Diarrhea after eating, also known as “postprandial diarrhea,” is a very specific subset of bowel trouble.
Normally, it takes anywhere from 12 to 48 hours, sometimes more, for your body to pass stool in response to something you have recently eaten.
Experiencing bowel movements immediately after eating a meal or within a few (under three to five) hours is therefore unusual and a sign that something is causing your intestines to move much faster than normal.
In This Article:
- Defecation Reflexes: Understanding Bowel Movements after Eating
- What Causes Diarrhea after Eating (Postprandial Diarrhea)?
- Causes of Bowel Movement after Eating a Meal
- Recognizing the Symptoms of Diarrhea after Eating (Postprandial Diarrhea)
- How to Treat Diarrhea after Eating
- Preventing Diarrhea after Eating (Lifestyle Changes for Diarrhea after Eating)
- When to Contact a Doctor
- Ditch Diarrhea after Meals by Improving Digestion
Defecation Reflexes: Understanding Bowel Movements after Eating
After food is digested, the resulting feces come to rest in the colon in a highly watery state. Over time, much of the water gets reabsorbed by the body and the feces firms up into a more solid and familiar shape.
As more mass is added to the feces, it will eventually reach a point where it presses on one of the nerves that govern defecation. This triggers a series of responses known as the defecation reflexes.
There are two main defecation reflexes: the myenteric defecation reflex and the parasympathetic defecation reflex. The former leads to muscle contractions to push stool down towards the rectum, eventually signaling the sphincter to relax so that stool can pass.
The parasympathetic defecation reflex features a similar process in terms of functionality, with the major difference being control. For example, if you have an urge to go to the bathroom but there is no toilet around, you can tighten your sphincter muscles using the parasympathetic defecation reflex.
In some cases, however, it is possible to lose this reflex. When it’s lost, incontinence can occur, or you can experience more severe urges to go to the bathroom.
In the case of diarrhea after eating, the defecation is triggered by other reflexes up the gastrointestinal tract called the gastrocolic reflex and duodenocolic reflex.
Gastrocolic reflex: This is a natural reflex your body has once food enters your stomach, and stimulates contractions in the gastrointestinal tract. Its job is to communicate to the colon that there is waste ready to be removed to make room for more food. Some people may have a very sensitive gastrocolic reflex that sends them running to the bathroom almost immediately after eating. Although not an independent condition, it is something common to people with irritable bowel syndrome, or IBS.
Duodenocolic reflex: This reflex takes place when the duodenum becomes distended a short while after eating. This can trigger a bowel movement or an upset stomach. The duodenum is the first and shortest segment of the small intestine and receives partially digested food. If it’s triggered suddenly, it could push food through the digestive system a little faster.
Whether these two are involved in your specific situation will naturally depend on what the underlying cause is.
What Causes Diarrhea after Eating (Postprandial Diarrhea)?
Diarrhea is divided into acute and chronic conditions. Acute means sudden-onset and usually refers to short-lived or one-off instances. If you continue to experience diarrhea for around three weeks or more, it moves into chronic territory. This distinction is important since some diarrhea causes fall into only one category, so knowing the differences between them can help narrow the diagnosis.
Chronic Causes of Diarrhea after Eating (Postprandial Diarrhea)
In addition to the time period, chronic diarrhea also needs to meet the criteria of at least three watery stools per day, typically, but not always, occurring after meals.
Irritable bowel syndrome (IBS): Some sufferers of IBS find that their gut is so sensitive they can suffer diarrhea shortly after eating. Research has revealed that a sizeable number of people diagnosed with IBS have exaggerated gastrocolic reflex responses to meals. This appears to be connected to abnormal levels of two hormones that are responsible for regulating the speed of the digestive system. The hormones are cholecystokinin and motilin.
Irritable bowel syndrome – diarrhea (IBS-D): One form of IBS in particular is IBS-D. Simply put, IBS-D is when a person experiences all the pain and discomfort associated with IBS, but with the addition of high diarrhea frequency. Bowel movements may not always be watery or loose, and there may be increased urges to go the bathroom.Research has also indicated that a small percentage of individuals with IBS-D respond to treatment with digestive enzymes. These people may have issues producing enough digestive enzymes to help them break down and digest food, which may contribute to postprandial diarrhea. When the pancreas does not produce enough digestive enzymes, it’s known as pancreatic exocrine insufficiency.
Inflammatory bowel disease: Inflammatory bowel disease is another potential cause for diarrhea after eating. Two more well-known forms of the condition are Crohn’s disease and ulcerative colitis. The difference between these conditions is that Crohn’s can involve any part of the gastrointestinal tract, while ulcerative colitis only affects the colon. Inflammation in the digestive system is a bit of a mystery, but it may be tamed by dietary adjustments.
Celiac disease: This is an autoimmune reaction to eating gluten, one of which can be a sudden bout of diarrhea. Due to the effects of celiac disease and the retention of gluten, the resulting stool will be more likely to float or be strong-smelling.
Bile acid malabsorption (BAM): Bile acids are produced by the gallbladder to help you digest fats. They are normally reabsorbed but if this doesn’t fully happen, the acids will stick around and annoy your intestines. BAM is triggered by surgery or digestive illness, but sometimes it has no known origin.
Dumping syndrome: This is a possible complication of certain weight-loss surgeries. Dumping syndrome causes the stomach to empty too quickly into the small intestine, triggering the duodenocolic reflex.
Microscopic colitis: Although the cause is unknown, microscopic colitis involves inflammation in the tiny cells that line the intestine. It can be very difficult to diagnose because the cells can only be viewed under the lens of a microscope. It may sound similar to ulcerative colitis, but it is a unique condition that requires an independent diagnosis.
Colon cancer: If you have chronic diarrhea, you can take some comfort in the fact that it’s likely not colon cancer. Colon cancer would be marked by other symptoms like constipation, blood in the stool, changes in bowel movement frequency, unexplained weight loss and fatigue, or an anemia diagnosis.
Gallbladder removal: If you’ve undergone surgery to remove your gallbladder, you may experience diarrhea after eating for a temporary period following the procedure. It could be due to bile acids not being regulated in the small intestine, which may lead to contractions. If it remains an ongoing problem for an extended period following surgery, talk to your doctor.
Endocrine disorders: Certain hormonal disorders can lead to chronic diarrhea, especially if they’ve resulted in nerve damage to the digestive tract. Endocrine conditions that carry this risk include diabetes and hyperthyroidism.
Research suggests that an overactive thyroid, known as hyperthyroidism, may be linked to diarrhea. If you’ve experienced other symptoms of hyperthyroidism—elevated blood pressure, irritability, unexplained sweating, weakness—diarrhea may be another side effect. Some of the ways it could impact digestion include:
- Dietary fat malabsorption
- Intestinal hypermobility (moves food through very fast)
- Hypersecretion of bile
- Increased intestinal transit time
It’s not clear how diabetes can influence the likelihood of chronic diarrhea; however, there are some connections. Potential reasons include numbness in the nerves associated with digestion. This condition is called neuropathy.
Another reason could be a commonly used sweetener by diabetics called sorbitol, which is a potent laxative. Diarrhea in diabetics could also be attributed to complications the disease might cause in the enteric nervous system, which regulates functions in the gastrointestinal system.
Acute Causes of Diarrhea after Eating (Postprandial Diarrhea)
Acute postprandial diarrhea is defined as watery stools following meals for less than 14 days. It can usually be treated with medication or left for the body to heal itself. It can be the result of a number of causes.
Food poisoning: The good news is that your body is very good at noticing when it has eaten something it shouldn’t. The bad news is that this can result in diarrhea as shortly as 20 minutes after eating the contaminated food.
Viral infection: Various viruses from Norwalk to viral hepatitis can make your intestines or stomach extra sensitive and more likely to jump the gun on the defecation reflex.
Lactose intolerance: Lactose is a sugar that normally gets broken down by lactase, a digestive enzyme. Those with lactose intolerance don’t have enough lactase, which causes lactose to be carried to the colon where it can trigger an early bowel movement.
Fructose intolerance: Similar to lactose intolerance, some people are unable to properly digest fructose. This intolerance can also translate to other sugars and sweeteners like sorbitol. An elimination diet would help determine sensitivities to these substances.
Parasites: Certain foodborne parasites, such as tapeworms, can trigger acute diarrhea upon first being ingested. If a parasite manages to take up residence, you may continue to experience sporadic diarrhea later on.
Toddler’s diarrhea: This is a bout of diarrhea that can sometimes become chronic. It’s triggered by giving too much fruit juice to an infant, since the sugars drag excess water into the bowel.
Magnesium: Overdose-levels of magnesium can make you more prone to bouts of diarrhea after eating. It’s almost impossible to reach the triggering amounts without taking a magnesium supplement, which people some do since it can be used as a laxative.
Antibiotics: Antibiotics can lead to diarrhea by wiping out the beneficial gut bacteria responsible for breaking down the food you eat. Some people may also have an acute reaction lasting for the course of the cycle, which will subside once it’s completed.
Causes of Bowel Movement after Eating a Meal
Diarrhea after Eating Fatty Foods
Some people find that they get diarrhea only after eating certain foods. If this is the case, it may help narrow down the underlying cause. Fat is one of the bulkier components in stool and is consequently able to provoke a sensitive gut more easily than other nutrients. Diarrhea after eating fatty foods suggests an irritable bowel disorder or a digestive disorder that affects your ability to process fats.
It should be noted that there is a difference between having difficulty metabolizing fats and having diarrhea after eating a greasy meal like pizza or a burger and fries.
If you have a digestive condition limiting your ability to metabolize fats, you would have pain or diarrhea after eating foods like almonds, avocado, olive oil, and other sources of healthy fats.
However, if you regularly eat processed and fatty foods and have digestive issues, it may simply be a matter of making some healthier decisions.
Greasy processed foods can lead to gastrointestinal issues by causing inflammation and creating a homogenous and unhealthy microbiome. In order to fix this problem, try limiting the amount of greasy processed food in your diet and including more nutrient-rich foods that can stimulate a healthier population of bacteria.
These include a mixture of leafy greens, fruit, fermented foods like yogurt and kefir, as well as whole grains. These items possess fibrous, prebiotic, and probiotic compounds that can improve your population of gut bacteria.
Diarrhea after Eating a Salad
Although uncommon, you may find yourself experiencing bouts of diarrhea after eating a salad or lettuce (you may even find signs of lettuce when looking at the stool itself). Lettuce and similar plants are largely insoluble fiber, which means that they will pass through without getting digested.
If your diet consists primarily of insoluble fiber, which can happen in cases like the Paleo diet, salad can become capable of triggering diarrhea. You may also be eating a lot of salad that hasn’t been washed properly or is otherwise contaminated, so keep that possibility in mind too.
Diarrhea after Eating Out
If you are getting diarrhea after eating out but not from any singular restaurant, you may have a dietary intolerance or sensitivity. Consider the differences in what you eat at home versus what you eat out. Are there any ingredients unique to the restaurant food?
While you should always get a proper diagnosis for dietary conditions, these questions can help you and your doctor figure out what to check for.
Diarrhea after Eating Eggs
If you get diarrhea after eating eggs, then the culprit is probably salmonella. Eating eggs raw might have looked cool (or gross) in Rocky, but cooking them is a better idea. But if the eggs are spoiled or contaminated, there’s a good chance diarrhea will follow. Another possibility is that that you’re allergic to eggs, so it’s worth getting tested to be certain.
Recognizing the Symptoms of Diarrhea after Eating (Postprandial Diarrhea)
Diarrhea can be accompanied by various other symptoms. Paying attention to what accompanies your bowel issues can help inform your doctor and result in a more accurate diagnosis. Some of the symptoms to keep in mind are:
- If you get yellow diarrhea after eating, it could be a sign that something is up with your gallbladder.
- Black feces means you’ve digested some blood, so there may bleeding somewhere in the upper gastrointestinal tract.
- Conversely, bright red blood indicates bleeding along the lower gastrointestinal tract.
- A fever indicates that there’s an infection.
- Vomiting also indicates the presence of an infection.
- Bloating can imply bacterial causes, IBS, or other digestive disorders.
- Abdominal cramps or pain suggest illness or IBS.
- Dry mouth or skin, excessive thirst, weakness, dizziness, and minimal urine or dark urine are signs of dehydration and should be treated immediately.
How to Treat Diarrhea after Eating
There are only a small handful of options that can be used to treat in-progress bouts of diarrhea.
The most important thing to remember when treating diarrhea is to stay hydrated. As mentioned earlier, diarrhea is watery because you defecate before enough fluid has been reabsorbed by the body. This means that dehydration is a very real threat when suffering diarrhea.
You should have at least one cup of liquid after every diarrheic bowel movement. This can include water, clear fruit juice, flat ginger ale, soup broth, or other drinks. Avoid alcohol since it can make things worse.
2. Medication or Infection
Medical options are going to depend on the cause. If you have food poisoning or an infection, your doctor can prescribe antibiotics, antivirals, or antiparasitics to treat the underlying culprit.
Since these drugs are type-specific, it’s important to make sure you know what needs to be treated before taking one blindly if you want to avoid taking a drug that turns out to be ineffective.
3. Anti-Diarrhea Treatment
Some over-the-counter options for diarrhea exist, such as “Pepto-Bismol,” but they may not be appropriate in cases of infection. Remember that the diarrhea you get from something like food poisoning is your body trying to expel the pathogen and this process should be allowed to happen when possible.
Since certain infections or other medical conditions can be made worse by using diarrhea medicines, you should double-check with your doctor before using one.
4. Gentle Foods
Your bowels may be sensitive following a bout of diarrhea, especially if it was brought on by food poisoning. Try easing your gut back to a normal diet by starting off with semi-solid or easily digestible foods including toast, soda crackers, or soup.
Preventing Diarrhea after Eating (Lifestyle Changes for Diarrhea after Eating)
In contrast to treating active diarrhea, prevention is a much simpler and easier task since it primarily involves avoiding possible triggers and making sure your food is washed properly. The individual measures that need to be taken will vary depending on the underlying cause, so not all of these tips will be applicable to every person.
- Wash fruits and vegetables thoroughly before eating.
- Cook meat to a proper temperature.
- Make dietary adjustments to avoid triggering nutrient sensitivities.
- Use added enzymes (lactase, etc.) before eating something with a triggering component.
- Eat several small meals throughout the day instead of the standard three large ones.
- Eat probiotic foods to help improve your gut flora.
- Avoid known aggravators such as fatty, spicy, or highly seasoned foods during the post-diarrhea recovery period to avoid relapse.
- Sometimes food contamination occurs in the refrigerator, which can lead to diarrhea. Avoid storing different raw foods together, seal leftovers, and eat food in a timely fashion.
When to Contact a Doctor
It’s highly advisable to contact your doctor or seek medical attention if you start to experience any of the following:
- Diarrhea persists for more than three weeks on-and-off, or constantly happens for three days.
- Diarrhea is accompanied by a fever, especially one higher than 102 degrees Fahrenheit.
- Diarrhea is accompanied by severe abdominal or rectal pain.
- Diarrhea is bloody, black, or gray.
- You begin to show signs of dehydration (excessive thirst, dizziness, weakness, etc.).
Additionally, special care needs to be taken when monitoring an infant who suffers from diarrhea. Infants are more susceptible to dehydration from diarrhea and medical attention should be sought if they start to show the following:
- The infant hasn’t wet their diaper in over three hours.
- The baby cries without tears.
- The infant has a sunken appearance around the eyes, cheeks, or abdomen.
- The skin is not immediately smooth after a brief pinch.
- The infant is unusually drowsy, sleepy, irritable, fussy, or is unresponsive.
Ditch Diarrhea after Meals by Improving Digestion
If you’re experiencing diarrhea after meals, it could be caused by either chronic or acute conditions. Central to them, however, is digestion. There are ways to improve digestion and avoid foods that trigger diarrhea, so identifying the source of the troubles and exploring your options are highly recommended.
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