Unintentional weight loss

Sudden, noticeable weight loss can happen after a stressful event. It can also be a sign of a serious illness. The information on this page may give you a better idea of the cause of your weight loss. Don't use it to diagnose yourself. See your GP for a diagnosis.

About unintentional weight loss

It is often normal to lose a noticeable amount of weight after, for example, the stress of changing jobs, divorce, redundancy or bereavement.

Weight often returns to normal when you begin to feel happier. This can be after you've had time to grieve or get used to the change. 

Counselling and support may be needed to help you get to this stage. If you think you might need help in coping with stress, seek advice or speak to your GP.

Significant weight loss can also be the result of an eating disorder, such as anorexia or bulimia.

If you think you may have anorexia, try to seek help as soon as possible.

You could start by talking to a person you trust, such as a member of your family or a friend. You could perhaps ask them to go with you to see your GP.

There are also several organisations you can talk to for information and advice, such as the eating disorders charity Eating Disorders Association.

If your weight loss wasn't due to the above causes, and you didn't lose weight through dieting or exercising, see your GP. This is because you may have a health condition that needs to be treated.

How much weight loss is a concern

Your body weight can regularly fluctuate. But the persistent, unintentional loss of more than 5 per cent of your weight over 6 to 12 months is usually a cause for concern.

Losing this much weight can be a sign of malnutrition. This is when a person's diet doesn't contain the right amount of nutrients.

Other symptoms linked to unintentional weight loss can include:

  • tiredness
  • loss of appetite
  • a change in your toilet habits
  • an increase in illnesses or infections

Other common causes of unexpected weight loss

Unintentional weight loss doesn't always have an identifiable underlying cause. As well as the causes mentioned above, it's often the result of:

Less common causes of unexpected weight loss

Less often, unexpected weight loss may be the result of:

The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was reviewed February 2019

This page is due for review June 2022

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