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Does Diarrhea Cause Weight Loss? 5 Important Causes of Chronic Diarrhea and Weight Loss

We all have faced diarrhea at some point in our lives. Needless to say, it isn’t a pleasant experience. Diarrhea causes your stool to become loose and watery, and also increases the frequency of bowel movements, meaning you have to go to the bathroom multiple times a day, and in severe cases multiple times an hour. 

Diarrhea makes us feel weak and fatigued as the body loses a lot of fluid volume in a short period of time. But prolonged diarrhea can also cause significant weight loss. But how does diarrhea cause weight loss? Is it a viable way to lose some weight? Or is it something you should be worried about?

In this article, I’ll be talking about the effects diarrhea has on the body and how it may cause weight loss. So let’s get started.

Chronic diarrhea is caused by underlying clinical conditions. These may include malabsorption syndrome, ulcerative colitis, Chron’s disease, autoimmune conditions or immunocompromised states, intestinal polyps, etc.

Table of Content

How Does Diarrhea Cause Weight Loss?

The weight loss caused by diarrhea depends on the kind of diarrhea you’re affected by. It can broadly be divided into two types: acute diarrhea and chronic or persistent diarrhea. 


These two types of diarrhea have different mechanisms for weight loss. In the case of acute diarrhea, it’s mainly caused by loss of fluid volume, and in chronic diarrhea, it’s caused by more serious underlying complications.

Acute Diarrhea:

In the case of simple or acute diarrhea, the causes are usually food poisoning, traveler’s diarrhea, stomach flu, indigestion, etc. 

Food poisoning or traveler’s diarrhea is caused by harmful bacteria like staphylococcus, salmonella, or E. coli. These bacteria enter the body through contaminated food or water and then secrete exotoxins that irritate and damage the bowel, causing loose stool and diarrhea. Similarly, one can get diarrhea by viral infections, most commonly by rotavirus. 

Diarrhea caused by bacterial infections can be treated easily using antibiotics and usually get better within 2-3 days. In the case of stomach flu, it gets better by itself in a few days without the need for medication.

Some drugs can also cause diarrhea, such as if you are taking Metformin for diabetes. Check out this article on how metformin can cause diarrhea to learn more.

Chronic Diarrhea:

Chronic diarrhea is caused by underlying clinical conditions. These may include malabsorption syndrome, ulcerative colitis, Chron’s disease, autoimmune conditions or immunocompromised states, intestinal polyps, etc. Diarrhea in this case is a symptom of the causative disease and is treated by treating the underlying cause.


In conditions like malabsorption syndrome, the body suffers from deficiencies of some digestive enzymes, causing food to remain undigested and unabsorbed. This over a prolonged period may cause weight loss due to malnutrition. Other conditions may cause injury or damage to the intestinal wall, preventing the absorption of nutrients from food and causing weight loss.

Most cases of diarrhea-associated weight loss are a result of chronic diarrhea and its underlying causes. So, it’s best to get a clearer understanding of what causes chronic diarrhea and how it causes weight loss. 

Chronic Diarrhea and Weight Loss:

When it comes to weight loss, chronic diarrhea plays a more significant role than acute diarrhea. So it’s important to understand what causes chronic diarrhea and how it affects your weight.

Chronic diarrhea has a broad list of possible causes. These can mainly be categorized into two groups: inflammatory causes and secretory causes. Inflammatory causes include chronic inflammatory conditions of the gut like irritable bowel syndrome and inflammatory bowel disease. On the other hand, secretory causes may be a result of chronic infections by bacteria, parasites, etc.

Now, let’s take a look at the most common causes of chronic diarrhea:

Irritable Bowel Syndrome:

Irritable Bowel Syndrome or IBS is a common bowel disorder that can cause persistent diarrhea or constipation. It is a very common problem affecting 15% of adults in the United States, women being twice more likely to be affected than men. 

The exact cause of IBS is not yet fully understood. But it is believed that it’s caused by imbalances in the normal microbial flora of the gut, muscle contractions, problems with the enteric nervous system, etc. IBS can cause symptoms like gas, bloating, diarrhea, iron deficiency anemia, unexplained vomiting, and weight loss. 

Inflammatory Bowel Disease:

Inflammatory bowel disease or IBD denotes a group of diseases that cause severe inflammation of the gut. IBD includes diseases like Chron’s disease and Ulcerative colitis. These diseases are immune-mediated, where the body’s immune system reacts against its own naturally occurring substances or the normal microbiota of the gastrointestinal tract. The exact etiology of IBD is still not known.

Chron’s disease may affect the entire digestive tract from the small intestines to the rectum. It also affects the entire thickness of the intestine, which may cause issues like intestinal obstruction. Chron’s disease can usually be treated by surgery.

Ulcerative colitis occurs only in the large intestines and affects only the mucosal and submucosal layers of the colon. It is usually accompanied by inflammation in other organs like the skin, eyes, and joints. It can also cause rectal bleeding and blood clots.

IBD impairs the normal function of the gut and prevents the absorption of nutrients from food like iron and vitamin B12. This causes problems like malnutrition, iron deficiency anemia, and weight loss.

Lactose Intolerance:

Lactose intolerance is a very common malabsorption disorder. Around 68% of people across the globe have some degree of lactose intolerance. It is the condition when the body has a functional deficiency of lactase, an enzyme necessary to break down lactose, a disaccharide sugar present in milk and dairy products.

If you take milk or any milk-based food and are lactose intolerant, your body can’t digest the lactose which is the main component of dairy. As a result, the undigested lactose creates an osmotic imbalance in the gut causing bloating, flatulence, abdominal pain, cramps, painless watery diarrhea, and weight loss. 

If you are experiencing sudden weight loss along with diarrhea, it may indicate some more serious underlying health problems and a severe decline in overall health. Sudden weight loss is a major red flag for many deadly diseases like cancer. In such cases, abdominal pain, digestive problems, and diarrhea may be secondary symptoms.

Celiac Disease:

Celiac disease or gluten intolerance is an immune-mediated disorder where the body produces an immune response against a specific protein found in some grains called gluten. Celiac disease is prevalent in about 1% of the world’s population, and the number is rising. 

In celiac disease, the immune response produced against gluten creates a complex that damages the lining of the intestines. Over time, this may cause severe damage to the intestinal lining, causing long-term digestive lining, malabsorption, abdominal pain, diarrhea, and weight loss. 


If you have gluten intolerance and are struggling to find a good diet plan, check out this article for great tips on making a gluten-free diet plan.

Chronic Infections:

Another possible cause of chronic diarrhea is infection by organisms like bacteria or, parasites. Bacterial infections from E. coli, Salmonella, Shigella, V. cholerae, C. difficile, etc. if left untreated can produce gastroenteritis, chronic bloody diarrhea, and bacillary dysentery. Again parasitic protozoa like E. histolytica, Giardia, Cryptosporidium, Cyclospora, etc. can cause amoebic dysentery.

Chronic infections cause injury and ulcerations in the intestinal lumen. This causes impaired absorption of nutrients, leading to malnutrition and weight loss.

Your physician will always suspect an infectious cause for diarrhea. This is why it is common practice to prescribe antibiotics in case of acute diarrhea and also to suggest stool examinations for evidence of parasites. 

Causes of Unexplained Weight Loss

If you are experiencing sudden weight loss along with diarrhea, it may indicate some more serious underlying health problems and a severe decline in overall health. Sudden weight loss is a major red flag for many deadly diseases like cancer. In such cases, abdominal pain, digestive problems, and diarrhea may be secondary symptoms. So it is important you know which diseases cause sudden and unexpected weight loss. 

Some conditions that cause sudden weight loss are:

  • Cancer: The symptoms of cancer can vary greatly depending on the type and the area affected. But the most common symptoms of cancer are fatigue, changes in bowel habits, unexplained lumps or swelling, and unexplained weight loss.
  • Amyloidosis: Amyloidosis is a rare disease where an abnormal protein called amyloid is produced in the body and accumulates in the organs causing impairment of normal function. Symptoms of amyloidosis include edema of the ankle and lower limbs, severe fatigue, shortness of breath, sudden weight loss, and abnormal enlargement of the tongue.
  • HIV infection: HIV is one of the most deadly viruses known to man. It causes AIDS or Acquired Immune Deficiency Syndrome, where HIV destroys the body’s immune system. Symptoms of HIV infection include fever, persistent cough and diarrhea, rashes, delayed healing, and significant weight loss.
  • Hyperthyroidism: Hyperthyroidism is a condition in which the thyroid gland produces too much thyroxine hormone, which is a potent metabolic accelerant. Hyperthyroidism can be caused by thyroiditis, autoimmune conditions like Grave’s disease, or tumors of the thyroid gland. Too much thyroxine causes an uncontrolled increase in metabolism, resulting in arrhythmias of the heart, tremors, anxiety and irritability, and sudden weight loss.
  • COPD: COPD of Chronic Obstructive Pulmonary Disease, is a chronic inflammatory disease of the lungs obstructing airflow and shortness of breath. COPD is caused by long-term exposure to irritant particulates like cigarette smoking, working in mines and construction sites, exposure to silica, asbestos, etc. Symptoms of COPD are difficulty in breathing, wheezing, chronic cough with sputum, chest tightness, lack of energy, and unexplained weight loss.
  • Depression: Depression and other associated mental health issues are one of the biggest causes of unexplained weight loss. Along with the obvious mental symptoms, depression may trigger physical responses like loss of appetite, lethargy, sleep disturbances, and weight loss.

If you’re looking for safe and sustainable methods of weight loss, check out this article on how to lose 10 pounds in a month.

Diagnosis and Treatment

If you are facing diarrhea lasting for more than two days, you must go see a doctor as soon as possible. Your doctor will ask about your medical history to diagnose the kind of diarrhea and also to suggest appropriate tests and formulate a treatment plan. 

You should be completely honest with your doctor and give a detailed account of your bowel movements, food habits, the nature of the stool, any medication you’re taking, or any recent traveling history. Your doctor may also ask about family history for hereditary diseases. 

After this, the doctor will recommend some tests. These are usually a battery of biochemical lab tests to detect infections or other common causes of diarrhea. If necessary the doctor may also suggest further tests like a sigmoidoscopy, colonoscopy, or imaging tests like X-ray and ultrasound.

The treatment of diarrhea will depend on the cause. If no exact cause can be determined, then your doctor will suggest over-the-counter antidiarrheal drugs like loperamide. In case of infections, antibiotics, and antiparasitic drugs might be prescribed. Your doctor may also give you advice regarding food intake, like avoiding spicy or irritant foods and alcohol. You can expect a full recovery within 2-3 days.


How much weight can you lose from diarrhea?

The average bowel movement evacuates around 1 pound of stool from the body. If you have diarrhea, you might lose a bit more due to the loss of body fluids. In the case of chronic diarrhea, you may experience more significant weight loss varying on the cause.

Does diarrhea cause weight loss in babies?

Diarrhea in infants can cause dehydration. This can lead to weight loss and other health issues.

Is diarrhea good for weight loss?

No, diarrhea is not an effective weight loss solution as it does not affect body fat, which is the main cause of being overweight.


So, does diarrhea cause weight loss? The answer is yes. Whether in the case of acute or chronic diarrhea, you can lose weight due to loss of body fluids, reduced intestinal absorption of nutrients, or some other process. 

In any case, diarrhea is not an ideal means of weight loss. Dehydration from acute diarrhea is very dangerous and may even be life-threatening if left untreated. So if you are facing weight loss from diarrhea, consult your doctor immediately.

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