Definition
Unexplained weight loss, or losing weight without trying — particularly if it’s significant or ongoing — may be a sign of a medical disorder.
The point at which unexplained weight loss becomes a medical concern is not exact. But many health care providers agree that a medical evaluation is called for if you lose more than 5% of your weight in 6 to 12 months, especially if you’re an older adult. For example, a 5% weight loss in someone who is 160 pounds (72 kilograms) is 8 pounds (3.6 kilograms). In someone who is 200 pounds (90 kilograms), it’s 10 pounds (4.5 kilograms).
Your weight is affected by your calorie intake, activity level and overall health. Your ability to absorb nutrients from the food you eat also affects your weight. Economic and social factors also may play a role.
Causes
Unexplained weight loss has many causes, medical and nonmedical. Often, a combination of things results in a general decline in your health and a related weight loss. Most often, medical disorders that cause weight loss include other symptoms. Sometimes a specific cause isn’t found.
Potential causes of unexplained weight loss include
Cancer
Dementia
Dental problems
Depression (major depressive disorder) or other mood disorders
Diabetes
Hypercalcemia (high blood calcium level)
Hyperthyroidism (overactive thyroid)
Hyponatremia (low blood sodium level)
Medicines
Parkinson’s disease
Previous stroke or neurological disorders
Less common conditions that may include weight loss as one of the symptoms are:
Addison’s disease (adrenal insufficiency)
Alcohol use disorder
Amyloidosis (buildup of abnormal proteins in your organs)
Celiac disease
COPD (chronic obstructive pulmonary disease) — the blanket term for a group of diseases that block airflow from the lungs — including emphysema.
Crohn’s disease
Drug addiction (substance use disorder)
Heart failure
HIV/AIDS
Peptic ulcer
Prescription drug abuse
Tuberculosis
Ulcerative colitis (a type of inflammatory bowel disease)