Does Diarrhea Cause Weight Loss?

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Diarrhea is a common health complaint. Even healthy adults and children may experience a few bouts of diarrhea each year. In the majority of cases, the symptoms are acute (short-term) and will clear up in a few days.

Diarrhea that continues longer than three days is a reason to consult your healthcare provider as it may be a symptom of a more serious health condition, such as a gastrointestinal infection (like from a bacteria called Clostridioides difficile or C. diff.), celiac diseaseirritable bowel syndrome (IBS), or inflammatory bowel disease (IBD).

Persistent diarrhea lasting more than four days or chronic diarrhea lasting more than four weeks may lead to other complications, including dehydration and unintended weight loss. It's important to get a diagnosis so that the underlying cause of diarrhea can be addressed.

A person standing on a scale

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This article discusses the potential causes of chronic diarrhea and how it can lead to unintended weight loss. It also explains how the condition is diagnosed and treated.

Diarrhea and Weight Loss

Diarrhea refers to stools that are loose and watery. Loose stools may be accompanied by changes in bowel movements, including increased frequency and/or urgency or fecal incontinence. Over time, increased frequency of stool may cause weight loss.

Diarrhea can be either acute, persistent, or chronic. Acute diarrhea lasts less than two weeks and is one of the most common illnesses in the United States.

Diarrhea that lasts between two to four weeks is considered persistent. Diarrhea that continues for longer than four weeks is characterized as chronic. Chronic diarrhea affects an estimated 5% of the population at any given time.

How Digestive Problems Cause Weight Loss

When you have chronic diarrhea over days or weeks, you can lose a lot of body fluid. This loss of body fluid may show up on the scale as weight loss.

Diarrhea can also be accompanied by other symptoms, such as nausea or loss of appetite, that also make it hard to keep food and liquids down. This reduces your calorie intake, which can also contribute to weight loss.

Depending on how long diarrhea lasts and the severity of symptoms, the weight loss can be significant. However, any weight lost during a bout of diarrhea is mostly water weight and will likely return once your bowel movements and appetite are back to normal.

Related Symptoms

Chronic diarrhea may be accompanied by other symptoms that can indicate an underlying health condition. Associated symptoms may include:

Causes of Persistent or Chronic Diarrhea

Diarrhea can have many causes. Most cases of acute diarrhea are caused by an infection. The infection may be bacterial, viral, or parasitic. Often, this type of diarrhea will resolve on its own within a few days.

In some cases, acute diarrhea can result from changes in diet, such as consuming too much artificial sweetener or alcohol, or from other lifestyle factors, including stress.

Persistent or chronic diarrhea may be caused by a number of underlying health conditions or other factors. These include:

  • Medications: Diarrhea is a side effect of certain drugs, including antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), and chemotherapy.
  • C. diff. infection: This type of infection often develops during or after a course of antibiotics, or it may be caught in a hospital or nursing home.
  • Inflammatory bowel disease: IBD includes Crohn's and ulcerative colitis, chronic conditions that cause inflammation of the gut and present with diarrhea.
  • Irritable bowel syndrome: IBS is a condition where the muscles that move waste through the intestines are highly sensitive to certain triggers.
  • Celiac disease: This is an autoimmune condition in which the immune system overreacts to the wheat protein gluten and attacks the lining of the small intestine.
  • Food allergy or intolerance: Food intolerance is caused by a lack of the enzymes needed to digest a specific food. Lactose intolerance, the inability to digest the sugars in milk, is the most common, but it's possible to be intolerant of other foods as well.
  • Diverticulitis: This condition causes inflammation of the diverticula (pockets of tissue in the large intestine), leading to diarrhea that is often accompanied by abdominal pain.

Diagnosing the Issue

If you have diarrhea that continues longer than a couple of weeks and you're losing weight unintentionally, it's important to make an appointment with your healthcare provider. To make a diagnosis, your healthcare provider will take a health history, do a physical exam, and more.

Health History

In taking a complete health history, your doctor will ask you a number of questions. These may include:

  • Details about how long you have been experiencing diarrhea
  • How frequently you have diarrhea
  • How much stool you pass
  • If you have other symptoms that accompany the diarrhea
  • Details about what the stool looks like
  • What foods you eat and what beverages you consume
  • If you are taking any medications or have in the past
  • If you have traveled to a developing country
  • If you have interacted with a sick person

Your healthcare provider may also ask about your family history and whether anyone in your immediate family has conditions such as:

  • Ulcerative colitis
  • Crohn's disease
  • Irritable bowel syndrome
  • Celiac disease
  • Lactose intolerance

Diet and Lifestyle

If your healthcare provider believes you may have a food intolerance or an allergy, they may ask you to make some changes to your diet to see if it helps improve your symptoms.

Changes may include spending about two weeks avoiding foods that contain common food allergens, such as wheat, dairy, eggs, nuts, corn, and soy.

You'll be asked to keep a food diary, noting your symptoms as you slowly re-introduce certain food. This can help doctors determine which foods might be triggering your symptoms.

Laboratory tests

A number of tests may be used to determine the cause of diarrhea. These include:

  • Stool tests: This usually involves testing a sample of stool for the presence of an infection.
  • Colonoscopy: During this procedure, a long, thin tube with a camera attached is inserted through the anus and threaded up the intestine. It is used to take images and a tissue sample. This test can show whether tissue is inflamed, if there are sores or ulcers, if there are abnormal growths, or if there is evidence of bleeding.
  • Sigmoidoscopy: Similar to a colonoscopy, this test only sees the inside part of the lower part of the large intestine. Tissue samples can also be taken.
  • Imaging studies: An ultrasound, X-rays, or other imaging tests may be used to look at organs and see if there are abnormalities.
  • Blood tests: Bloodwork may be used to test for the presence of an infection, evidence of bleeding, thyroid disease, celiac disease, and low levels of vitamins, which could indicate poor nutrient absorption in the gut.

Treating Diarrhea and Weight Loss

Treating diarrhea and associated weight loss will depend upon the underlying cause. If diarrhea is found to be due to a virus, bacteria, or parasite, your healthcare provider may prescribe a medication to treat the infection.

If the cause of diarrhea is celiac disease or a food allergy or intolerance, you may be advised to start a special diet. Diet changes are also often recommended to manage IBS and IBD.

Prescription medications may also be required to treat the underlying causes of chronic diarrhea. This includes medications for conditions like:

  • Crohn's disease
  • IBS
  • Ulcerative colitis

In some cases, your healthcare provider may also recommend taking probiotics or eating more probiotic-rich foods and drinks, like yogurt, kefir, and kombucha. These foods and supplements contain good bacteria that can help bolster the population of similar healthy bacteria naturally found in the digestive tract.


Chronic diarrhea is diarrhea that persists longer than four weeks. This can result in weight loss and be accompanied by a variety of other symptoms, including fatigue, nausea, and abdominal pain.

Chronic diarrhea can be caused by an infection, stress, some medications, or underlying health conditions like IBS, IBD, or celiac disease. Identifying the cause of diarrhea will help determine the best treatment for diarrhea and associated weight loss.

A Word From Verywell

Experiencing diarrhea that continues for weeks can be painful, embarrassing, and disruptive to your everyday life. It can also lead to additional complications, like fatigue, nutrient deficiencies, and unintended weight loss.

If you have diarrhea that hasn't resolved on its own, or you are losing weight without trying to, consider making an appointment with your healthcare provider. They will be able to help you identify the cause of your diarrhea and weight loss, and offer options to treat it.

Frequently Asked Questions

  • Does prolonged diarrhea cause nutrient deficiencies?

    Chronic diarrhea that lasts longer than four weeks can lead to malnutrition. For this reason, it's important to speak with your healthcare provider if diarrhea persists.

  • When should you worry about unexplained weight loss?

    Losing more than 10 pounds (4.5 kilograms), or a loss of 5% of your normal body weight, over a period of six to 12 months without intentionally trying to lose weight is considered unexplained weight loss and merits seeking medical attention. You should also contact your healthcare provider if your weight has dropped to a level below that which is considered healthy for your age and height.

  • Can anxiety or chronic stress cause weight loss?

    Weight loss can be caused by many factors, including stress, anxiety, and depression. Other causes include chronic illness, chronic infection, drug abuse, and cancer.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  7. National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for Diarrhea
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