Causes of Unintentional Weight Loss

What Does it Mean if I'm Losing Weight Without Trying?

woman standing on a scale
Understanding unexpected weight loss. Dkal Inc./Digital Vision/Getty Images

It seems the whole world is trying to lose weight, yet unexplained weight loss can be frightening. We’ve all heard of someone who lost weight for no reason and it turned out to be something bad. What are some possible causes of weight loss, what questions might your doctor ask, and what can you expect as you and your doctor seek to determine the cause?

What Is Unexplained Weight Loss?

Unexplained weight loss is defined as the unintentional loss of at least 10 pounds or 5 percent of body weight over a period of 6 to 12 months. This would be equivalent to a 200-pound man losing 10 pounds or a 130-pound woman losing six to seven pounds.

Weight loss may occur because you are eating less, or because your body is using nutrients differently due to a change in your metabolism or the growth of a tumor.

When to See Your Doctor

If you are losing weight without trying it is important to make an appointment to see your doctor, even if you think there is an explanation for your weight loss. It's important to be your own advocate and continue to ask they question why if you don't feel you have an adequate explanation. Ask for a second opinion if needed. Many of the conditions which can lead to unintentional weight loss are difficult to diagnose in the early stages.


If you have unintentional weight loss, your doctor will first take a careful history and do a physical exam. Depending on her findings, she may recommend further tests and radiology studies. 

Questions Your Doctor May Ask

  • When did you first notice that you were losing weight?
  • How fast have you been losing weight?
  • Have you made any changes in your diet or exercise schedule?
  • Have you ever had weight loss like this before?
  • How upsetting is the weight loss to you?
  • Are you having any other symptoms such as palpitations, shortness of breath, jaundice (a yellowish discoloration of the skin), a persistent cough, hoarseness, thirst, or a sensitivity to cold or heat?
  • How would you describe your general health compared to, say, a year ago?
  • Have you had screening tests recommended for someone your age such as a mammogram or colonoscopy, and what were the results?
  • Have you had any nausea or vomiting? Do you ever make yourself vomit?
  • Have you been constipated or had diarrhea?
  • Have you felt depressed or stressed lately?
  • Do you have any dental problems that pose difficulties with eating?
  • Are there any illnesses that run in your family?

Tests Your Doctor May Order

After asking questions and examining you, your doctor may recommend further tests. Some of them include:

  • Lab Tests – Tests commonly ordered include a complete blood count (CBC), electrolytes (metabolic panel), liver tests, kidney function tests, inflammatory tests (sed rate, C-reactive protein), blood sugar (glucose), urinalysis, and thyroid tests.
  • Radiology studies – Such as a CT of your chest or abdomen.
  • Procedures – Such as endoscopy or colonoscopy to evaluate your stomach and colon.


There are many reasons for unexplained weight loss, some serious, and some more of a nuisance.  In older adults (over the age of 65) the most common cause is cancer, followed by gastrointestinal and psychiatric conditions.  An overview of some causes include:


Unintentional weight loss is important not only in looking for an underlying cause (3/4 of people who have unexpected weight loss have an underlying cause found by their doctors) but because of what it means in regards to health.

Unintentional weight loss is linked with higher morbidity (development of illnesses) a higher mortality (higher death rate) and a lower quality of life for people suffering from many diseases. Cancer cachexia is a condition of unintentional weight loss combined with a few other concerns and is directly responsible for around 20 percent of cancer deaths. Even with coronary artery disease, it has been found that outcomes were 62 percent worse for people who experience unintentional weight loss.


The treatment of weight loss that isn’t intentional will depend upon the underlying cause or causes. Given the high likelihood of an underlying cause of the weight loss, anyone who has experienced weight loss without trying should have a thorough history and physical performed, in addition to other needed studies. Some of the causes of unintentional weight loss are fairly uncommon, and this may require several visits to determine a cause.

Regardless of the cause, measures should be taken to treat the weight loss as well. When a cause is determined, the weight loss itself is sometimes pushed to the back burner. If this is you, make sure to talk to your doctor about how you should treat this symptom. For those who are diagnosed with cancer, a palliative care consult should be considered. Palliative care teams do an excellent job of addressing concerns not directly related to cancer (for example, chemotherapy or radiation therapy) such as unintentional weight loss. Treatment of weight loss can, in turn, help people tolerate treatments for whatever the condition is that has caused weight loss.


Chen, S. et al. Evaluating probability of cancer among older people with unexplained, unintentional weight loss. Archives of Gerontology and Geriatrics. 2010. 50 Suppl 1:S27-9.

Gaddy, H., and K. Holder. unintentional weight loss in older adults. American Family Physician. 2014. 89(9):718-22.

Pack, Q., Rodriguez-Escudero, J., Thomas, R. et al. The Prognostic Importance of Weight Loss in Coronary Artery Disease: A Systematic Review and Meta-Analysis. Mayo Clinic Proceedings. 2014. 89(10):1368-77.

Thirunavukarasu, P. et al. Pre-operative unintentional weight loss as a risk factor for surgical outcomes after elective surgery in patients with disseminated cancer. International Journal of Surgery. 2015. 18:7-13.

Wu, J. et al. Evaluating diagnostic strategy of older patients with unexplained unintentional body weight loss: a hospital-based study. Archives of Gerontology and Geriatrics. 2011. 53(1):e51-4.