Weight Loss as a Symptom of Cancer

Unintentional weight loss without dieting or exercise can be a pleasant surprise. However, unexplained weight loss could be the first warning sign of a serious health issue including thyroid disorders, diabetes, and cancer. This is especially true for those experiencing loss of more than five percent of body weight over the course of six to 12 months. 

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Weight loss occurs among people with cancer and can be the first sign of the disease. In fact, 40% of people say they had unexplained weight loss when first diagnosed with cancer.

On its own, it cannot diagnose cancer but can alert healthcare providers to perform diagnostic tests to see if cancer is the cause.

This article reviews how weight loss can be attributed to cancer and what to do if you have unintentional weight loss.

Weight Loss and Cancer

Weight loss isn’t characteristic of any single type of cancer. It can occur whether a person has colon cancer, lung cancer, breast cancer, liver cancer, or lymphoma.

Studies most frequently attributed weight loss to cancer in the following types of cancers:

  • Biliary tree
  • Colorectal
  • Gastro-esophageal
  • Lung
  • Myeloma
  • Non-Hodgkin’s lymphoma
  • Ovarian
  • Pancreatic
  • Prostate
  • Renal (kidney)

The causes of weight loss vary, although the loss of appetite, fatigue, and nausea are common root causes. In some cases, gastrointestinal problems can contribute to weight loss, including diarrhea and infections of the mouth or esophagus. At other times, there may be an emotional component, such as depression or anxiety, that prevents one from eating properly or getting the nutrition they need.

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What To Do

It is generally a good idea to contact your healthcare provider if you have unintentionally lost five percent of your usual weight within six to 12 months. Your healthcare provider will assess your symptoms to see if they indicate a specific illness.

During your appointment, your healthcare provider may ask the following questions:

  • Do you have any dental problems, bleeding, or pain preventing eating?
  • Have you had any vomiting?
  • Do you have diarrhea?
  • What are your stress levels like?
  • Have you experienced any major changes in your life?
  • Do you eat the same as normal or less than usual?
  • Are you a smoker?
  • Do consume alcohol and, if so, how much?
  • What other symptoms do you have?

It is important to make your healthcare provider aware of any diseases or conditions may have, as well as all medications, prescriptions, or otherwise, that you may be taking.

After the initial consultation, they will likely order a few routine blood tests, including the following.

  • A complete blood count (CBC): A CBC provides information about specific types of blood cells. It is useful for detecting anemia, fatigue, blood loss, infection, and how well your blood is carrying oxygen to the tissues in your body. It also looks for an elevated platelet count, which could indicate cancer.
  • Chemistry panel: A chemistry panel is a comprehensive metabolic panel (CMP) and is often referred to as a chem 7 or chem 8. It gives your provider information about kidney function, minerals, electrolytes, liver enzymes, hydration, blood sugar, and more.
  • Erythrocyte sedimentation rate (ESR or sed rate): Sed rates measure certain proteins. It can detect an underlying inflammation indicative of an infection, autoimmune disorder, or cancer.
  • C-Reactive Protein (CRP): CRP is a protein in the liver. High levels can indicate inflammation.

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These sorts of insights allow practitioners to narrow their search based on what the tests tell them.


Weight loss is not a symptom of all types of cancer. It can be caused for a variety of reasons. Sometimes weight loss is directly related to cancer, but other factors such as emotional distress and side effects of treatment can contribute to weight loss. Recent research shows that it can occur at any stage. 

If you have lost more than five percent of your body weight in the last six to 12 months, notify your provider. They will ask you various questions and order diagnostic blood tests to determine the root cause.

A Word From Verywell

Unexplained weight loss can be stressful. Keep in mind that it is not always an indication of cancer. It is simply a sign that your provider should run tests to ensure that cancer is not the cause.

If cancer is found, early identification is always better. Early detection leads to early treatment, which increases success rates. It also ensures that you are provided medications to treat the symptoms related to weight loss, whether it be an anti-diarrheal, appetite stimulant, antidepressant, or oral antibiotic.


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About the Author: Tung Chi