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 weight. Unintentional weight loss is loss of 10 pounds (4.5 kilograms) or 5% of your normal body weight over 6 to 12 months or less without knowing the reason.

Loss of weight; Losing weight without trying; Unexplained weight loss

A loss of appetite may be due to:

• Feeling depressed
• Cancer, even when other symptoms are not present
• Chronic infection such as AIDS or tuberculosis
• Chronic illness, such as COPD or Parkinson disease
• Drug use such as amphetamines and cocaine
• Medicines, including chemotherapy medicines, and thyroid medicines
  
• Stress or anxiety

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

• Celiac disease
• Diarrhea and other infections that last a long time, such as parasites
• Chronic inflammation of the pancreas
• Removal of part of the small intestine
• Overuse of laxatives

Other causes such as:

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

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

Contact your 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 (4.5 kilograms) or 5% of your normal body weight over 6 to 12 months or less, and you do not know the reason.
• You have other symptoms in addition to the weight loss.

The 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?
• Have you been fainting?
• Do you have occasional uncontrollable hunger with palpitations, tremor, or 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.

Cederholm TE, Bosaeus IG. Malnutrition: assessment and support. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 198.

Manary MJ, Trehan I. Severe malnutrition. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 197.

McQuaid KR. Approach to the patient with gastrointestinal disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 118.

Seller RH, Symons AB. Weight gain and weight loss. In: Seller RH, Symons AB, eds. Differential Diagnosis of Common Complaints. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 36.