Unexplained weight loss: causes, warning signs & what to do
Losing weight without trying — especially more than 5% of your body weight over 6–12 months — should always be checked, as it can point to a treatable condition.
Common causes of unexplained weight loss
- Overactive thyroid (hyperthyroidism)
- Diabetes (new or poorly controlled)
- Depression or anxiety reducing appetite
- Digestive disease (coeliac, IBD, ulcers)
- Chronic infection (e.g. TB in some regions)
- Cancer (a less common but important cause)
When to see a doctor urgently
- Weight loss with coughing blood, or blood in stool/urine — seek prompt care
- Weight loss with night sweats and persistent fever
- Difficulty swallowing or a persistent change in bowel habit
- Any significant unintentional weight loss — get reviewed
Frequently asked questions
How much unexplained weight loss is concerning?
Losing more than about 5% of your body weight over 6–12 months without trying is worth investigating with your doctor.
What tests are done for unexplained weight loss?
Usually blood tests (thyroid, sugar, blood count, inflammation), sometimes imaging or endoscopy, guided by your other symptoms.
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MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.