, plan your meals with our weekly meal plans, track your symptoms, and get extensive help for all the stages of the low FODMAP diet through our e-courses. All our resources are dietitian reviewed. So what are you waiting for? Come and join us in the Wellness Club!