The Low FODMAP Diet for IBS: How to Identify Dietary Triggers and Improve Symptoms

Written by: Kelsey Schaffstall Young MS, RDN, LDN

What is IBS?

IBS, or irritable bowel syndrome, is characterized by gastrointestinal symptoms such as abdominal pain, cramping, gas, bloating, and changes in stool.2 These symptoms often stem from root causes such as dysmotility (abnormal contractions of the GI tract), visceral hypersensitivity (increased sensitivity of GI nerves), and brain-gut dysfunction.2

How is IBS treated?

Treatment for IBS should be multifaceted and may include diet, medications, psychological treatments, and stress management.2

One dietary strategy to treat symptoms of IBS is the low FODMAP diet, which was originally developed at Monash University. The low FODMAP diet is a short-term elimination diet meant to help identify dietary triggers and facilitate the transition back to a regular diet that excludes an individual’s trigger foods. Monash University research has shown that IBS symptoms such as pain, bloating, distention, bowel habits, and poor quality of life improve in 3 out of 4 people who follow a low FODMAP diet.1

What are FODMAPs?

FODMAPs are short-chain indigestible carbohydrates that can trigger symptoms of IBS. They attract water into the small intestine and serve as fuel for gut bacteria, causing fermentation and creating gas inside the intestine.1,3 FODMAP stands for fermentable (creates gas), oligosaccharides (type of fiber found in some grains, vegetables, and beans), disaccharide (lactose), monosaccharide (fructose or type of sugar found in fruit and processed foods), and polyols (sugar alcohols in sugar-free foods and some fruits and vegetables).1,3

What does the low FODMAP diet entail?

The low FODMAP diet consists of three phases: elimination, reintroduction, and personalization.3 The elimination phase consists of limiting high FODMAP foods for 2-6 weeks and monitoring symptoms closely. A dietitian will provide you with detailed instructions on how to build low FODMAP meals with specific portions of foods from each food group. Keep in mind that elimination diets are not recommended for those who struggle with disordered eating.

The reintroduction phase is meant to add high FODMAP foods back into your diet, one at a time, while closely monitoring symptoms to determine which foods trigger your individual symptoms. It is recommended that you only reintroduce two high FODMAP foods per week in order to accurately determine which foods exacerbate symptoms.

The final phase, or the personalization phase, allows you to return to a new normal diet with the most variety that can be enjoyed without triggering IBS symptoms.

How to be successful on a low FODMAP diet

In order to be successful on a low FODMAP diet, you should seek professional support from a Registered Dietitian who can guide you through the diet’s three phases. It’s also important to track your symptoms prior to starting the diet to document your baseline symptoms which will help you identify any improvements in symptoms during the elimination phase. Also spend substantial time planning prior to starting the low FODMAP diet to ensure that you have the ingredients necessary to follow a nutritious diet during the strict initiation phase. Finally, be sure to complete all three phases of the low FODMAP diet so that you can return to a normal diet once you identify your personal trigger foods. If you are interested in beginning a low FODMAP diet, you can find a Registered Dietitian to support you here.


  1. “FODMAPs and Irritable Bowel Syndrome.” Monash University, Monash University, Accessed 13 Nov. 2022.
  2. “Irritable Bowel Syndrome (IBS).” AGA GI Patient Center, American Gastroenterological Association, Accessed 13 Nov. 2022.
  3. “Low-FODMAP Diet.” AGA GI Patient Center, American Gastroenterological Association, . Accessed 13 Nov. 2022.

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