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Unexplained weight loss

Unexplained weight loss: A common gastroenterological phenomenon

Unexplained weight loss or losing weight without trying to might be a cause for concern as it can indicate an underlying medical condition. It may occur without a change in your diet or exercise routine, due to seasonal changes or due to stressful life events.

Owing to certain severe consequences of gaining too much weight, there tends to be more of a focus on ways to lose weight. However, unexplained weight loss– which is where you lose more than 5% of your weight between 6 to 12 months – could jeopardise your physical and psychological health.

If you have experienced weight loss on this scale, speak to a doctor and they will be able to help you understand if there’s a medical cause for this. They may perform a physical examination, ask you about your medical history, and request blood, urine, and stool samples or other imaging reports to accurately diagnose any underlying conditions.


Unexplained weight loss could be caused due to several medical conditions. Apart from physiological conditions, it could also be caused by certain psychological challenges as well.

If you wish to see a doctor, keep an eye out for any other symptoms you may be experiencing, as it could help your doctor make a more accurate diagnosis.

Inflammatory bowel disease (IBD)

IBD refers to the two chronic inflammatory disorders of the digestive tract, namely Crohn’s disease and Ulcerative colitis. While Crohn’s disease can cause inflammation in any part of the gastrointestinal tract, from the mouth to the anus, ulcerative colitis affects only the large intestine.

IBD can reduce the body’s ability to digest food properly, resulting in malnutrition and unexplained weight loss. IBD also disrupts the hunger and satiety hormones, leading to decreased appetite.

Other symptoms include:

  • Frequent diarrhoea
  • Abdominal pain
  • Bloody stools
  • Fatigue
  • Fever

The symptoms of IBD are most often triggered by certain food items. Therefore, your treatment options may include nutritional support, medication or surgery.

How is inflammatory bowel disease prevented?

Inflammatory bowel disease has no known cause and some theories suggest that it may be hereditary and cannot be prevented.

IBD can happen to anyone, but the chances of getting IBD may be reduced by:

  • Exercising regularly
  • Giving up smoking
  • Eating healthy fibre-rich food

Can IBS cause loss of appetite and weight loss?

IBS is different from IBD as it is more of a nerve-related problem. It cannot directly affect a person’s weight but the symptoms may cause patients to avoid certain foods, which may lead to weight loss.

Coeliac disease

Coeliac disease is characterised by your body’s inability to process gluten, a protein found in wheat, barley, and rye. If you have coeliac disease and you consume gluten, your immune system will attack your intestinal wall, resulting in malnutrition.

Additional symptoms of coeliac disease include:

  • Abdominal pain
  • Chronic diarrhoea
  • Constipation
  • Foul-smelling stool

As a part of your treatment, you may be advised to avoid eating gluten. You must do so under the guidance of a medical professional to ensure that you are cutting out all forms of gluten but are still receiving necessary nutrients.

Peptic ulcer disease

Peptic ulcer disease is characterised by open sores in the stomach, upper intestine, or oesophagus. Caused either by bacterial infections or certain medications, these sores are a result of your stomach acid eroding the protective mucous layer in your digestive tract.

Due to the body’s resulting difficulty to absorb nutrients, peptic ulcer disease can lead to serious complications if left untreated for long. It can also lead to severe symptoms such as blood in your vomit or bloody stools.

Apart from the unexplained weight loss, if you have peptic ulcer disease, you may also experience additional symptoms such as:

  • Pain in the upper abdomen
  • Bloating
  • Feeling full after eating a little
  • Loss of appetite


The symptoms of different types of cancer vary depending on the type, stage, and location of the disease. Unexplained weight loss is a common symptom.

Cancers that affect the digestive tract include:

  • Pancreatic cancer
  • Colorectal cancer
  • Liver cancer
  • Stomach cancer
  • Bowel cancer
  • Oesophageal cancer

Other early symptoms of cancer to pay attention to are:

  • Fatigue
  • Fever
  • Changes in bowel function
  • Skin changes
  • A persistent cough

What other bowel problems cause weight loss?

  • Pancreatitis
  • Lactose intolerance
  • Cirrhosis of the liver

How can I improve digestion and reduce weight loss?

  • Eat unprocessed foods
  • Drink lots of fluids
  • Eat more fatty foods
  • Eat high fibre foods
  • Eat fermented foods

Request more information about the symptoms and causes of unexplained weight loss

While your body weight can fluctuate naturally, it’s important to consult a doctor if you lose your baseline body weight without any intentional changes to your lifestyle or habits. Your doctor may be able to accurately diagnose the underlying cause of your unexplained weight loss if you’ve remained mindful of any other changes you’ve been experiencing.

For more information on the causes and treatment options for unexplained weight loss, speak to a team of trained gastroenterologists at the Sydney Gut Clinic.