What causes unintentional weight loss? 80 possible conditions

What Is Unintentional Weight Loss?

Unintentional weight loss is the process of losing weight without dieting or increasing physical activity. It may occur following a loss of appetite or when you are consuming the same amount of calories as usual. Either way, it is usually cause for concern.

Unintentional weight loss can be extremely distressing, particularly when you lose a relatively significant amount and don’t know why. Unintentional weight loss could be a sign of serious illness or disease, or something as minor as a stomach virus.

Unintentional weight loss is most prevalent in people with preexisting medical conditions. Some people who experience this symptom suffer from a variety of diseases including diabetes, AIDS, and depression.

What Causes Unintentional Weight Loss?

Unintentional weight loss is normally the result of an underlying chronic medical condition. However, short-term illnesses such as influenza or the common cold can also cause weight loss due to abdominal discomfort.

Common causes of unintentional weight loss include:

  • depression
  • diarrhea
  • oral ulcers
  • viral infections, such as the common cold, that can affect appetite

Other causes of unintentional weight loss include:

  • cancer
  • hyperthyroidism (overactive thyroid gland)
  • hypothyroidism (underactive thyroid gland)
  • abdominal infection
  • gastroenteritis
  • malnutrition
  • dementia
  • Celiac disease

Malnutrition occurs when you aren’t consuming a proper amount of nutrients. Malnutrition normally occurs as a symptom of a digestive disorder such as Celiac disease, which affects how the body absorbs nutrients, and can result in weight loss.

What Are the Symptoms of Unintentional Weight Loss?

Depending on what caused the weight loss, symptoms vary widely. The weight loss may be in one part of your body, or distributed all over. You may notice your waist, abdominal region, or arms and legs getting smaller. However, some people are unaware that they’ve lost weight until they weigh themselves.

Unintentional weight loss due to an illness may occur along with these symptoms:

  • fever
  • loss of appetite
  • abdominal discomfort
  • abdominal pain
  • diarrhea
  • constipation

Children who have unintentional weight loss may also have:

  • changes in appetite
  • fussiness over certain foods
  • physically smaller stature
  • abdominal pain
  • fever

Certain medications can cause unintentional weight loss as a side effect. If you are on any medication and experience a noticeable weight loss, consult with your doctor.

Visiting Your Doctor

Try to keep track of your weight loss. Note when the weight loss started. Also, make a note of any other symptoms you may have experienced around the time of noticing the weight loss. This will give your doctor useful information which can help in making a diagnosis.

Unintentional weight loss is a symptom of several conditions. Your doctor must go over your symptoms and any recent lifestyle changes you’ve made to know exactly what’s causing the weight loss.

Your doctor may ask the following questions:

  • Have you changed your diet?
  • Have you had a recent illness?
  • Are you less energetic than usual?
  • Have you had any digestive problems such as diarrhea or constipation?
  • Have you started taking any new medications?

If your doctor feels that your diet, a digestive disorder, or malnutrition is to blame, he or she may do a nutritional assessment. This may consist of a blood test that shows levels of specific vitamins and minerals. The results of this test will determine if you are deficient in any of these or if you have anemia.

Anemia occurs when your level of red blood cells is lower than usual. Iron deficiency or deficiency in a specific B vitamin can cause an anemia.

Blood tests can also be used to determine if a hormonal condition is to blame.

How Is Unintentional Weight Loss Treated?

If you are suffering from a nutritional deficiency, your doctor may refer you to a dietician or devise a diet plan that helps to correct the deficiency. A deficiency due to a digestive disorder, such as inflammatory bowel disease, will require a specialized diet to help you get the nutrients you need. This may include taking over-the-counter supplements.

Over-the-counter medications such as laxatives or fiber supplements may help correct temporary digestive issues such as constipation or diarrhea. However, always consult your doctor before trying any medication. Once the condition is corrected, the unintentional weight loss should subside.

Your doctor will likely prescribe medication if a hormonal disorder is causing the unintentional weight loss.

Unintentional weight loss due to general illnesses such as influenza, the common cold, or food poisoning may be corrected with:

  • bed rest
  • an increase in fluids
  • medications used to settle the stomach

In extreme situations, the doctor may administer food through a feeding tube in the hospital. This occurs when weight loss is so severe that you no longer have the energy to feed yourself or eating food alone will not help.

Article Sources:

Read More

See a list of possible causes in order from the most common to the least.


Nutritional Deficiencies (Malnutrition)

A nutritional deficiency occurs when the body doesn't absorb the necessary amount of a nutrient. Symptoms include a pale complexion, fatigue, hair loss, and depression.

Read more »


Lung Cancer Overview

Lung cancer is a cancer that originates in the lungs. Lung cancer often goes undetected in the early stages, since symptoms don't usually present themselves until the advanced stages of the disease.

Read more »


Liver Cancer

Liver cancer causes destruction of liver cells and interferes with the ability of the liver to function normally. Cancer that originates in the liver can spread from the liver to other parts of the body.

Read more »


Stomach Ulcer

Stomach ulcers are painful sores in the stomach lining or small intestine. They occur when the mucus that protects the stomach from digestive juices is reduced.

Read more »


Esophageal Cancer

Esophageal cancer occurs when a malignant (cancerous) tumor forms in the lining of the esophagus, which is the muscular tube responsible for moving food from the throat to the stomach. As the cancer grows, it can affec...

Read more »



Cirrhosis is severe scarring and poor function of the liver caused by long-term exposure to toxins such as alcohol or viral infections. Certain medications and disorder can also cause cirrhosis.

Read more »


Stomach Cancer (Gastric Adenocarcinoma)

Gastric cancer forms inside the stomach. Symptoms include pain or fullness in the stomach, nausea, and dark stool.

Read more »



Tuberculosis (TB) is a highly infectious disease that primarily affects the lungs. A severe and long-lasting cough, fever, and night sweats could indicate an active TB infection.

Read more »



Hepatitis is swelling and inflammation of the liver. It's usually caused by a viral infection. There are several types of hepatitis, including: A, B, C, D, and E. Symptoms may not occur until liver damage occurs.

Read more »


Peptic Ulcer

Peptic ulcers are sores that develop in the lining of the stomach, esophagus, or rarely in small intestine. They are usually caused by H. pylori, excessive NSAID or alcohol usage, smoking, or stomach cancer.

Read more »


Crohn’s Disease

Crohn's disease is a chronic bowel disease that causes severe inflammation of the digestive tract. It is associated with abdominal pain, diarrhea, and may affect your quality of life. Crohn's disease is characterized b...

Read more »



Colitis is inflammation of the colon, often causing discomfort and pain in the abdomen, as well as other gastrointestinal symptoms. Colitis has many possible causes, which determine the type.

Read more »


Addison’s Disease

Addison's disease occurs when the adrenal cortex is damaged and the adrenal glands don't produce enough of the steroid hormones cortisol and aldosterone.

Read more »



Achalasia is a condition of the esophagus -- the tube that carries food from the throat to the stomach -- which can cause food to get stuck. The cause of this condition can be difficult to find.

Read more »


Hookworm Infections

Hookworms are parasites that affect the small intestine and lungs. The first sign of infection is usually a rash where the parasite entered the skin, followed by diarrhea.

Read more »



There are many symptoms of the autoimmune disease HIV/AIDS, including persistent skin rashes, night sweats, and mouth sores.

Read more »



The thyroid gland produces a hormone that controls how your cells use energy (metabolize). Hyperthyroidism occurs when the body produces excessive amounts, causing rapid heart rates, weight loss, and heat intolerance.

Read more »


Lactose Intolerance

Lactose intolerence occurs when a person's small intestine can't break down lactose, an enzyme found in dairy foods. The condition can cause many gastrointestinal symptoms.

Read more »



Amebiasis is a parasitic infection, common in tropical countries and caused by contaminated water. Symptoms can be severe and usually start one to four weeks after exposure.

Read more »


Endometrial Cancer (Cancer of the Uterine Endometrium)

Endometrial cancer is a type of cancer that starts in the inner lining of the uterus. You are at greater risk if you are 60-70 years old and have used hormone replacement therapy that contains estrogen.

Read more »

This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.
Add another symptom to narrow down the possibilities

I'm experiencing:

Choose from list of symptoms: