Causes of unintentional weight loss
Unintentional weight loss can have many different causes.
It might be caused by a stressful event like a divorce, losing a job, or the death of a loved one. It can also be caused by a health condition or a combination of things.
Some causes of unintentional weight loss include:
- mental health conditions, such as depression, anxiety, eating disorders and obsessive compulsive disorder (OCD)
- problems with digestion, such as coeliac disease or inflammatory bowel disease (IBD)
- hormone conditions, such as an overactive thyroid or type 1 diabetes
- heart conditions, such as heart failure
- poor nutrition (malnutrition) or lack of appetite, although sometimes weight loss can happen when there's no change to a person's diet or appetite
- side effects of some medicines, such as levothyroxine, which is often used to treat an underactive thyroid (hypothyroidism)
Sometimes weight loss can be caused by cancer. It's important to get it checked if you're losing weight without trying.
Non-urgent advice: See a GP if:
- you keep losing weight without changing your diet or exercise routine
It's important to see a GP as soon as possible if you have weight loss and other symptoms. The earlier the cause is found, the sooner it can be treated.
Treatment for unintentional weight loss
Treatment for unintentional weight loss depends on what's causing it.
A GP will ask about your health and may arrange some tests or scans.
Depending on the possible cause, they may:
- advise you about things you can do to help, such as ways to reduce stress
- recommend treatment for any condition that's causing you to lose weight
- refer you to a specialist
Page last reviewed: 28 July 2025
Next review due: 28 July 2028