Diarrhea After Eating Fatty Foods: 5 Causes & Tips (By Dr. Farahat).

✅ Evidence-Based.

✅ By Dr. Farahat.

Many conditions can lead to diarrhea after eating fatty foods. The most common causes are simple conditions such as exaggerated gastrocolic reflex and irritable bowel syndrome. Other causes may include gallbladder and pancreatic problems or bile acid diarrhea.

To learn more about each of the conditions causing you diarrhea after eating fatty foods, keep reading the detailed article on how to suspect and deal with each condition.

Table summary of the causes of diarrhea after eating fatty food

  • The majority of cases are either due to exaggerated gastro-colic reflex Or irritable bowel syndrome.
  • Note that those are the causes of CHRONIC OR RECURRENT diarrhea after eating fatty foods. 
  • Always consult your doctor if you experience one of the red signs enlisted below.
Diarrhea after eating fatty food causes

How to suspect (symptoms)? and how to deal?

1- Exaggerated Gastro-colic reflex: due to 

  • stress, 
  • fatty foods, or 
  • large meals
  • It is the most common cause of diarrhea after eating fatty food.
  • A natural response of your colon to a full stomach with food.
  • It can be normally exaggerated by eating large meals or fatty food, drinking large amounts of fluid, or stress.
  • Usually, it is a mild attack of diarrhea after fatty foods, with no severe abdominal pain. No diarrhea between meals.
  • You can control the condition by adjusting your diet habits, usually, you need no treatment.
2- irritable bowel syndrome
  • Another common condition of diarrhea after eating fatty foods (IBS-Diarrhea).
  • IBS is characterized by abdominal pain associated with defecation, change in stool frequency, or stool form.
  • Many people don’t know they have IBS, because they don’t seek medical advice. If you have symptoms consistent with IBS, consult your doctor.
  • Learn how is IBS diagnosed here.
  • Diet, antidiarrheals, and antispasmodics and stress management can control your case.
3- removal of your gallbladder
  • Postprandial diarrhea can occur in up to 20% of people undergoing gallbladder removal.
  • Diarrhea can intermittently occur after eating fatty food or become continuous.
  • Usually associated with bloating, abdominal discomfort, or pain.
  • Imodium, cholestyramine, and eating small non-fatty meals can help.
4- Bile acid diarrhea (Malabsorption)
  • A relatively common and underdiagnosed condition.
  • Caused by problems in the processing of secreted bile acid inside your intestine leading to diarrhea.
  • It usually occurs after eating fatty foods usually associated with severe urgency and soiling accidents.
  • Diagnosis is quite difficult, treatment by a bile acid binder drug called cholestyramine may improve the condition.
5- Exocrine Pancreatic insufficiency (EPI)/chronic pancreatitis.
  • Common in alcoholics and people with chronic pancreatitis.
  • The condition may be mild and diarrhea occurs only after you eat fatty foods.
  • More severe disease can present with severe greasy diarrhea, abdominal pain, bloating, weight loss, and vitamin deficiency.
  • Suspect if you have a history of pancreatitis.
  • Treatment is usually by the replacement of deficient pancreatic enzymes.
*when to see a doctor.
  • In most cases, diarrhea is mild and its cause is simple. you don’t need to see a doctor.

See a doctor IF you have any:

  • Bloody stool or continuous greasy (fatty stool).
  • Recurrent abdominal colics for an unknown cause.
  • Explosive diarrhea after eating with intense urgency or soiling accidents.
  • Weight loss
  • Continous diarrhea after the removal of your gallbladder.

1- Exaggerated gastro-colic reflex (The most common cause of diarrhea after eating fatty foods).

Gastro-Colic reflex is a natural process inside your body. When you start eating and your stomach receives food, this sends signals to your colon to increase its motility. And the result is the urge to poop immediately after eating.

The gastro-colic reflex can be normally exaggerated by:

  • Eating large meals.
  • Fatty meals (especially with healthy fats).
  • Drinking a large amount of cold liquid at one time.
  • Stress and anxiety

Also, it can be abnormally exaggerated, as with some people with irritable bowel syndrome (reference).

exagerated gastrocolic reflex cuases diarrhea after eating fatty foods

Symptoms (how to suspect exaggerated gastro-colic reflex):

Exaggerated gastro-colic reflex is considered a common cause of diarrhea after eating fatty foods. It is usually a mild, non-harmful condition. Suspect it if you have:

  • Urge to poop immediately after eating, especially if diarrhea occurs after eating fatty foods, large meals, or if you have stress.
  • Diarrhea only after eating, not when you are fasting.
  • You may experience mild cramps or discomfort after eating. The cramps immediately go away after you poop.
  • the diarrhea is usually yellow in color and greasy.
  • No severe or persistent colics, 
  • No history of gallbladder removal or problems.

How to deal:

  • Try to eat fewer amounts of healthy fat, and stay away from unhealthy fat.
  • Avoid large meals.
  • Avoid caffeine and drinking large amounts at one time.
  • If the condition persists, consult your doctor, it may require some investigation to exclude similar conditions such as irritable bowel syndrome and bile acid diarrhea.

Learn more about Gastro-colic reflex and diarrhea after eating fatty foods:

Wikipedia: Gastrocolic reflex.

Verywellheath: your gastrocolic reflex with IBS.

2- Irritable bowel syndrome (IBS).

Irritable bowel syndrome is a chronic functional syndrome affecting your gut. It is a common condition that approximately affects 10-15% of the population (reference). Many people have symptoms consistent with IBS. But a large subset of them doesn’t seek medical advice.

If you have diarrhea after eating fatty foods, this can be undiagnosed irritable bowel syndrome. Consult your doctor if you suspect you have irritable bowel syndrome.

How to suspect if IBS is the cause of diarrhea after eating fatty foods?

With IBS the symptoms are not restricted to diarrhea after eating fatty foods. But other symptoms also present: (reference)

  • Abdominal pain (cramps) is a cardinal feature of irritable bowel syndrome.
  • The abdominal pain is usually recurrent (at least one day per week) in the past 3 months.
  • Periods of flare-ups alternate with periods of remissions.
  • The onset of pain is associated with defecation, change in stool consistency, or stool frequency.
  • Diarrhea after eating fatty meals is more commonly associated with the IBS-Diarrhea subtype, and it can also occur in other types of IBS (IBS-Mixed and IBS-Unspecified).
  • The condition may increase with stress and anxiety.
  • The diarrhea is not restricted to fatty foods and may be caused by a variety of foods such as FODMAPs and lactose.

diarrhea after eating fatty foods can be due to IBS

How to deal?

  • If you are not yet diagnosed with IBS: contact your doctor if you suspect you have IBS. 
  • If you already have IBS, it is probably the cause of diarrhea after eating fatty foods. You can decrease postprandial diarrhea by:
    • Avoid heavy meals, fatty meals, and caffeine.
    • Manage your stress and anxiety.
    • Avoid lactose and FODMAPs.
    • You can use over-the-counter medications for IBS pain relief, and IBS diarrhea. Check our resources page for options.
    • Consult your doctor if there is no improvement.

3- Removal of your gallbladder.

According to Dr. Michael from mayoclinic.org, diarrhea can occur in up to 20% of people undergoing gallbladder surgery. It is usually self-limiting, mild (usually after meals). In certain patients, it may last for years. (reference).

GB fatty diarrhea postbrandial

Image Data source

The function of your gallbladder is to store bile and releases it during meals to digest fat. This on-demand secretion of bile becomes interrupted after the removal of your gallbladder.

The exact cause of diarrhea after GB removal is still not clear. By excess transport of bile into the intestine may act as a laxative, or presence of some sort of fat malabsorption.

How to suspect?

  • If you have a history of gall bladder removal and diarrhea onset after removal of the GB. 
  • Also, diarrhea may start before surgery during the cholecystitis stage and don’t resolve after surgery.
  • Other symptoms include stomach cramps, gas, and bloating.
  • Diarrhea can occur occasionally after eating fatty foods or become continuous and it may be yellow.

How to deal?

  • Eating smaller meals, decreasing fat in your diet might help alone.
  • Talk with your doctor about some medications that may relieve diarrhea as Immodium (loperamide) or cholestyramine.

4- Bile acid diarrhea / Fat intolerance.

Bile acid malabsorption or bile acid malabsorption refers to diarrhea caused by abnormal processing of bile acids by the digestive system.

Bile acid is secreted from the liver, stored in the gallbladder, and released into your intestine to help fat digestion and absorption.

The bile acids get reabsorbed again from your intestine. Problems in absorption or processing of bile acids by your body can lead to occasional diarrhea after fatty foods. The condition may become more severe and cause chronic diarrhea.

The condition is more common than you think (reference).

Symptoms (how to suspect?)

  • Diarrhea (usually yellow color): after eating fatty foods, or even chronic diarrhea at any time (not only after meals).
  • A special feature of diarrhea is that you may have severe urgency, the risk of stool leakage may occur especially in older ages.
  • It is usually a watery type of diarrhea, more frequent in obese people.
  • Bloating, indigestion may be present.

How to deal?

  • The diagnosis of Bile acid diarrhea may be quite difficult for yourself and your doctor.
  • If you always have diarrhea with intense urgency tell your doctor about that.
  • Some doctors may request special tests or endoscopy, others may run a therapeutic test by giving you the treatment.
  • The best treatment is a drug that binds to the bile acid inside the intestine and prevents its bad effects (cholestyramine )
  • Decrease the consumption of fatty foods. Go for the healthier fats present in avocados, fatty fish, and nuts.

Learn more about Bile acid diarrhea: source1, source2

5- Exocrine Pancreatic insufficiency (EPI)/chronic Pancreatitis.

Your pancreas secretes enzymes that digest food. For example:

  • Lipase enzymes: help fat digestion.
  • Amylase enzyme: help carbohydrate digestion.
  • Protease enzyme: help protein digestion.

When your pancreas runs into a problem, it will not secrete sufficient amounts of these enzymes. This leads to maldigestion and problems such as diarrhea after eating fatty foods (as with lipase deficiency), chronic stomach pains.

The conditions that may lead to Exocrine Pancreatic Insufficiency (EPI): (reference)

  • Chronic pancreatitis: recurrent inflammation and damage to the pancreas lead to permanent loss of the cells secreting pancreatic enzymes. One of the most common causes of chronic pancreatitis is alcoholism.
  • A rare condition called cystic fibrosis, which is an inherited genetic disease that affects the lungs, the digestive and reproductive systems and leads to pancreatic insufficiency.
  • Operative resection of parts of your small intestine, pancreas, stomach.
  • Obstruction of the pancreatic duct.
  • Other diseases affecting the pancreas (rare): such as hereditary hemochromatosis, Shwachman-Diamond syndrome.

Symptoms (how to suspect?) 

  • Mild diseases may have no symptoms at all. Or it may have mild symptoms such as abdominal discomfort, mild diarrhea after eating fatty foods, carbohydrates, or proteins.
  • Moderate to severe disease: Maldigestion and diarrhea after eating fatty foods, carbohydrates, and proteins.
  • Fatty diarrhea with loose greasy stool: occurs in severe cause with loss of more than 90% of pancreatic function.
  • Bloating, flatulence, stomach cramps, and weight loss.
  • Other symptoms of chronic pancreatitis such as recurrent mid-epigastric pain may be present.

How to deal?

  • The condition is not common, you don’t have to over-think It if you are an alcoholic. Consult your doctor about the condition if you have symptoms consistent with the above list.
  • Your doctor suspects pancreatic insufficiency if you have troublesome chronic abdominal pain, greasy diarrhea, bloating, or a history of pancreatitis.
  • Your doctor confirms the condition by imaging of your pancreas (abdominal ultrasonography or CT), and it may perform some stool or blood tests.
  •  The main treatment is replacement with external pancreatic enzyme supplement after confirming the condition.
  • Mild symptoms may pass undiagnosed, you may benefit from controlling the number of fatty foods to stop occasional mild diarrhea after eating fatty foods.

Learn more about pancreatic insufficiency: source1, source2

Red signs: when to see a doctor if you have diarrhea after eating fatty foods?

Diarrhea after eating fatty foods often occur due to exaggerated gastrocolic reflex or IBS. But other less common medical conditions may cause the same postprandial diarrhea.

See your doctor if diarrhea after eating fatty foods is associated with one or more of the following:

  • Severe urgency or explosive diarrhea after eating.
  • Soiling accidents, losing control over your stool.
  • Weight loss.
  • Fever, or vomiting.
  • Continuous diarrhea after the removal of your gallbladder.
  • Consistent greasy type of stool.
  • Symptoms consistent with IBS: recurrent abdominal pain associated with defecation, change in stool form, or frequency for at least one time a week in the past 3 months.
  • Bloody diarrhea.