Definition

By Mayo Clinic Staff

Unexplained weight loss is losing weight without trying. A medical or mental health condition may cause this weight loss.

There isn't an exact number for when weight loss becomes a medical concern. In general, see your healthcare professional if you lose more than 5% of your weight in 6 to 12 months when you aren't trying to lose weight.

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).

Unexplained weight loss is more common in older adults and people who live in nursing homes.

Your calorie intake, activity level and overall health affect your weight. Also, your weight is affected by how well your body takes in and uses nutrients from food. Economic and social factors may play a role.

Unexplained weight loss also may be called unintended, unexpected or involuntary weight loss.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

We use the data you provide to deliver you the content you requested. To provide you with the most relevant and helpful information, we may combine your email and website data with other information we have about you. If you are a Mayo Clinic patient, we will only use your protected health information as outlined in our Notice of Privacy Practices. You may opt out of email communications at any time by clicking on the unsubscribe link in the email.

Dec. 19, 2025

See also

  1. 10 ways to avoid diabetes complications
  2. 6 tips to manage rheumatoid arthritis symptoms
  3. Acanthosis nigricans
  4. Achalasia
  5. Addison's disease
  6. Adenocarcinoma: How this type of cancer affects prognosis
  7. Adjuvant therapy for cancer
  8. Adrenal fatigue: What causes it?
  9. Amyloidosis
  10. Angina
  11. Anorexia nervosa
  12. Antidepressants and alcohol: What's the concern?
  13. Antidepressants and weight gain: What causes it?
  14. Antidepressants: Can they stop working?
  15. Antidepressants: Selecting one that's right for you
  16. Antidepressants: Side effects
  17. Antidepressants: Which cause the fewest sexual side effects?
  18. Artificial sweeteners: Any effect on blood sugar?
  19. Ascariasis
  20. Aspergillosis
  21. At-home colon cancer tests
  22. Atypical antidepressants
  23. B-cell lymphoma
  24. Bile reflux
  25. Binge-eating disorder
  26. Blood glucose meters
  27. Blood glucose monitors
  28. Blood sugar testing: Why, when and how
  29. Bone and joint problems associated with diabetes
  30. Bone cancer
  31. Burkitt lymphoma
  32. Caffeine: Does it affect blood sugar?
  33. Cancer blood tests
  34. Cancer pain: Relief is possible
  35. Cancer surgery
  36. Cancer survival rate
  37. Cancer survivors: Care for your body after treatment
  38. Cancer survivors: Late effects of cancer treatment
  39. Cancer survivors: Managing your emotions after cancer treatment
  40. Cancer-related diarrhea
  41. Cancer-related fatigue
  42. Carcinoid tumors
  43. Celiac disease
  44. Chemotherapy side effects: A cause of heart disease?
  45. Chronic lymphocytic leukemia
  46. Churg-Strauss syndrome
  47. Cirrhosis
  48. Cirrhosis self-care and diet
  49. Clinical depression: What does that mean?
  50. Colon cancer
  51. Colon Cancer Family Registry
  52. Colon cancer screening
  53. Colon cancer stool: What to look for and how to test at home
  54. Congenital adrenal hyperplasia
  55. Coronary artery spasm: Cause for concern?
  56. Crohn's Crisis
  57. Crohn's disease and the gut microbiome
  58. Curcumin: Can it slow cancer growth?
  59. Cutaneous B-cell lymphoma
  60. Depression (major depressive disorder)
  61. Depression and anxiety: Can I have both?
  62. Depression in women: Understanding the gender gap
  63. Depression, anxiety and exercise
  64. Dermatomyositis
  65. Diabetes
  66. Diabetes and depression: Coping with the two conditions
  67. Diabetes and exercise: When to monitor your blood sugar
  68. Diabetes and heat
  69. Diabetes and liver
  70. Diabetes diet: Should I avoid sweet fruits?
  71. Diabetes foods: Can I substitute honey for sugar?
  72. Diabetes management: How lifestyle, daily routine affect blood sugar
  73. Diabetes treatment: Can cinnamon lower blood sugar?
  74. Diabetic Gastroparesis
  75. Diabetic neuropathy
  76. Diffuse large B-cell lymphoma
  77. Does stress make rheumatoid arthritis worse?
  78. Dr. Mark Truty (surgery, MN) better outcomes with chemo
  79. Drug addiction (substance use disorder)
  80. Early HIV symptoms: What are they?
  81. Eating disorder treatment: Know your options
  82. Eating disorders
  83. Eating during cancer treatment: Tips to make food tastier
  84. Esophageal cancer
  85. Ewing sarcoma
  86. Fatty liver disease (MASLD)
  87. Fatty liver disease (MASLD) diet
  88. Fecal transplant treatment of C. difficile at Mayo Clinic
  89. Fibromuscular dysplasia
  90. Floor of the mouth cancer
  91. Follicular lymphoma
  92. Gallbladder cancer
  93. Gallbladder polyps: Can they be cancerous?
  94. GI Stents
  95. Giant cell arteritis
  96. Giardia infection (giardiasis)
  97. Glycemic index: A helpful tool for diabetes?
  98. Grateful patient talks about his Mayo Clinic experience
  99. Graves' disease
  100. Hairy cell leukemia
  101. Heart cancer: Is there such a thing?
  102. Helicobacter pylori (H. pylori) infection
  103. Hepatocellular carcinoma (HCC)
  104. High-dose vitamin C: Can it kill cancer cells?
  105. Hilar cholangiocarcinoma
  106. Histoplasmosis
  107. HIV/AIDS
  108. Hodgkin lymphoma (Hodgkin disease)
  109. Hodgkin vs. non-Hodgkin lymphoma: What's the difference?
  110. How cancer spreads
  111. How do I reduce fatigue from rheumatoid arthritis?
  112. How to tell if a loved one is abusing opioids
  113. Hyperinsulinemia: Is it diabetes?
  114. Hyperthyroidism (overactive thyroid)
  115. Hypopituitarism
  116. Infographic: Cancer Clinical Trials Offer Many Benefits
  117. Infographic: Lung Cancer
  118. Infographic: Multiple Myeloma
  119. Infographic: Pancreatic Cancer: Minimally Invasive Surgery
  120. Infographic: Pancreatic Cancers-Whipple
  121. Infographic: Pancreatic Neuroendocrine Tumors
  122. Insulin and weight gain
  123. Intestinal ischemia
  124. Is depression a factor in rheumatoid arthritis?
  125. Is there a special diet for Crohn's disease?
  126. Kidney cancer
  127. Kidney Cancer
  128. Kidney cancer FAQs
  129. Kratom for opioid withdrawal
  130. Kratom: Unsafe and ineffective
  131. LADA
  132. Lead poisoning
  133. Leukemia
  134. Liver cancer
  135. Liver cancer FAQs
  136. Low blood counts
  137. Lung cancer
  138. Lymphoma
  139. Lymphoma FAQs
  140. Male depression: Understanding the issues
  141. Mantle cell lymphoma
  142. MAOIs and diet: Is it necessary to restrict tyramine?
  143. Marginal zone lymphoma
  144. Marijuana and depression
  145. Mayo Clinic Minute: Avoid opioids for chronic pain
  146. Mayo Clinic study reporting increased incidence of C. difficile infection
  147. Medications for type 2 diabetes
  148. Mesothelioma
  149. Mort Crim and Cancer
  150. Multiple myeloma
  151. Myths about cancer causes
  152. Natural remedies for depression: Are they effective?
  153. No appetite? How to get nutrition during cancer treatment
  154. Non-Hodgkin lymphoma
  155. Norovirus infection
  156. Opioid stewardship: What is it?
  157. Pain and depression: Is there a link?
  158. Pancreatic cancer
  159. Pancreatic Cancer Survivor
  160. Pancreatic neuroendocrine tumors
  161. Pancreatitis
  162. Peptic ulcer
  163. Peritoneal carcinomatosis
  164. Pheochromocytoma
  165. PICC line placement
  166. Pituitary tumors
  167. Prescription drug abuse
  168. Prostate cancer recurrence
  169. Protect your joints while housecleaning
  170. Pulmonary fibrosis
  171. Pyloric stenosis
  172. Reactive hypoglycemia: What can I do?
  173. Rectal cancer
  174. Recurrent breast cancer
  175. Rethinking Rheumatoid Arthritis
  176. Rheumatoid arthritis
  177. Rheumatoid arthritis
  178. Rheumatoid arthritis and exercise
  179. Rheumatoid arthritis: Can it affect the eyes?
  180. Rheumatoid arthritis: Can it affect the lungs?
  181. Rheumatoid arthritis: Does pregnancy affect symptoms?
  182. Ricin poisoning
  183. Salt craving: A symptom of Addison's disease?
  184. Seasonal affective disorder treatment: Choosing a light box
  185. Self-care for fatty liver disease (MASLD)
  186. Self-Image During Cancer
  187. Small cell, large cell cancer: What this means
  188. Stage 4 (metastatic) colon cancer
  189. Staying active with Crohn's disease
  190. Takayasu's arteritis
  191. Tapering off opioids: When and how
  192. Tapeworm infection
  193. Teen depression
  194. The dawn phenomenon: What can you do?
  195. Throat cancer
  196. Thyroid disease: Can it affect a person's mood?
  197. Thyroid nodules
  198. Tips to make your mornings easier
  199. Treatment-resistant depression
  200. Tuberculosis
  201. Tumor vs. cyst: What's the difference?
  202. Type 1 diabetes
  203. Type 1 diabetes FAQs
  204. Type 1 diabetes in children
  205. Type 2 diabetes
  206. Type 2 diabetes in children
  207. Types of diabetic neuropathy
  208. Typhoid fever
  209. Ulcerative colitis flare-ups: 5 tips to manage them
  210. Using insulin
  211. Valley fever
  212. Vasculitis
  213. Vegetarian diet: Can it help me control my diabetes?
  214. Vitamin B-12 and depression
  215. Vitamin deficiency anemia
  216. Vitamins and supplements for fatty liver disease (MASLD)
  217. Waldenstrom macroglobulinemia
  218. What are opioids and why are they dangerous?
  219. What is cirrhosis? A Mayo Clinic expert explains
  220. What is Crohn's disease? A Mayo Clinic expert explains
  221. What is depression? A Mayo Clinic expert explains.
  222. What is kidney cancer? An expert explains
  223. What is lymphoma? An expert explains
  224. What is stomach cancer? A Mayo Clinic expert explains
  225. What is type 1 diabetes? A Mayo Clinic expert explains
  226. What is ulcerative colitis? A Mayo Clinic expert explains
  227. When cancer returns: How to cope with cancer recurrence
  228. Where can I learn more about living with Crohn's disease?
  229. Whipple's disease
  230. Zollinger-Ellison syndrome