The short answer
Losing weight without trying can have many causes, most of them not cancer — such as thyroid problems, diabetes, stress, or digestive conditions. Because it can also be a sign of some cancers, unexplained loss of about 10 pounds or more is worth getting checked.
Unexplained weight loss has many causes, most not cancer.
Thyroid problems, diabetes, stress, depression, and digestive issues are common causes.
Because it can signal some cancers, unexplained loss of about 10 pounds or more should be checked.
It is more concerning when joined by other symptoms.
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The full explanation.
The simple version
Losing weight without trying can be unsettling, but it has many possible causes, and most are not cancer. Because unexplained weight loss can occasionally be an early sign of cancer, though, it is one symptom worth checking rather than ignoring.
What usually causes it
Common causes include an overactive thyroid, diabetes, stress and anxiety, depression, digestive conditions such as celiac disease, infections, and changes in appetite or medicines. Many of these are straightforward to diagnose and treat.
Why it is worth checking
The National Cancer Institute notes that unexplained weight loss can be an early symptom of some cancers, including those of the pancreas, stomach, esophagus, and lung. Losing roughly 10 pounds or more without trying — especially with other symptoms such as tiredness, appetite loss, or pain — is worth a doctor's review.
When to see a doctor
See a doctor if you have lost about 10 pounds or more without trying, or any unexplained weight loss that comes with other symptoms. Simple tests can find common causes, and most of the time the explanation is not cancer.
Words to know
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Common questions
▸Does unexplained weight loss mean cancer?
Not usually. It has many causes, most not cancer — such as thyroid problems, diabetes, stress, or digestive issues. But it can be an early sign of some cancers, so it is worth checking.
▸How much weight loss is worth checking?
Unexplained loss of about 10 pounds or more, or any weight loss with other symptoms, is worth a doctor's review.
▸What non-cancer conditions cause weight loss?
An overactive thyroid, diabetes, stress, depression, infections, and digestive conditions are common causes.
▸Which cancers can cause weight loss?
Weight loss can be an early sign of cancers of the pancreas, stomach, esophagus, and lung, among others — but many other conditions cause it too.
Questions to ask your doctor
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