Living with irritable bowel syndrome (IBS) is the way of life for 12 percent of Americans, research estimates.

While the exact cause of IBS is unknown, the symptoms of abdominal discomfort, intermittent abdominal pain, diarrhea, constipation, bloating, and gas are well-known to those who deal with this gastrointestinal (GI) disorder.

With so many aggravating symptoms that can also be unpredictable, many people wonder if lifestyle modifications such as fasting can help manage IBS.

One lifestyle modification that sometimes comes up when discussing IBS is fasting. The two forms of fasting related to IBS are intermittent fasting and long-term fasting.

With intermittent fasting, you alternate between periods of eating and periods of not eating.

One popular method of intermittent fasting involves restricting your eating to an eight-hour block of time. For example, your food consumption would happen between 1:00 p.m. and 9:00 p.m.

Long-term fasting involves restricting food and possibly fluids for an extended period of time (i.e., 24 to 72 hours).

According to Ryan Warren, RD, nutritionist at NewYork-Presbyterian Hospital and Weill Cornell Medicine, the benefit or lack thereof of fasting on IBS greatly depends on the type of IBS as well as the cause of IBS.

“Patients who suffer from IBS experience a wide array of symptoms due to a variety of underlying etiologies,” Warren said. “This must always be taken into consideration before making clinical recommendations.”

However, the research on fasting as a way to manage IBS is minimal. Newer studies are needed to really know whether fasting positively affects IBS.

What’s migrating motor complex, and how is it related to fasting with IBS?

Migrating motor complex (MMC) is a distinct pattern of electromechanical activity observed in GI smooth muscle during the times between meals, like periods of fasting.

Warren says to think of it as three phases of natural “cleansing waves” in the upper GI tract that occur every 90 minutes between meals and snacks.

It’s this theory that some people say contributes to the positive effects of fasting with IBS. But while there’s plenty of research on MMC itself, there’s very little to no scientific evidence to support its role in minimizing the symptoms of IBS.

Why fasting might improve IBS

If your symptoms occur as a response to eating — such as gas, bloating, or diarrhea after eating — Warren says that longer fasting periods (or structured meal spacing) may be useful in managing these types of symptoms.

That’s because fasting patterns can help promote the MMC mechanism. Warren says that can improve certain IBS symptoms, particularly when small intestinal bacterial overgrowth is the suspected or confirmed cause.

Studies show that suboptimal MMC function is correlated with small intestinal bacterial overgrowth (SIBO), which can often be a root cause of IBS,” Warren explained.

“Fasting patterns can improve gastrointestinal motility associated with the MMC, which allows intestinal contents to move efficiently through the GI tract,” she added.

This optimal motility is significant, Warren says, because it helps reduce the occurrence of SIBO and excess fermentation of food contents that may ultimately trigger IBS symptoms.

“Fasting is also linked to anti-inflammatory, gut-healing benefits through its proposed activation of autophagy (a natural process by which damaged cells degrade and rejuvenate themselves),” Warren said. This, in turn, may have positive effects on IBS symptoms.

Additionally, Warren says fasting may be linked to favorable alterations in the gut microbiota. “Maintaining a properly balanced gut microbiota (i.e., with a diverse range of beneficial species) is paramount in managing IBS,” she added.

According to Warren, fasting may nothelp IBS in cases where long periods of fasting ultimately lead to the consumption of larger portions of food at the end of the fast.

“Excess volume of food contents in the upper GI tract can trigger symptoms in some individuals,” Warren said. “Fasting, therefore, may significantly backfire if it becomes a justification for excess intake later on in the day.”

Warren says that in her work with patients who exhibit certain kinds of gut hypersensitivity, hunger sensations or lack of food can be a trigger.

She explains that certain IBS symptoms can occur in response to the stomach being empty in these individuals. Symptoms can include:

  • pain
  • cramping
  • nausea
  • stomach rumbling
  • acid reflux

“For these patients, small, frequent meals may be recommended as an alternative to structured meal spacing or long fasting periods,” Warren said.

Since the research and scientific evidence on fasting is scarce, it’s important to look at other ways to treat IBS.

The good news is there are several lifestyle modifications as well as medications to consider that can treat IBS symptoms:

Diet modifications

One of the first places to start treating IBS is with your diet. Identifying and avoiding trigger foods is key with managing symptoms.

Depending on the severity of your symptoms, this may include foods with gluten and a type of carbohydrate called FODMAPs. Foods high in FODMAPs include certain fruits and veggies, dairy, grains, and beverages.

Eating smaller meals at regular times is also a common suggestion, which contradicts the idea of fasting. That said, there’s more research on the consumption of regular meals than there is on fasting.

Additionally, your doctor may recommend increasing your intake of fiber and upping your fluids.

Physical activity

Participating in regular exercise and physical activities you enjoy can help reduce stress, which helps with IBS symptoms.

Reduce stress levels

Practicing stress-reducing activities, such as deep breathing, relaxation, meditation, and physical activity, can help you relax your muscles and reduce stress. Some people also find success with talk therapy for managing stress levels.


Probiotics are an over-the-counter supplement your doctor may recommend to help restore gut flora.

The idea behind probiotics is that you can introduce live microorganisms to your system that can enhance your health. Talk to your doctor about which probiotics and dosage would be good for you.


Your doctor may prescribe a medication to help with IBS. Some of the more common ones help:

  • relax the colon
  • ease diarrhea
  • help you pass stools easier
  • prevent bacterial overgrowth

Your doctor will first review your health history and symptoms. They will want to rule out any other conditions before moving forward.

If there are no concerns about other health issues, your doctor may recommend testing for gluten intolerance, especially if you’re experiencing diarrhea.

After these initial screenings, your doctor may use specific diagnostic criteria for IBS. This includes the Rome criteria, which assesses things like abdominal pain and pain levels when passing stool.

Your doctor may also request blood work, a stool culture, or a colonoscopy.

This is the million-dollar question, and one with no definitive answer. That said, experts continue to look at certain contributing factors, including:

  • severe infections
  • changes in bacteria in the gut
  • inflammation in the intestines
  • overly sensitive colon
  • poorly coordinated signals between the brain and intestines

Additionally, certain lifestyle factors can trigger IBS, such as:

  • the foods you eat
  • an increase in your level of stress
  • hormonal changes that accompany the menstrual cycle

While the severity of symptoms can vary, there are a few common signs to look for when identifying IBS, such as:

  • pain in abdomen
  • changes in bowel movements
  • diarrhea or constipation (and sometimes both)
  • bloating
  • feeling like you haven’t finished a bowel movement

While some people are finding relief from IBS symptoms by fasting, the research and scientific evidence is minimal. More studies are needed.

If you’re considering fasting, consult with your doctor or a registered dietitian. They can help you decide if this is the right approach for you.