Unexplained weight loss is a decrease in body weight, when you did not try to lose the weight on your own.

Many people gain and lose some weight during any year. Loss of 10 pounds OR 5% of your normal body weight over 6-12 months or less, and you don't know the reason.

This problem may also be called unintentional weight loss.

Loss of weight; Losing weight without trying

A loss of appetite may be due to:

• Feeling depressed
• Cancer, even when other symptoms are not present
• Chronic infection such as AIDS
• Chronic illness, such as COPD or Parkinson disease
• Drugs, including chemotherapy drugs, and thyroid medications
• Drug abuse such as amphetamines and cocaine
• Stress or anxiety

Chronic digestive system problems that decrease the amount of calories and nutrients your body absorbs, including:

•  Diarrhea and other infections that last a long time, such as parasites
• Chronic swelling or infection in the pancreas
• Removal of part of the small intestine
• Overuse of laxatives

Other causes such as:

•  Eating disorders, anorexia nervosa that have not been diagnosed yet
• Diabetes that have not been diagnosed
• Overactive thyroid gland
  

Your healthcare provider may suggest changes in your diet and exercise program depending on the cause of your weight loss.

Call your health care provider if:

• You or a family member loses more weight than is considered healthy for their age and height.
• You have lost more than 10 pounds OR 5% of your normal body weight over 6-2 months or less, and you don't know the reason.
• You have other symptoms along with the weight loss.
  

The health care provider will do a physical exam and check your weight. You will be asked questions about your medical history and symptoms, including:

• How much weight have you lost?
• When did the weight loss begin?
• Has the weight loss occurred quickly or slowly?
• Are you eating less?
• Are you eating different foods?
• Are you exercising more?
• Have you been sick?
• Do you have any dental problems or mouth sores?
• Do you have more stress or anxiety than usual?
• Have you vomited? Did you make yourself vomit?
• Are you fainting?
• Do you have occasional uncontrollable hunger with palpitations, tremor, and sweating?
• Have you had constipation or diarrhea?
• Do you have increased thirst or are you drinking more?
• Are you urinating more than usual?
• Have you lost any hair?
• What medicines are you taking?
• Do you feel sad or depressed?
  
• Are you pleased or concerned with the weight loss?

You may need to see a dietitian for nutrition advice.

Bistrian BR. Nutritional assessment. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 221.