Do you ever feel like your stomach is staging a rebellion against you? The discomfort, the bloating, the constant battle with unpredictable symptoms-living with Irritable Bowel Syndrome (IBS), excessive gas, or bloating can be downright exhausting. Are you still getting bloated on a low FODMAP diet even though you’re following it perfectly? Many people have this exact same frustrating experience. Here’s the thing - clinical research shows the low FODMAP diet actually works for up to 86% of people with IBS (1). This article provides a detailed guide to understanding why bloating might persist on a low-FODMAP diet and how to address it.
Understanding the Low FODMAP Diet
FODMAPs, which stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, are a group of carbohydrates found in various foods. FODMAP is an acronym used to describe a group of carbohydrates that can be poorly absorbed in the small intestine and rapidly fermented by bacteria to produce gas. This can lead to bloating, excess gas, pain and nausea. Some individuals are more sensitive to these foods than others. The Low FODMAP Diet works by reducing the intake of these fermentable carbohydrates, thereby alleviating symptoms and providing much-needed relief. But why is the Low FODMAP Diet particularly beneficial for those with IBS, excessive gas, and bloating? It all comes down to the way FODMAPs interact with the gut. For some people, these carbohydrates are poorly absorbed in the small intestine and instead ferment in the colon, leading to the production of gas and other uncomfortable symptoms.
The Low FODMAP Diet works by reducing the intake of fermentable carbohydrates, thereby alleviating symptoms and providing much-needed relief. The diet should be relaxed long term to ease the burden of following the diet, but more importantly to reintroduce some FODMAPs back into the diet for their potential benefits. This benefit arises from the fermentation of FODMAPs by gut bacteria - the reason we restrict FODMAPs in the first place - but small amounts of FODMAPs are fuel for good bacteria and is likely to be important in long term gut health.
Common FODMAPs and Their Sources
FODMAP stands for fermentable oligo-, di-, monosaccharides and polyols (1). These short-chain carbs are resistant to digestion. Instead of being absorbed into your bloodstream, they reach the far end of your intestine, where most of your gut bacteria reside. Your gut bacteria then use these carbs for fuel, producing hydrogen gas and causing digestive symptoms in sensitive individuals. FODMAPs also draw liquid into your intestine, which may cause diarrhea.
Common FODMAPs include:
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- Fructose: a simple sugar found in many fruits and vegetables that also makes up the structure of table sugar and most added sugars
- Lactose: a carbohydrate found in dairy products like milk
- Fructans: found in many foods, including grains like wheat, spelt, rye and barley
- Galactans: found in large amounts in legumes
- Polyols: sugar alcohols like xylitol, sorbitol, maltitol, and mannitol. They are found in some fruits and vegetables and often used as sweeteners
Why Bloating Persists: Hidden FODMAPs and Stacking
Even when diligently following a low-FODMAP diet, bloating can persist due to several factors. Two common issues are hidden FODMAPs in processed foods and the "stacking effect," where small amounts of multiple FODMAPs accumulate to trigger symptoms.
The Hidden Ingredient Trap
The first issue is what we call the hidden ingredient trap, and it catches almost everyone off guard. Food manufacturers use garlic powder and onion powder in almost everything. Even small amounts can trigger symptoms since garlic is high in fructans, one of the key FODMAP groups. Common culprits include seasoning blends, stock or bouillon cubes, seasoning packets, marinades, sauces, and even seemingly innocent items like rice crackers. The name literally says “chicken,” and many people assume it’s safe because chicken doesn’t contain FODMAPs and neither does salt.
To protect yourself from this trap, you need to develop systematic ingredient-checking habits. Be particularly suspicious of anything labeled “natural flavoring” or “spice blend” without listing specific spices, as these can contain garlic and onion compounds.
The Stacking Effect: Cumulative FODMAP Load
Your FODMAP tolerance works like a coffee cup - each person’s capacity is different. If you add liquid slowly, drop by drop, even a small cup stays manageable. But pour in too much too quickly, and even a large mug will overflow. Individually, each portion fit within low FODMAP guidelines. This stacking effect can occur throughout the day as well. You might have low FODMAP oats and strawberries for breakfast, snack on almonds, then eat avocado and tomatoes at lunch. Your gut needs time to clear FODMAPs from one meal before processing the next load. Additionally, everyone’s tolerance varies significantly.
To prevent stacking, use the Monash app more strategically than simply checking green versus red classifications. Examine the actual FODMAP types present in each food. Similarly, if you’re having rolled oats, be cautious about adding other oligosaccharide-containing foods to the same meal. Track symptoms across entire days, not just individual foods. This broader perspective allows you to identify patterns and connections that single-meal analysis might miss.
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Beyond FODMAPs: Other Potential Causes of Bloating
While clinical research shows the low FODMAP diet works for up to 86% of people with IBS, this leaves 14% for whom low FODMAP is not the complete solution. Additionally, sometimes the real issue involves factors like chronic stress and anxiety, often referred to as the gut-brain connection, or a highly sensitive vagus nerve. The symptoms of SIBO are very similar to many other digestive issues, including IBS, Crone’s, and colitis.
SIBO and Bloating
SIBO can definitely be one cause of that uncomfortable, even painful bloated feeling. Many people with SIBO experience bloating and gas, especially after eating. As the intestine stalls, bacteria can overtake the intestinal tract and cause damage. For sufferers of SIBO, the bacteria are out of balance. If your doctor suspects SIBO, they can run a simple QuinTron breath test.
For those who suffer from SIBO, dietitians theorize a FODMAP diet “starves” the bacteria that is overgrowing within your gut. As a result, it can lower the number of bacteria and help restore balance to your digestive tract.
Gut-Brain Connection
Stress can also be a major contributor (4, 5). Understanding these limitations helps explain why some people continue experiencing symptoms despite perfect dietary compliance. Our intestinal organs are very clever and have ‘stretch sensors’ in their muscular wall that are able to sense when the organ is distended. People with IBS tend to have particularly sensitive stretch sensors. When the gut stretches from increased pressure, the nerves in our gut tend to overreact. When the nerves in our gut overreact to being stretched, our level of discomfort increases.
Implementing the Low FODMAP Diet Effectively
Implementing the Low FODMAP Diet may seem daunting at first, but with the right guidance and resources, it becomes much more manageable.
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- Registered Dietitians: Consulting with a registered dietitian who specializes in gastrointestinal health can provide personalized guidance and support throughout your Low FODMAP journey.
- Online Communities: Joining online communities and forums dedicated to the Low FODMAP Diet can connect you with others who are on a similar path.
Three Phases of the Low-FODMAP Diet
The diet has three phases: an elimination phase, a reintroduction phase and a maintenance phase that’s customized to you.
- Elimination Phase: During the elimination phase, you'll avoid all of the high-FODMAP foods - a list of specific fruits, vegetables, dairy products and grains. The low-FODMAP diet reduces these carbohydrates in a person’s diet to temporarily control their symptoms, but it is not meant to be followed long-term.
- Reintroduction Phase: After two to four weeks, you’ll begin the reintroduction phase, in which you systematically add foods back in. After three weeks, you can reintroduce some of these foods - one at a time. This allows you to determine which food causes your symptoms. If you find that a certain type of food strongly upsets your digestion, you may want to permanently avoid it (8).
- Maintenance Phase: The third phase keeps what works for you and leaves out what doesn’t.
Reintroducing FODMAPs and Interpreting Symptoms
Many people try the reintroduction or rechallenge phase and state they have failed - their symptoms returned on reintroduction of the foods and they went back to a strict low FODMAP diet. This will be necessary for symptom control only in the minority of extremely sensitive individuals. For everyone else, it may be that smaller amounts of FODMAPs need to be trialed, and in fact, the return of symptoms needs to be looked at in a different way.
When you experience symptoms, it is vital that you are tuned in to the severity. Pain and significant discomfort are not OK and you can discuss these outcomes with your treating dietitian who can advise further on future challenges and food trials you may better tolerate. But for many people, the reintroduction of FODMAPs, or FODMAP ingestion when eating, results in gas production and a little bloating. The initial thought is that there has been a reaction and the food should again be removed from the diet, but we ask you to think about it in a different light.
Fermentation and gas production after eating high FODMAP foods is beneficial to the gut. If you experience some gas related symptoms that are tolerable and perhaps just include some mild bloating and flatus, this could be a good sign that you are providing fuel that encourages good bacteria in your gut.
Low-FODMAP Food Choices
There is a wide variety of healthy and nutritious foods that you can eat on a low FODMAP diet.
- Meats, fish, and eggs: These are well tolerated unless they have added high FODMAP ingredients, like wheat or high fructose corn syrup.
- Nuts and seeds: Nuts and seeds that you can eat include peanuts, macadamia nuts, pine nuts, and sesame seeds but not pistachios, almonds, or cashews, which are high in FODMAPs.
- Fruits: Unripe bananas, Cantaloupe, Grapefruit, Kiwi, Lemons, Lime, Mandarins, Melons (except watermelon), Oranges, Passionfruit, Strawberries
- Vegetables: Alfalfa, Bell peppers, Bok choy, Carrots, Celery, Chives, Cucumbers, Eggplant, Ginger, Green beans, Kale, Lettuce, Olive, Parsnips, Potatoes, Radishes, Spinach, Spring onions (only green), Squash, Sweet potatoes, Tomatoes, Turnips, Water chestnuts, Yams, Zucchini
- Grains: Corn, Oats, Quinoa, Rice, Sorghum, Tapioca
- Other foods or ingredients: All fats and oils, Most herbs and spices, Sweeteners (maple syrup and stevia), Dairy products if they are lactose-free as well as hard cheeses and aged softer varieties (like Brie and Camembert), Beverages (water, coffee, green, black, or white tea, etc)
Key Strategies for Managing Bloating
Several strategies can help manage bloating while on a low-FODMAP diet:
- Read Labels Carefully: Be vigilant about checking ingredient labels for hidden sources of FODMAPs like garlic and onion powder.
- Space Out FODMAP Intake: Avoid stacking FODMAPs by spacing out meals and snacks, allowing your gut time to process them.
- Monitor Portion Sizes: Be mindful of portion sizes, as even low-FODMAP foods can trigger symptoms if consumed in excess.
- Consider Other Factors: Address potential contributing factors like stress, anxiety, and underlying conditions like SIBO.
Importance of Professional Guidance
To ensure success, it is highly recommended that you seek guidance from a Registered Dietitian who is experienced with the low-FODMAP diet. A FODMAP-trained Dietitian is a great person to have on your IBS management team. A Dietitian can perform a full patient assessment, including a symptom assessment and diet history. They will be able to answer all of your FODMAP questions, and help you choose the best course of action when it comes to the way in which you’d like to implement the diet. Also, there is greater risk of nutritional inadequacy when eating low FODMAP which could lead to nutritional deficiencies in the long term. When you try to embark on the low FODMAP diet yourself, it can be very easy to make mistakes and feel discouraged.