Can Fasting Cause Diarrhea? Tips to Prevent and Treat Fasting-Related Diarrhea

Can Fasting Cause Diarrhea?

Diarrhea is characterized by loose, watery stools that occur more frequently than usual. It's a common problem that most people experience from time to time. Diarrhea can be caused by infections, food intolerances, reactions to medications, and chronic conditions like irritable bowel syndrome. But can fasting also lead to diarrhea? Let's take a closer look.

How Fasting Affects the Digestive System

Fasting is the practice of voluntarily abstaining from some or all food and drink for a period of time. Intermittent fasting, alternate day fasting, and extended fasting periods of 24-48 hours are some popular fasting regimens.

When you fast, especially for longer periods, it can disrupt the normal processes of the gastrointestinal (GI) tract. Here's a quick overview:

• Reduced stomach acid production - Stomach acid helps digest food and kill harmful bacteria. Lower acid levels may allow more bacteria to survive.
• Slower movement of food and waste - Fasting slows motility, allowing more time for excess water to be absorbed from food waste.
• Altered gut flora - Harmful bacteria may flourish with less competition from nutrient-metabolizing bacteria.
• Dehydration - Fluid intake is reduced, which can lead to dehydration and constipation.

These changes to the digestive process during fasting may stimulate diarrhea in some people.

How Fasting Can Cause Diarrhea

Here are some of the specific ways fasting may trigger diarrhea:

1. Reaction to the refeeding process

After a fast, eating food again is called refeeding. This process can overwhelm the digestive system, especially if people break their fast by overeating. The increase in fats, carbohydrates, and other nutrients may pull fluid into the intestines and accelerate food movement through the gut, resulting in diarrhea.

2. Change in gut bacteria

With less food available, gut flora populations shift during a fast. Beneficial bacteria decline while harmful bacteria may thrive. Diarrhea-causing bacteria like Salmonella, E. coli, Clostridium difficile, Staphylococcus aureus, and viruses can then colonize the gut, producing toxins that irritate the intestines.

3. Altered electrolyte levels

Vomiting and diarrhea cause the body to lose fluids and electrolytes like sodium and potassium. Fasting can have a similar effect. The imbalance of electrolytes can result in watery stool.

4. Coffee, tea, and other fluids

Some people allow certain beverages during a fast. Caffeinated and alcoholic drinks are diuretics that can cause loose stools. High sugar drinks can also cause diarrhea when gut bacteria feed on the excess sugars.

5. Food reactions

After fasting for a while, the digestive system may be more sensitive to different foods. Eating something your body doesn't agree with could cause an acute bout of diarrhea.

Who Is Most At Risk?

Diarrhea as a result of fasting may be more likely in the following circumstances:

• Extended fasting - diarrhea risk increases with longer fasts of several days compared to intermittent fasting
• History of GI issues - pre-existing irritable bowel syndrome or inflammatory bowel disease
• Elderly - decreased immune function and motility
• Recent use of antibiotics - can disrupt gut flora leading to infection
• Overeating when breaking a fast - eating too much or fatty, sugary foods too quickly
• Consuming trigger foods - dairy, caffeine, alcohol, high-fiber foods

If you already have frequent loose stools or a sensitive digestive system, take extra precautions when fasting.

Tips to Prevent Fasting-Related Diarrhea

You can reduce your risk of diarrhea during or after fasting by following these guidelines:

Break your fast slowly

Don't overwhelm your digestive tract after a fast. Gradually ease back into eating with small portions of bland, low fiber, low fat foods. Soup, broth, boiled rice, toast, crackers, bananas, and applesauce are gentler options.

Stay hydrated

Drink plenty of fluids, like water, diluted fruit juice, or oral rehydration solutions. However, avoid drinks containing caffeine or alcohol which can make diarrhea worse.

Choose low FODMAP foods

A low FODMAP diet limits carbohydrates that may ferment in the gut and draw water into the intestines. Try avoiding lactose, fructose, fructans, galactans, and polyols.

Take probiotic supplements

Probiotics contain beneficial bacteria that can improve gut health and reduce the risk of diarrhea. Look for broad spectrum probiotic supplements with strains like Lactobacillus and Bifidobacterium.

Manage chronic health conditions

Work with your healthcare provider to keep chronic GI issues like IBS, IBD, SIBO, or celiac under control. These require special diets that should be resumed after fasting.

See a doctor if it persists

Diarrhea lasting more than 2 days may require medical attention. Seek care if you have severe symptoms like bloody stool, high fever, or signs of dehydration.

What To Do If You Get Diarrhea While Fasting

Mild fasting-related diarrhea will often resolve on its own once you start eating normally again. But you can try these remedies to get relief faster:

Stop the fast

Ending the fast is the quickest way to relieve diarrhea and other GI issues. Gradually reintroduce bland foods and beverages.

Take an anti-diarrheal medication

Over-the-counter anti-diarrheal agents like loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol) can help curb diarrhea. Use as directed.

Replace lost electrolytes

Drink oral rehydration solutions which contain essential electrolytes. You can also try eating briny foods like miso soup, pickles, olives, and potato chips.

Eat binding foods

Foods that are high in starch and pectin absorb fluid and firm up stool. Try bananas, white rice, applesauce, toast, oatmeal, or potatoes.

Avoid problematic foods

Certain foods and drinks may aggravate diarrhea, like caffeine, alcohol, greasy foods, spicy foods, and high-fiber foods. Avoid these until symptoms resolve.

Take probiotics

Probiotic supplements can shorten the duration of acute diarrhea. Look for Lactobacillus strains like rhamnosus, casei, or acidophilus.

Practice self-care

Get extra rest, stay hydrated, and wash your hands frequently when you have diarrhea. Contact a doctor if symptoms are severe or persist beyond 48 hours.

When To See A Doctor

In most cases, fasting-related diarrhea is mild and will improve in a day or two. But contact your doctor if you experience:

• Diarrhea lasting more than 2 days
• More than 3-4 loose stools per day
• Severe abdominal pain and cramping
• Blood or mucus in the stool
• High fever over 101F (38C)
• Signs of dehydration - extreme thirst, dry mouth, infrequent urination

Some cases of diarrhea require prescription medication or intravenous fluids. Seek prompt medical care for serious symptoms, especially if you have a weakened immune system or chronic health issues.

When Fasting May Not Be Recommended

While fasting may potentially cause diarrhea in some instances, those with certain medical conditions should avoid fasting altogether or only fast with medical supervision. This includes people with:

• Inflammatory bowel diseases like Crohn's or ulcerative colitis
• Irritable bowel syndrome (IBS)
• Celiac disease
• Eating disorders
• Gastroparesis or slow stomach emptying
• Pregnancy or breastfeeding
• Type 1 diabetes
• Gout
• Malnutrition

People who are underweight or frail, elderly, or have other chronic diseases should also consult their doctor before fasting. Certain populations require special dietary requirements that may conflict with fasting.

The Bottom Line

Fasting can definitely cause diarrhea in some people due to changes it triggers in the gastrointestinal tract. The most common causes are gut flora imbalance, food reactions, and electrolyte disturbances. Fortunately, fasting-related diarrhea is usually mild and temporary.

You can reduce the risk of diarrhea while fasting by staying hydrated, breaking your fast gradually, and being cautious with trigger foods and beverages. If diarrhea persists or becomes severe, stop fasting and see your doctor. With some care and patience, most people can fast comfortably without diarrhea.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.