Weight loss is hardly seen as a cause for concern due to the slim body ideal that has been popularised by the media. In light of this, weight loss that is intentional and is a result of dieting and exercise is considered healthy, provided it isn’t extreme.

Additionally, medical evidence demonstrates that if you are overweight, you’re more likely to be at risk of developing certain conditions that are detrimental to your health.

Despite this, however, unintentional weight loss is generally an important symptom signalling the development of a condition that requires medical attention. Regardless of the cause, there could be several underlying pathologies that need to be considered. If you’ve lost more than 5% of your body weight during the past 6 - 12 months without intending to, you may need to seek immediate medical attention.


There are many causes of unintentional weight loss and it is often a combination of factors that result in a general decline of your health. Sometimes a specific cause may not be found.

Potential medical causes of weight loss

Significant weight loss could be a symptom of a serious health condition, such as a physical or mental illness. These may include:

  • Dental issues
  • Malabsorption
  • Dysphagia
  • Thyroid issues such as hyperthyroidism or an overactive thyroid
  • Coeliac disease
  • Crohn’s disease
  • Ulcerative colitis
  • Inflammatory bowel disease
  • Pancreatitis
  • Stomach ulcers
  • Bacterial, viral or parasitic infection
  • Diabetes
  • Rheumatoid arthritis
  • Muscle loss
  • Chronic obstructive pulmonary disease (COPD)
  • Tuberculosis
  • Mental illnesses such as depression, anxiety, eating disorders, OCD or dementia
  • Eating disorders such as anorexia or bulimia
  • Chronic cardiac, respiratory, renal or liver disease
  • Cancers including that of the pancreas, lung, stomach, colon, and oesophagus

    Other causes of unintentional weight loss

    Unintentional weight loss doesn’t always have an identifiable cause, but it could also be the result of:

  • A side effect of certain medications
  • Substance abuse such as alcohol or drugs
  • Exhaustion
  • Loss of appetite
  • A change in your bowel movements
  • A change in your existing health conditions
  • A reaction or an allergy to certain food or beverages


If you are losing weight without trying to, it’s important to make an appointment to see your doctor even if you believe there is an explanation for your weight loss. While some of the medical causes of alarming weight loss can be difficult to diagnose, for some conditions, early detection could mean finding a path to recovery.

Your doctor may question you about your medical history, family history of chronic medical illnesses and your health and meal habits such as the content of your daily meals, your recreational habits, bowel movements, and daily water intake. Your doctor might also perform a physical exam.

Your doctor may also suggest you undertake a range of tests to confirm a diagnosis. These tests may include:

  • Blood tests
  • Liver function tests
  • Kidney function tests
  • Tests for inflammation
  • Imaging studies such as x-ray, CT scan or MRI
  • Endoscopy and colonoscopy
  • Stool and urine tests


Treatment for weight loss that isn’t intentional will depend upon the underlying cause(s). When the cause is determined, treatment may focus on the underlying condition or disease.

Apart from receiving condition-targeted treatment, your doctor may ask you to do the following to address the unintentional weight loss:

  • Maintain a well-balanced diet with essential nutrients
  • Eat an appropriate number of meals per day
  • Stop smoking, drinking alcohol or consuming drugs
  • Stop certain medications
  • Maintain a food journal
  • Get adequate exercise
  • Drink plenty of water
  • Control your intake of certain food or beverages
  • Maintain good dental hygiene
  • Keep away from food or beverages that may aggravate your weight loss
  • Consult a psychologist or psychiatrist

Request more information on the causes and treatment for unintentional weight loss


It is normal for a person’s weight to fluctuate. However, significant weight loss in a short time, without any intention to lose weight, can be the result of a serious, underlying health issue.

If you notice an alarming degree of weight loss in a short time, consult a doctor to learn more about how you can begin treatment before it causes serious complications.

Consult Dr Suhirdan Vivekanandarajah, an interventional gastroenterologist and hepatologist in Sydney, to find out more about the causes and possible treatment options for unintentional weight loss.

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