Sarah Glinski, RD
Understanding the Low FODMAP Diet
The low FODMAP diet is an elimination diet that's often used in the management of digestive conditions like irritable bowel syndrome (IBS). It involves temporarily reducing your intake of high FODMAP foods with the ultimate goal of improving symptom control and determining which (if any) FODMAPs trigger symptoms.
Undertaking a low FODMAP diet is not to be taken lightly, as it involves restricting many foods that are normally part of a balanced diet. Understanding what life will look like before and after low FODMAP diet implementation is key to ensuring you start your low FODMAP journey on the right foot.
The low FODMAP diet has three phases: Elimination, reintroduction, and personalization. Unfortunately, many people get stuck in the elimination phase and don't move on to the reintroduction and personalization phases. This can lead to following a highly restrictive diet long-term, which can negatively impact both physical and mental health, as well as reduce the amount of good bacteria in your gut.
What Are FODMAPs?
FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. It refers to the fermentable, short-chain carbohydrates that get fermented by your gut bacteria because they're poorly absorbed in the small intestine and instead enter the large intestine intact. These food triggers can lead to digestive distress, such as gas, bloating, and changes in bowel movements in people with a FODMAP intolerance.
Many foods contain FODMAPs, including fruits, vegetables, whole grains, nuts, legumes, and dairy products. There are five FODMAP categories. They are:
You can use the Monash University FODMAP app to see which foods contain different FODMAPs.
Purpose of the Low FODMAP Diet
While you may have heard that the purpose of the low FODMAP diet is to completely eliminate FODMAPs, that's not exactly true. Instead, the low FODMAP diet is about temporarily reducing your intake of high FODMAP foods so you can identify which FODMAP categories you're sensitive to, your individual food triggers, and what portion sizes work for your body. Rarely is a person sensitive to all FODMAPs, so the low FODMAP diet is a way to eventually expand your diet while still managing IBS symptoms.
The Elimination Phase: Before Reintroduction
The first phase of the low FODMAP diet is the elimination phase. Before you start the elimination phase, you may be feeling frustrated by gastrointestinal symptoms like gas, bloating, abdominal pain, diarrhea, and constipation. Fortunately, many people get significant relief from their symptoms within a few weeks of starting the elimination phase.
During the elimination phase, you'll limit your intake of high FODMAP foods for two to six weeks and focus on including lower FODMAP foods to ensure a balanced diet. However, if you don't notice a reduction in symptoms by the two-week mark, you may be a low FODMAP diet non-responder (research suggests that only 50% to 80% of people with IBS find relief with a low FODMAP diet). If this is the case, it's best to go back to your normal diet and try other IBS management strategies.
Common Challenges Faced in the Elimination Phase
While the elimination phase of the low FODMAP diet can bring significant symptom relief, it's not without its challenges. Here are four common challenges people experience during this phase:
- Not getting enough fiber: Many high fiber foods, like beans, certain fruits and vegetables, and certain whole grains, are limited during the elimination phase of the low FODMAP diet. This can lead to constipation if other high fiber foods are not incorporated. Low FODMAP foods that are high in fiber include chia seeds, ground flax, psyllium husk, canned chickpeas (up to ¼ of a cup), canned lentils (up to ¼ of a cup), quinoa, millet, raspberries, blueberries, carrots, parsnips, and potatoes (leave the skin on for even more fiber). Try to incorporate these foods to ensure you're getting enough fiber.
- Limited food variety: Because it's an elimination diet, the low FODMAP diet can feel restrictive when you're still learning which foods to include, making it hard to plan meals or feel satisfied.
- Nutrient gaps: Cutting out many commonly eaten foods may reduce intake of important nutrients like calcium, B vitamins, and vitamin D.
- Social and emotional stress: Navigating eating at restaurants, date nights, or travel can feel overwhelming and isolating during this phase. To make things easier, try planning ahead by calling restaurants before you go to see if they offer low FODMAP options, or bring your own snacks while traveling.
Despite the challenges of the low FODMAP diet's elimination phase, many people can follow it successfully. Working with a healthcare provider like a registered dietitian who can support you and provide personalized meal and snack recommendations can eliminate some of the stress associated with the diet.
The Reintroduction Phase: Transitioning Back to FODMAPs
Once you've been following the elimination phase of the low FODMAP diet for two to six weeks, it's time to start the second phase: FODMAP reintroduction.
Importance of Reintroducing FODMAPs
Many people skip FODMAP reintroduction because they're afraid that reintroducing FODMAPs will trigger their symptoms. But the reintroduction phase of the diet is one of the most important parts of the diet because it enables you to determine exactly which FODMAP groups you're sensitive to. This is key to long-term symptom management because most people are not intolerant to all FODMAP categories. By reintroducing FODMAPs systematically, you'll learn which FODMAP groups and what portion sizes you can tolerate, which can help you expand your diet and ensure you're not permanently restricting health-promoting foods.
A Guide to Reintroducing FODMAPs
When reintroducing FODMAPs, it's important that each FODMAP group is reintroduced separately so you know which foods have triggered symptoms. In general, you'll introduce a group two or three times, with increasingly larger portion sizes. If you're able to tolerate the largest portion size, you can likely tolerate that FODMAP group. If you can only tolerate the food in smaller portion sizes, you may still be able to include it in your meals, albeit in smaller amounts.
Here are some foods you can use to reintroduce each FODMAP category.
Potential Pitfalls of Reintroduction and How to Avoid Them
Here are some of the potential pitfalls of the reintroduction phase of the low FODMAP diet and how to avoid them:
- Reintroducing foods too quickly or too many at once: It's important to take your time with reintroduction! Space out the challenge of different FODMAP groups by at least three days to accurately monitor symptoms.
- Starting with too large a portion size: Begin with small amounts (as listed on "Day 1") and gradually increase if you don't develop symptoms.
- Not keeping a food and symptom journal: There's a likelihood that you'll develop IBS symptoms to some of the FODMAP categories you reintroduce. Track what you eat, including portion sizes, and note down daily symptoms to identify patterns.
- Not ensuring your background diet remains low FODMAP: If you've identified that you can tolerate a certain FODMAP group (for example, GOS), it's important not to add them back to your diet until you've completed the challenges for the other FODMAPs. This is because FODMAP stacking can trigger symptoms like gas and bloating, even if you're eating foods you generally tolerate.
- Giving up too soon if symptoms return: A reaction doesn't mean a complete intolerance. IBS symptoms can also be influenced by factors like stress and poor sleep. If you develop symptoms, go back to the elimination phase for two to three days, then try reintroducing a smaller portion to see if you can tolerate it.
Remember, the reintroduction phase can take anywhere from six to twelve weeks (depending on whether you needed to take breaks due to symptoms developing). It's important to be patient and trust the process!
Long-Term Maintenance Phase After Reintroduction
The third phase of the low FODMAP diet is the long-term maintenance phase and personalized FODMAP diet. This phase focuses on enjoying a flexible approach with lots of dietary variety. Everyone has different FODMAP tolerance, and it can change over time, so it's essential to re-challenge high FODMAP foods every three to six months to help ensure you're not unnecessarily avoiding foods.
During the maintenance phase, try to keep your diet as varied as possible by incorporating a wide range of foods in portions you can tolerate, including fruits, vegetables, grains, legumes, dairy, nuts, and seeds. This will support your gut microbiome and prevent nutritional gaps. Explore new recipes to keep things interesting and avoid falling into a restrictive eating pattern.
While constant monitoring and food journaling aren't typically required, keeping an eye on symptoms, especially during times of stress or while you're traveling, can be helpful. You may also find it beneficial to periodically check in with a dietitian who can help you troubleshoot, reassess tolerances, and ensure your diet continues to meet your health needs over time.
Take Control of Your Diet with FODZYME®
Digestive enzymes like FODZYME help break down FODMAPs before they reach your gut. This science-backed supplement targets specific FODMAPs like the fructans in garlic and onions, enabling you to enjoy a wider variety of foods with less discomfort. Whether you're reintroducing high FODMAP foods or maintaining long-term symptom relief, FODZYME offers a convenient way to support your digestive health. Try it now.
