Definition

Unexplained weight loss, or losing weight without trying — particularly if it's significant or persistent — may be a sign of an underlying medical disorder.

The point at which unexplained weight loss becomes a medical concern is not exact. But many doctors agree that a medical evaluation is called for if you lose more than 5 percent of your weight in six months to a year, especially if you're an older adult. For example, a 5 percent 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, overall health, age, nutrient absorption, and economic and social factors.

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. Sometimes a specific cause isn't found.

Usually, an unrecognized cancer will have other symptoms or abnormalities of laboratory tests, in addition to unexplained weight loss.

Potential causes of unexplained weight loss include:

  1. Addison's disease (adrenal insufficiency)
  2. Amyloidosis (buildup of abnormal proteins in your organs)
  3. Cancer
  4. Celiac disease
  5. Changes in diet or appetite
  6. Changes in sense of smell
  7. Changes in sense of taste
  8. COPD (chronic obstructive pulmonary disease) exacerbation — worsening of symptoms
  9. Crohn's disease (a type of inflammatory bowel disease)
  10. Dementia
  11. Dental problems
  12. Depression (major depressive disorder)
  13. Diabetes
  14. Heart failure
  15. HIV/AIDS
  16. Hypercalcemia
  17. Hyperthyroidism (overactive thyroid)
  18. Hypothyroidism (underactive thyroid)
  19. Medications
  20. Parkinson's disease
  21. Peptic ulcer
  22. Substance abuse (alcohol, cocaine, other)
  23. Tuberculosis
  24. Ulcerative colitis

When to see a doctor


If you're losing weight without trying and you're concerned about it, consult your doctor — as a rule of thumb, losing more than 5 percent of your weight within six to 12 months may indicate a problem. If you're an older adult with many or more-serious underlying health issues, even a smaller amount of weight loss may be significant.

Your doctor will work with you to try to determine what's causing the weight loss. At first that will involve a thorough history, a physical examination and basic laboratory testing. Imaging scans to look for hidden cancers are not usually helpful unless some other clue points in that direction.

Sometimes, if the basic evaluation is negative, watchful waiting for one to six months is a reasonable next step. You may need a special diet to prevent further weight loss or to regain lost pounds.

Acanthosis nigricans

Addison's disease

Alcoholic hepatitis

Amyloidosis

Angina

Anorexia nervosa

Ascariasis

Aspergillosis

Bile reflux

Binge-eating disorder

Bone cancer

C. difficile infection

Cancer

Carcinoid tumors

Castleman disease

Celiac disease

Chronic lymphocytic leukemia

Chronic myelogenous leukemia

Churg-Strauss syndrome

Cirrhosis

Colon cancer

Congenital adrenal hyperplasia

Crohn's disease

Cryptosporidium infection

Cyclospora infection

Depression (major depressive disorder)

Dermatomyositis

Diabetes

Diabetes affects how your body uses blood sugar. Too much blood sugar over long periods can cause serious health problems, but treatments are available.

Diabetes insipidus

Diabetic neuropathy

Drug addiction (substance use disorder)

Dysphagia

Ebola virus and Marburg virus

Esophageal cancer

Ewing sarcoma

Fibromuscular dysplasia

Gallbladder cancer

Gastroparesis

Giant cell arteritis

Giardia infection (giardiasis)

Granulomatosis with polyangiitis

Graves' disease

Hairy cell leukemia

Helicobacter pylori (H. pylori) infection

Histoplasmosis

HIV/AIDS

Hodgkin's lymphoma (Hodgkin's disease)

Hyperthyroidism (overactive thyroid)

Hypopituitarism

Intestinal ischemia

Kidney cancer

Lead poisoning

Leukemia

Liver cancer

Lung cancer

Mesothelioma

Multiple myeloma

Neuroblastoma

Nonalcoholic fatty liver disease

Non-Hodgkin's lymphoma

Norovirus infection

Pancreatic cancer

Pancreatitis

Peptic ulcer

Pheochromocytoma

Pituitary tumors

Polymyalgia rheumatica

Postpartum thyroiditis

Postpartum thyroiditis — Overview covers the definition, symptoms and treatment for this postpartum condition affecting the thyroid.

Prescription drug abuse

Primary sclerosing cholangitis

Pulmonary fibrosis

Pyloric stenosis

Rectal cancer

Recurrent breast cancer

Rheumatoid arthritis

Seasonal affective disorder (SAD)

Sheehan's syndrome

Stomach cancer

Takayasu's arteritis

Tapeworm infection

Teen depression

Throat cancer

Thyroid nodules

Toxic hepatitis

Tuberculosis

Type 1 diabetes

Type 1 diabetes in children

Type 2 diabetes

Type 2 diabetes in children

Typhoid fever

Ulcerative colitis

Valley fever

Vasculitis

Vitamin deficiency anemia

Whipple's disease

Zollinger-Ellison syndrome