What Is the Low FODMAP Diet? A Beginner’s Guide

Low-FODMAP diet

Most of us experience digestive disruption from time to time. You might feel bloated or gassy; experience occasional diarrhea or constipation; or struggle with heartburn, abdominal discomfort, or worse. It should come as no surprise that there’s a well-recognized link between digestive disorders and food intolerances. And “FODMAPs,” which are specific poorly digested carbohydrates found in certain foods (including many foods typically considered “healthy”), are often believed to be the culprits. What are FODMAPs, how do they affect the digestive system, and is the low-FODMAP diet right for you? These are all great questions we’ll be diving into today.

What are FODMAPs?

The word “FODMAP” is an acronym for the different categories of these poorly absorbed carbohydrates (according to the length of their chains): “fermentable oligo-, di-, monosaccharides and polyols.” To help break that down (no pun intended):

Fermentable: broken down by bacteria through fermentation

Oligosaccharides: oligo means few and saccharide means sugars. Fructo-oligosaccharides (fructans), which are wheat, rye, onions, garlic, leeks, and inulin, and galacto-oligosaccharides (GOS), which are found in legumes, are examples of oligosaccharides.

Disaccharides: di means two and again saccharides for sugars. The most common example is lactose, which can be found in milk, yogurt, and soft cheese.

Monosaccharides: mono means single and sugars again. Fructose is the most common example, and it can be found in a variety of fruits as well as in honey and agave syrup.


Polyols: these are sugar alcohols. The most common examples are sorbitol and mannitol, which are found in certain fruits (e.g., blackberries, apples, pears) and vegetables (e.g., cauliflower, mushrooms) as well as low-calorie sweeteners, sugar-free gum, many sugar-free foods, and even many health foods (e.g., protein bars).

So, what happens when someone consumes foods containing these FODMAPs? Well, because they can be poorly digested/absorbed in the small intestine, they travel on to the large intestine where they can begin to interact with unhealthy bacteria, which ferment (or, “feed”) on them. They can also have an osmotic effect, which simply means that they can suck up water, which can cause diarrhea. Meanwhile the fermentation leads to the production of gas, which can be especially problematic for “hypersensitive” folks, who may experience stomach pain or cramps, reflux, distention of the lower belly or bloating, constipation, excessive gas, bowel urgency, or diarrhea at least once a week. Not exactly fun.

So, when people talk about eating a “low FODMAP diet,” they’re actually trying to avoid or strictly limit FODMAP-containing foods, and therefore, the uncomfortable, and at times, embarrassing consequences they may experience when eating these types of foods.

A Deeper Dive into the FODMAP Diet

The diet was originally developed by Sue Shepherd, PhD and Dr. Peter Gibson, from the Department of Medicine at Monash University in Australia, for people who were suffering from the symptoms of irritable bowel syndrome (IBS). Evidence from randomized controlled trials suggests that about 70% of IBS patients respond favorably to a low-FODMAP diet. In fact, there are more than 30 studies demonstrating its effectiveness for the estimated 10% of the general U.S. population with symptoms of IBS. But they aren’t the only ones who may benefit.

Based on the beneficial results of the low-FODMAP diet in managing food intolerances and improving digestive-related complaints, it has been recommended for a number of other issues including:

  • Other types of gastrointestinal disorders (e.g., IBD, Crohn’s)
  • Small intestinal bacterial overgrowth (SIBO)
  • Chronic headaches
  • Certain autoimmune conditions
  • Fibromyalgia
  • Colon diverticulitis
  • Exercise-induced GI symptoms
  • Skin conditions.

However, some experts caution that if you don’t have IBS, this restrictive diet might cause more harm than good. For example, many whole FODMAP-containing foods (e.g., vegetables, fruits, whole grains) also high in beneficial nutrients, such as phytonutrients, vitamins, minerals, and fiber including prebiotics, which are necessary for keeping our microbiome good and healthy.

Potential Benefits of the Low FODMAP diet

The key benefits of the low-FODMAP diet, not surprisingly, relate to an improvement in digestion-related complaints. These include:

  • A significant decrease in stomach pain and bloating (with 81% and 75% improvements reported, respectively).
  • Decrease of gas, diarrhea, and constipation.

It goes without saying that if you decrease those types of symptoms, your quality of life will also improve, and that’s exactly what has been reported.

Yet, because FODMAPs are found in numerous types of foods (including many foods that are typically considered “healthy”), it can be difficult at times to know what to eat and what to avoid. Because it can be incredibly restrictive and removes a variety of healthy foods from the diet, it is highly recommended that a low-FODMAP diet be used as a tool to raise awareness and assess your individual tolerance to FODMAP-containing foods. In fact, the first phase is essentially an elimination diet that should last no more than three to eight weeks. The theory is that this is enough time to give your digestive system an opportunity to heal and the gut microbiome the chance to rectify any imbalances.

The next phase is called the reintroduction phase, which is when you add one FODMAP-containing food at a time to see if you can identify specific foods that are causing your issues. Then, you can personalize the diet to your individual level of tolerance. That’s not to say that you can “never” eat suspect foods again; it’s just that you would have the awareness that eating certain foods may have consequences.

FODMAP Diet Guidelines

Stage 1: Weeks 1 – 3 to 8 (depending on how quickly you notice improvements in your symptoms): Elimination Phase—Strictly Limit or Avoid ALL high-FODMAP Foods

Stage 2: After Weeks 3 to 8: Reintroduction Phase—Add a small portion of 1 FODMAP-containing food at a time for one to three days and carefully observe symptoms to determine your “threshold level” of tolerance.

Stage 3: And beyond… Personalization—While increasing the variety of your diet and becoming more flexible, restrict only those FODMAP-containing foods you have found that you’re sensitive to. In other words, you may be able to eat a small amount of certain foods, you may want to avoid others altogether, and others can be eaten freely even if they contain moderate amounts of FODMAPs.

Low Fodmap Diet

Tips to Make Following the Low-FODMAP Diet Easier

If you have IBS, digestive-related complaints, or other issues mentioned above and want to find out if intolerances to FODMAPs are causing your issues, you may be ready to jump into the low-FODMAP Diet. But due to all of the restrictions, it may not be easy. Here are a few tips and suggestions to help you follow a low-FODMAP diet more easily and consistently:

  1. Because digestive issues can be caused by numerous issues, visit your healthcare professional first to rule out other conditions.
  2. Test out recipes and meal plans first before you start the diet. If you have a half dozen or so meals you know you’ll enjoy, it will be much easier to stick with the plan for the 3 to 8 weeks of the first stage.
  3. Plan to prepare foods at home throughout the diet, especially during the elimination phase. This includes not only meals but snacks.
  4. Stock up on low-FODMAP foods in advance. If you have the foods you can eat on hand, you won’t be searching for what to eat next once you’re hungry or eating something that’s not part of the plan.
  5. Learn to read labels (especially the INGREDIENTS), as many packaged foods have surprising ingredients that may not be part of your low-FODMAP plan.
  6. Let go of preconceptions. For one reason or another, you may have thought certain foods aren’t problematic, but with an open mind and awareness, you may notice that even the smallest amounts cause you pain. Use this time to be curious about how foods not only affect your digestion but how you feel (energized and focused or fatigued and foggy?), so you can make informed decisions in the future.
  7. Keep a food diary so you can track which foods are the culprits of your digestive woes and how much causes problems.

Is the Low-FODMAP Diet Right for You?

The low-FODMAP diet isn’t for everyone and should only be temporary until your digestive tract has the opportunity to heal and your gut microbiome has the chance to correct imbalances.

As always, whenever you start a new diet, it helps to work with a qualified healthcare professional. Someone who has experience with functional medicine and nutrition can help you navigate through this journey and continue to ensure your body is well-nourished as well. While the low-FODMAP diet can be really helpful for about 70% of the people with IBS, it isn’t recommended for the long-term. And because so many nutrient-dense foods are restricted, it is not recommended as the first line of defense for people already in good health.

To determine if this diet is one you should try, ask yourself the following questions:

  1. Do I have digestive issues like excess gas, bloating, stomach cramps or pain, diarrhea, or constipation on a regular basis?
  2. Have I been evaluated by a healthcare professional experienced in nutrition and diagnosed with IBS or another condition caused by food intolerances?
  3. Have celiac disease or other probably causes of digestive issues been ruled out?
  4. Have I been unable to manage symptoms despite following good health habits including stress reduction, eating a nutrient-rich diet, taking a quality probiotic, getting enough sleep, exercising regularly, and consuming enough water?
  5. Am I willing and able to take on such a strict dietary experiment?

If you are suffering from painful digestive symptoms, you’ve likely answered yes to all of the above. And a low-FODMAP diet may be worth trying.

If not, or after completing the 3 stages of the low-FODMAP diet, you are likely better off following a more lifestyle-based healthy eating approach such as the Mediterranean Diet, Paleo Diet Plan, DASH Diet, Keto diet, or others.


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