If you’ve recently noticed weight loss and diarrhea, you’re likely concerned about what’s causing it. These two symptoms can occur together and often signal that something isn’t quite right with your digestive system. Whether it’s acute or chronic diarrhea, significant weight loss can sometimes accompany the condition due to the loss of fluids, poor nutrient absorption, or a decreased appetite. Understanding why you’re losing weight and dealing with diarrhea is essential for determining the best course of action for treatment.

At Genesis Lifestyle Medicine, we understand how challenging it can be to experience these symptoms. In this article, we’ll explore various reasons why you might be losing weight and dealing with diarrhea, as well as helpful tips for managing these symptoms.

Possible causes of weight loss and diarrhea

Acute infections

One of the most common causes of diarrhea and weight loss is an acute infection, which can be viral, bacterial, or parasitic in nature. Infections such as gastroenteritis, commonly referred to as the stomach flu, can result in watery diarrhea, nausea, and vomiting and lead to dehydration and reduced food intake, thereby contributing to weight loss. While these infections often resolve on their own, it’s essential to consult a healthcare provider for further investigation.

Chronic infections

In some cases, an infection can linger and lead to chronic diarrhea. An example is Clostridium difficile (C. diff) infection, which can occur after a course of antibiotics or in healthcare settings. This type of infection can cause persistent diarrhea and may result in significant fluid loss, leading to weight loss. If you have been experiencing diarrhea for more than two weeks and are losing weight, it’s crucial to seek medical attention to identify the underlying infection.

Inflammatory bowel disease (IBD)

Inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis cause inflammation in the intestines, leading to diarrhea, abdominal pain, and weight loss. These chronic conditions often require ongoing management through medications and, in some cases, dietary changes. If you have a history of gastrointestinal issues or if you notice blood in your stool, it’s important to speak with a healthcare provider to determine if IBD is the cause of your symptoms.

Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) is a condition in which the muscles of the intestines don’t function properly, leading to symptoms like diarrhea, constipation, bloating, and cramping. IBS can be triggered by certain foods, stress, or hormonal changes. While IBS doesn’t typically cause significant weight loss on its own, the ongoing diarrhea and associated discomfort can result in reduced food intake, leading to some weight loss. Managing IBS involves lifestyle changes, including diet adjustments, stress management, and sometimes medications.

Celiac disease

Celiac disease is an autoimmune condition where ingesting gluten (found in wheat, barley, and rye) damages the lining of the small intestine. This impairs the absorption of nutrients, leading to diarrhea, weight loss, and malnutrition. If you have unexplained diarrhea and weight loss, especially after eating foods containing gluten, it’s worth discussing celiac disease with your healthcare provider. A blood test and biopsy of the small intestine can confirm the diagnosis.

Food allergies or intolerances

Certain food allergies or intolerances can lead to gastrointestinal distress, including diarrhea and weight loss. Lactose intolerance, for example, occurs when your body lacks the enzyme needed to digest lactose, the sugar found in milk and dairy products. Similarly, food allergies can cause inflammation in the gut, leading to diarrhea and malabsorption of nutrients, which can result in weight loss. If you suspect food allergies or intolerances, an elimination diet guided by a healthcare provider can help pinpoint the problematic foods.

Malabsorption syndromes

Malabsorption syndromes occur when your body cannot absorb nutrients properly from the food you eat. Conditions like cystic fibrosis, chronic pancreatitis, or certain gastrointestinal surgeries can lead to malabsorption. This can cause diarrhea, bloating, and weight loss, as your body isn’t able to absorb essential nutrients. If you have a history of gastrointestinal issues or surgeries, it's important to speak with your healthcare provider about the possibility of malabsorption.

Tips to manage diarrhea and weight loss

Stay hydrated

Dehydration is a major concern when you’re dealing with diarrhea. The loss of fluids and electrolytes can quickly lead to dehydration, which can worsen your symptoms and contribute to weight loss. Drink plenty of water, clear broths, and electrolyte-rich drinks like sports drinks or oral rehydration solutions to replenish lost fluids. Avoid caffeinated or alcoholic beverages.

Eat a bland, low-fiber diet

When you're experiencing diarrhea, it's essential to eat foods that are gentle on your digestive system. The BRAT diet—bananas, rice, applesauce, and toast—is a well-known option. These foods are low in fiber and easy to digest, helping to bulk up your stool and reduce the frequency of diarrhea. You can also try adding baked chicken or plain potatoes to your meals.

Gradually reintroduce foods

If you’ve been avoiding certain foods due to your symptoms, reintroduce them gradually once your diarrhea improves. Keep track of what you eat in a food diary, noting any flare-ups that occur after consuming specific items. This will help you identify any potential food intolerances or sensitivities, which you can then address with the help of your healthcare provider.

Consider probiotics

Probiotics are beneficial bacteria that help restore balance to your gut microbiome. While research on the effectiveness of probiotics for managing diarrhea is ongoing, some studies suggest they may be helpful in cases of irritable bowel syndrome (IBS) or after antibiotics. Foods like yogurt, kefir, and kombucha are rich in probiotics, and supplements are also available. However, it’s best to consult a healthcare provider before using probiotics.

Seek professional care

If your diarrhea persists for more than a couple of days or you’re losing weight without trying, it’s essential to consult a healthcare provider. A thorough evaluation, including a physical exam, lab tests, and possibly imaging studies, can help identify the underlying cause of your symptoms.

Experiencing diarrhea and unintentional weight loss can be a sign of various underlying health conditions, from infections to chronic gastrointestinal disorders. If you’re struggling with these symptoms, it’s important to work with a healthcare provider who can help determine the cause and create a treatment plan tailored to your needs.