The short answer
Losing weight without trying — often defined as 10 pounds or more — can be an early sign of some cancers, though it has many other causes. Unexplained weight loss should be checked by a doctor.
Weight loss without trying can be an early sign of some cancers.
It is often one of the first noticeable signs of cancers of the pancreas, stomach, esophagus, or lung.
A loss of about 10 pounds or more with no clear reason is worth checking.
Many things other than cancer can cause weight loss, such as thyroid problems or stress.
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The full explanation.
The simple version
Losing weight without trying can be one of the first signs of some cancers. A drop of about 10 pounds or more with no clear reason is worth mentioning to a doctor — even though weight loss has many causes that are not cancer.
Why it can happen
Some cancers change how the body uses energy or affect appetite and digestion, leading to weight loss. It is often an early sign of cancers of the pancreas, stomach, esophagus, and lung, and can occur with many cancers as they advance.
Unintended weight loss is often an early sign of pancreatic, stomach, esophageal, or lung cancers.
Other causes
Weight loss is not specific to cancer. An overactive thyroid, diabetes, depression, stress, infections, and digestive conditions can all cause it. That is why a doctor's evaluation is needed to find the cause.
When to see a doctor
See a doctor if you have lost a noticeable amount of weight without trying, especially if it comes with other symptoms such as pain, fatigue, or a change in appetite.
Words to know
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Common questions
▸When is weight loss a concern?
Losing weight without trying to — often about 10 pounds or more — is worth checking. Weight loss you did not intend, especially with other symptoms, should be evaluated.
▸Which cancers cause weight loss?
Unexplained weight loss can be an early sign of several cancers, and is often first noticed with cancers of the pancreas, stomach, esophagus, or lung. Many cancers can cause weight loss as they advance.
▸Does weight loss always mean cancer?
No. Many conditions cause weight loss, including overactive thyroid, diabetes, depression, stress, and digestive problems. A doctor can help find the cause.
▸What should I do?
See a doctor if you have lost weight without trying, especially if it is significant or comes with other symptoms like pain, fatigue, or changes in appetite.
Questions to ask your doctor
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