Can intermittent fasting be beneficial for IBS?

Share on Pinterest

There is currently insufficient research to understand the effects of intermittent fasting on IBS.

A 2020 study in Iran examined the effects of snack and meal frequency on IBS symptoms. It found no significant link between meal or snack frequency and IBS symptoms.

However, it found a 32% lower risk of IBS symptoms among females who ate three main meals per day compared with those who ate one main meal per day. People with overweight or obesity who had three main meals daily also had a reduced risk of IBS.

According to the study, previous research also suggests a link between IBS and eating habits, such as rapidly consuming food and regular or irregular eating.

Read more about eating one meal per day.

According to a 2018 review, an imbalance in the gut microbiome may play a part in causing IBS. Research suggests that treatments to address this imbalance may benefit people with IBS.

A 2021 study looked at the effects of Ramadan-associated fasting and found that intermittent fasting may help remodel the gut microbiome and upregulate the bacteria Lachnospiraceae, leading to health benefits.

Its authors suggest that previous research has linked higher levels of Lachnospiraceae to improvements in inflammatory bowel disease (IBD), as well as better mental health and a reduced rate of cancer.

The migrating motor complex (MMC) occurs during periods of fasting. It involves waves of electrical activity in the gastrointestinal tract in regular cycles. The MMC helps move food through the digestive system into the colon, playing a key role in digestion and gut motility.

A weakened MMC process can cause small intestinal bacterial overgrowth (SIBO), an excess of bacteria in the small intestine that leads to fermentation and can cause IBS symptoms. Many people with IBS may also have SIBO.

Read about the link between stomach issues and digestive disorders.

According to a 2020 study, people with IBS may skip meals more frequently than those without IBS.

The researchers suggest that skipping meals may have a negative effect on IBS due to a reduction in the gastro-colonic reflex, which increases gastrointestinal motility and supports digestion. Issues with this reflex may be associated with severe constipation.

They also state that increasing meal frequency may help improve the gastro-colonic reflex and reduce IBS symptoms, although researchers need to perform further studies to confirm this link.

Intermittent fasting may lead people to eat fewer but larger meals. The International Foundation for Gastrointestinal Disorders (IFFGD) recommends that people with IBS try eating smaller meals more frequently throughout the day rather than a few larger meals. This is because large meals may overstimulate the gut and trigger IBS symptoms.

The IFFGD also advises that people with IBS do not skip breakfast, especially if they have constipation. Breakfast is the meal most likely to support food moving through the colon and stimulate a bowel movement.

If intermittent fasting leaves people feeling hungry, it may cause discomfort. People with IBS may be more sensitive to pain and sensations in the gastrointestinal tract.

Intermittent fasting may also not be suitable for certain groups of people, including those who:

• are pregnant or breastfeeding
• are under the age of 25
• are taking insulin or other medications for diabetes
• need to take any medication with food
• have a seizure disorder
• work in a job that involves heavy machinery or night shifts

There are several methods of intermittent fasting. People who wish to try it can choose the best option for their lifestyle, energy requirements, and IBS symptoms.

5:2 fasting

This involves a person eating a very low calorie diet for 2 days per week and eating their regular diet on the remaining days.

Learn more about the 5:2 method.

The 16:8 method

People using this method fast for 16 hours in a day, with 8 hours allowed for eating. Alternatively, they may choose to fast for 18 hours and have a 6-hour window for eating.

Learn more about the 16:8 method.

Eat-stop-eat

The eat-stop-eat method of intermittent fasting involves doing a 24-hour fast 1–2 times a week. People can eat as they choose to on the other days of the week. The term for this type of fasting is periodic prolonged fasting or intermittent calorie restriction.

Learn more about fasting for 24 hours.

Because there is little scientific evidence regarding the effects of intermittent fasting on IBS, it is unclear when or if people may see an improvement in symptoms using this method.

Studies vary widely in terms of the duration of intermittent fasting and the time frame of its effects, ranging from 4–8 weeks to 12 months.

Other ways of managing IBS symptoms may include:

• Diet changes: People may eliminate food triggers, consider eating a low-FODMAP diet, and increase their fiber intake.
• Exercise: Regular physical exercise may help reduce IBS symptoms.
• Sleep: It may help to get enough quality sleep each night and stick to a regular sleep schedule.
• Relaxation: Managing stress may help relieve IBS symptoms. Relaxation techniques, time management adjustments, and lifestyle changes may all help.
• Probiotics: Certain probiotics may help support the gut microbiome and address imbalances.

Read about complementary therapies for IBS.

The effects of intermittent fasting on IBS are unclear. Some research suggests intermittent fasting may support the gut microbiome and gut motility. Other studies suggest eating smaller meals more frequently may be more beneficial for managing IBS symptoms.

If people want to try intermittent fasting for IBS, they can talk with a healthcare professional about whether it may be suitable for them.