Unexplained weight loss: causes, related health conditions, and more

Medically reviewed by Rosanna Sutherby, PharmD on February 18, 2020. Written by Caitlin Boyd. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Have you recently noticed that your weight keeps going down—and you don’t know why? As it turns out, there are many possible causes of unexplained weight loss in men and women.

Read on to learn about the common causes of unintentional weight loss, related health conditions, common questions, and more.

Common causes of unexplained weight loss

Thyroid hormone imbalances

People with certain kinds of thyroid issues can experience unexpected weight loss. Why? The hormones in your body help control many vital functions, including your metabolism and appetite. If you have a thyroid hormone imbalance, you may experience involuntary weight loss as a symptom of hyperthyroidism, or overactive thyroid. To see if your thyroid hormones may indicate hyperthyroidism, consider taking the Everlywell at-home Thyroid Test. (Related: Hormone imbalance symptoms)

Gastrointestinal disorders

Unexplained weight loss in men and women may be a sign of certain gastrointestinal disorders like inflammatory bowel disease and peptic ulcers. These conditions can trigger involuntary weight loss due to malnutrition and pain experienced after eating. If you've been experiencing significant weight loss unexpectedly, be sure to talk with your healthcare provider as they may want to check if you have inflammatory bowel disease, chronic inflammation within the GI tract, or some other kind of digestive disorder.

Persistent discomfort in the abdomen like pain, cramps, or gas could also be associated with colon cancer. If you suspect that you have colon cancer, try an at-home colon cancer screening test.

Mental health conditions

Certain mental health conditions can affect your appetite and make eating a well-balanced diet difficult. Unexplained weight loss in women and men are common symptoms of anxiety and depression. People with depression and/or anxiety may experience a decreased appetite, for example, leading to a change in body weight. If you are experiencing depression and/or anxiety, talking with a mental health counselor or therapist (as well as a healthcare provider) is a great next step you can take.

Drug or alcohol abuse

Unexplained weight loss may be a symptom of drug or alcohol abuse. Alcohol and certain drugs can suppress appetite and, in the case of some substances, increase metabolism—which can result in unintentional weight loss.

Crohn's disease

Crohn's disease triggers inflammation inside your digestive tract. If you have Crohn's disease, you may notice:

  • Abdominal pain
  • Diarrhea
  • Fatigue
  • Blood in stool
  • Mouth sores
  • Fever

Without treatment, this chronic illness damages the tissue inside your digestive system, so your body may be unable to extract nutrients from food. Many people with Crohn's disease experience pain after eating.


Dementia can affect your appetite and eating patterns. Some people with dementia report changes in the taste or texture of your food. As a result, people with dementia may refuse to eat the food they've been served. This aversion to food often results in unintentional weight loss.


Hyperthyroidism develops when your thyroid gland produces too much of a particular hormone. This can increase your metabolism and trigger rapid weight loss.

The Everlywell at-home Thyroid Test lets you test your thyroid hormones from the convenience of your own home. This comprehensive test measures three main thyroid hormones, plus thyroid antibodies—and it’s easy to share your results with your healthcare provider. (Related: What are the best foods to help your thyroid?)

If you are diagnosed with a thyroid condition, treatment options may include medication, radiation therapy, or other methods.

Peptic ulcer disease

Peptic ulcer disease causes painful sores to develop in the lining of your stomach. These sores often cause stomach pain, bloating, and nausea or vomiting. Peptic ulcer disease can make eating undesirable (due to the pain it can cause after eating a meal) and trigger weight loss.

Celiac disease

For people with celiac disease, eating gluten-containing foods cause the immune system to damage the small intestine. This intestinal damage prevents the body from absorbing nutrients. Without treatment, celiac disease can lead to malnutrition and weight loss. If you have this chronic illness, it's important to speak with your healthcare provider to learn what they recommend for symptom management.

Chronic obstructive pulmonary disease (COPD)

COPD includes several progressive lung diseases that affect your breathing. People with COPD often have shortness of breath, wheezing, or a stubborn cough. Labored breathing can increase the number of calories you burn. Some people with COPD also lose their appetite. These factors often lead to unexplained weight loss and fatigue.

Seeking medical care for unexplained weight loss

In some cases, rapid weight loss can be a sign of cancer or a bacterial, viral, or parasitic infection, such as persistent gastroenteritis, tuberculosis (TB), or HIV and AIDS. For these reasons, it's always a good idea to discuss unexpected weight loss with your healthcare provider.

Treatment for weight loss depends on which condition is causing your symptoms. You may need to take medication or change your diet. If your weight loss is linked to a psychological disorder/mental health condition like depression, psychotherapy may help treat the condition and improve your appetite.

Common questions about unexplained weight loss

What is considered unexplained weight loss?

Unexplained weight loss is defined as a drop in body weight that doesn't have a clear cause. This definition doesn't include weight loss linked to dieting, increased activity, or other lifestyle changes.

What causes unexplained weight loss?

Unexplained weight loss can be a sign of a health issue, such as:

In people over age 65, sudden weight loss can be especially concerning. Your provider can help determine whether your significant weight loss puts your health at serious risk, as well as recommend any further testing if needed. To easily screen for colon cancer from the comfort of home, consider the Everlywell at-home colon test (fecal immunochemical test).

Unintentional weight loss can result from hyperthyroidism, or overactive thyroid, which is linked with high thyroid hormone levels. Easily check your thyroid hormones from the comfort of home with the at-home Thyroid Test.


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