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Unexplained weight loss

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Created: 24/11/2020
Edited: 30/01/2026
Written by: Sophie Kennedy

What is unexplained weight loss?

Unexplained weight loss is when you notice a significant drop in your body weight, especially when you are not trying to lose weight. Unlike when someone is intentionally trying to lose weight, this type of weight loss isn't due to a change of diet, activity or lifestyle, but instead comes on suddenly and is unexplained.

 

It is common for our weight to fluctuate over time; however, if you have noticed you’ve unintentionally lost more than 10 pounds, or five per cent of your body weight, over six to twelve months then it is considered ‘unexplained’ and you should seek health advice.

 

What causes unexplained weight loss?

Unexplained weight loss is typically a symptom of an underlying physical or psychological health problem, which is why you should see a doctor as soon as possible if you experience it. It can happen to anyone, but it more commonly occurs in people over the age of sixty-five.


Many health problems that range from mild to severe can cause unexplained weight loss. These can include but are not limited to:

  • Crohn’s disease
  • Heart failure
  • An over- or underactive thyroid
  • Cancer
  • AIDS
  • Depression
  • Anxiety
  • PTSD
  • Gastrointestinal problems
  • Malnutrition
  • Side effects from certain medications
  • Diabetes
  • Drug or alcohol abuse
  • Dementia
  • Dental problems
  • Eating disorders
  • Dysphagia


You should pay attention if you experience additional symptoms such as tiredness, a change in your toilet habits, loss of appetite and/or an increase in illnesses and infections. If so, it should also be reported to your doctor.

How is unexplained weight loss diagnosed?

To diagnose what is causing your weight loss, a doctor will likely ask you a series of questions and carry out a physical examination. Later, you may be required to undergo blood tests and have medical scans done, such as X-rays and MRIs.

How is unexplained weight loss treated?

Treatment for unexplained weight loss depends on the underlying condition. Once the condition is being properly managed and treated correctly, you may see your weight returning to normal. Your doctor may also refer you on to see a dietician for further advice on your diet.

Mr Deepak Hariharan
Written in association with: Mr Deepak HariharanSurgeon in Central London
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