Does Diarrhea Cause Weight Loss? Tips To Relieve Diarrhea [UK] 2023

Sevginur Akdas

Updated on - Written by
Medically reviewed by Kathy Shattler, MS, RDN

does diarrhea cause weight loss

Diarrhea is a digestive problem that progresses with changes in the form and amount of stool and can cause some complications. 

Diarrhea can cause serious health outcomes, especially in young children. However, diarrhea can also be seen in adults and can significantly reduce the quality of life.

One of its important effects is that it can cause weight loss due to changes in digestion and absorption in the intestines. The reason why some diseases cause continuous weight loss in the patient may be diarrhea as one of the complications of that disease.

Can Diarrhea Cause Weight Loss?

What Is Diarrhea? 

Diarrhea is a loose or watery stool with increased stool frequency. It can occur with abdominal pain, cramping, gas, or an uncomfortable feeling in general. If it lasts less than seven days, it is called acute diarrhea. Still, if you can’t get back to a normal defecation routine after seven days, it means you have persistent or chronic diarrhea, which is a more severe condition for your health.

In the United States, acute diarrhea[1] is a common reason for hospital visits. It means an important health cost for people and the government. 

Diarrhea, whether acute or chronic, can cause you to lose weight. If you have acute diarrhea, your weight loss may not be critical. It can be only due to the emptiness of your bowels or water weight that you lose with diarrhea, not real body fat or muscle loss. But persistent diarrhea generally causes extreme water weight loss with accompanying muscle tissue wasting and body fat loss. 

What Are The Reasons?

We can classify diarrhea[2] according to its reason or type. For example, inflammation is an important factor in examining diarrhea, and it strictly changes all clinical outcomes. Inflammatory diarrheas, such as Crohn’s disease, irritable bowel syndrome, or dysentery, can be very dangerous, and blood or mucus fluid accompanies stool. Hospitalization may be needed in this situation to deal with unexpected weight loss, electrolyte imbalances, and dehydration. 

Diarrhea without inflammation depends on increased water secretion into the bowel, or your bowels can not reabsorb water enough. Foodborne diarrheas are generally in this group. 


The most common pathogens[1] causing bacterial infections leading to diarrhea are Salmonella, Shigella, Clostridiumdifficile, Campylobacter, and Escherichia coli. Besides bloody stools, these patients also have severe abdominal pain or high fever and up to 10-15 watery stools per day, potentially causing severe dehydration. 

Diseases And Physiological Conditions

Some diseases[3] may cause severe & chronic diarrhea,[4] such as inflammatory bowel disease, celiac disease, cancers in the digestive tract, etc.

On the other hand, when your digestive tract loses water absorption function or there is too much secretion into the bowel, diarrhea occurs. This type of diarrhea is classified as non-inflammatory diarrhea.

You may lack specific enzymes or functions that your digestive tract normally should have. A good example is lactose or gluten intolerance. If you cannot tolerate lactose from dairy products, the indigestion of this milk sugar may make you feel uncomfortable and have bloating or even diarrhea. Gluten triggers an immune response that triggers malabsorption and diarrhea.

Dietary And Environmental Factors

Diarrhea can be included in foodborne illnesses[5] too. Due to negligence in the proper processing, storage, and cooking of foods, foods may spoil and cause infections that cause diarrhea.

Another cause[6] of diarrhea is changing microbiota profile. When you eat radically different foods or travel entirely to another place, your intestinal bacteria profile starts to change. Sometimes these situations affect bowel habits and bowel movement leading to constipation or diarrhea. There is a term called Traveler’s Diarrhea for this type of reaction. 

Stimulating chemicals such as alcohol or caffeine can also increase bowel movement. When the food transit speeds up, your bowel can not have enough time to absorb water, and the result is a watery stool. 

Psychosocial stress factors[7] may also change your bowel habits. Some people may have constipation, and up to 179 million people have some form of diarrhea under stressful conditions as it is well-known that the bowel is a marker of mental health signals.

Several medications[7] or supplements may also affect bowel movement and secretory function. Or if you use antibiotics, it is an expected result to change your gut microbiota which is closely related to the regulation of defecation habits.

How Does Diarrhea Cause Weight Loss?

To better understand, it is helpful first to summarize brief intestinal physiology. When we consume food, it reaches the intestine after digestion in the stomach. In the intestinal area, absorption begins while digestion also continues. 

Specialized cells in the intestinal wall uptake the building blocks of carbohydrates, proteins, and fats into the cell through special regions on the cellular lining of the gut wall. Similarly, the absorption of vitamins and minerals takes place here. However, a significant amount of water reaches the intestine due to the foods and beverages we consume. 

Further, the digestive system itself produces many liquid secretions, which in turn reach the intestine. There are nearly nine liters of water per day entering the intestine.[8] And only 0.1-0.2 liters of it is excreted in the stool. This is the best proof that the intestine is a very good reabsorption organ.

However, for the reasons we have explained above, disorders may occur in the intestinal or structural reabsorption mechanisms. Intestinal tissue involvement due to diseases does not allow the intestine to perform its function. Or the bowel movements may be too sped up to fulfill the absorption process. The body cannot benefit enough from the nutrients it receives through the diet, and a calorie deficit may occur while these nutrients are removed from the body with diarrhea.

However, this problem can be encountered in severe intestinal disorders. When we look at diarrhea in general, there is significant water loss. In mild diarrhea and not caused by a structural problem, weight loss on the scales can usually signify fluid loss in the body. Resulting dehydration may cause a drop in blood pressure, although it has been known that the stress of a dysfunctional gastrointestinal tract[9] leading to diarrhea may cause high blood pressure.

Therefore, the first thing in treating diarrhea is replacing the lost water and minerals.

Diagnosing The Issue

Several tests can be used to diagnose[3] diarrhea doctors.

Stool Tests: A stool sample is examined for infection. Also, the form or content of stool gives an idea about the disease.

Colonoscopy Or Sigmoidoscopy: With this procedure, your bowel is examined for a structural problem, fistula, or inflammatory tissue causing diarrhea. A long, thin tube with a camera attached is inserted through the anus, and doctors examine the intestine via this camera. Image and tissue samples can be taken during this procedure. In sigmoidoscopy, only the lower part of the large intestine is examined.

Non-invasive Imaging Methods: Ultrasound, X-rays, or other imaging tests may be used.

Blood Tests: Blood tests can also be used to examine the presence of an inflammatory response, whether there is blood loss in the stool, vitamin-mineral levels, and biomarkers used for the differential diagnosis of some diseases.

How To Deal With Weight Loss Caused By Diarrhea

Water Intake And Rehydration

does diarrhea cause weight loss

The first rule is to drink water to deal with diarrhea. It would be best if you protect yourself from dehydration. Also, you may lose electrolytes such as sodium, potassium, and chloride during diarrhea. Therefore it is beneficial to replace them with an electrolyte replacement solution. You may also be asked to follow a low-fiber diet since fiber stimulates the bowel and may worsen diarrhea. 

If you are hospitalized, your doctor may give you a rehydration solution[10] to prevent dehydration.

But suppose you can’t go to the hospital. In that case, you can drink Oral Rehydration Salt, which is a product to treat diarrhea and dehydration. If you can’t buy these salts, you can prepare a rehydration solution at home, as recommended in this guide.[11]

This is a very effective treatment to prevent unwanted health outcomes of diarrhea and dehydration, especially for low-income countries because diarrhea is the leading child death in low-income countries. This oral rehydration solution can also be used in adults with severe diarrhea. 

Preparation Of Oral Rehydration Solution

  • Six teaspoons of granulated sugar
  • One liter of clean water
  • 1/2 teaspoon of table salt

You need to use clean water, or you can be sure by boiling the water that you use, then adding sugar and salt. You may wonder why we add sugar. Unnecessary and excessive sugar causes diarrhea on its own. Still, the reason sugar is included is that you need some glucose to reach the osmolarity that your body needs to rehydrate. Also, our cells uptake sodium ions together with glucose. Therefore, not an excessive but a specific amount of sugar helps in rehydration.

You may consider consuming banana or orange juice to get some potassium, plus it can give a good taste. 

Foods To Help With Diarrhea

does diarrhea cause weight loss

Foods such as:

  • bananas.
  • plain white rice.
  • oatmeal or rice porridge.
  • bread or toast.
  • boiled potatoes.
  • applesauce.

These foods can help you to reabsorb water in the intestine because they have soluble fiber, which regulates the form of the stool. But you may not prefer fibery foods high in insoluble fibers, such as leafy greens or starchy veggies, because insoluble fibers may worsen the situation.

Also, you can prefer a small amount of food in each meal rather than a large amount of food consumption at once to help your digestive system work. After your digestive system gets back to normal, it is beneficial for you to replace your calorie deficit with a healthy, well-balanced diet with an adequate intake of macro- and micronutrients

You may consider probiotics use, but you need to ask your doctor first if probiotics are suitable for your condition. Some strains of probiotics are more beneficial than others in treating digestive disorders such as diarrhea. 

Things To Avoid

Excessive Sugar

does diarrhea cause weight loss

Excess sugar does not allow water to be absorbed due to the osmotic density it will create in the intestine. For this reason, avoiding drinks containing too much sugar and ready-made foods is beneficial.

Fats And Fatty Meats

does diarrhea cause weight loss

Fats and meats are hard to digest. When there is a problem in the digestive system, these foods can complicate this process. You should eliminate fatty and processed foods from your diet in chronic or acute diarrheal states.

Dairy Products

does diarrhea cause weight loss

Many adults can have lactose intolerance. Therefore you should be careful about consuming dairy products if you have lactose intolerance or consider taking lactase enzyme Also, lactase, the enzyme that we produce to digest lactose in milk, is the enzyme whose production can be affected by some digestive problems, such as diarrhea. It means you may develop lactose intolerance due to your digestive disorder, even if you don’t have any lactose intolerance under normal situations.

Caffeine And Spicy Foods

does diarrhea cause weight loss

In the case of diarrhea, there is intestine irritation. Caffeine and some spices stimulate the intestines. This can aggravate diarrhea.

Caffeine, in particular, can accelerate bowel movements as it stimulates contraction in muscle cells.

Too Much Exercise

does diarrhea cause weight loss

You may be unable to exert enough effort for exercise due to fatigue from diarrhea. Lactose intolerance may be increased due to regular exercise.  In addition, with training, your water loss will increase, and your chances of dehydration from resulting diarrhea will increase. Increased physical activity also increases your energy expenditure and deepens your calorie deficit. 

Keto Diarrhea

does diarrhea cause weight loss

The keto diet may also cause diarrhea due to a low fiber intake, too many medium chain triglycerides, and a decline in digestive enzymes that all occur while following this type of diet. If you are dealing with bouts of diarrhea, this diet may not be for you.


Diarrhea is a digestive problem every adult can encounter daily and is usually quickly resolved. However, suppose you have diarrhea due to a pathological reason. You should pay attention to this issue and talk to your doctor and registered dietitian. Because if left untreated, diarrhea can cause unhealthy weight loss and poor absorption of nutrients.

+ 11 sources

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Sevginur Akdas

Written by:

Sevginur Akdas, RD

Medically reviewed by:

Kathy Shattler

Sevginur Akdas is a researcher, medical writer, and clinical dietitian, who is currently pursuing her Ph.D. in metabolism, chronic diseases, and clinical nutrition fields. She has many scientific articles, meta-analyses, systematic reviews, and book chapters on nutrition, chronic diseases, dietary supplements, maternal and child nutrition, molecular nutrition & functional foods topics as a part of a research team currently. Besides her academic background, she is also a professional health&medical writer since 2017.

Medically reviewed by:

Kathy Shattler

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