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