Ask The Experts

Searching for causes behind unintentional weight loss

Q I am a healthy, 56-year-old woman. My height is 1.56m.

Two years ago, I weighed 45kg. However, a recent weight measurement shows that I now weigh 41kg.

I have not increased my physical activities and my diet, which consists primarily of vegetables, lean poultry meat, fish and brown rice, has remained largely constant.

Since 2000, I have been going for full-body check-ups every year. I was always given a clean bill of health.


Psychological factors can also result in weight loss. Worldwide, it is estimated that 9 to 24 per cent of patients who experience unintentional weight loss may have mental health conditions like stress or depression.

DR RUKSHINI PUVANENDRAN, on one of the possible causes of unintentional weight loss

I have consulted a general practitioner for my unexplained weight loss. She sent me for a chest X-ray and an ultrasound of the hepatobiliary system - the liver, gall bladder and bile ducts. The results were normal. She then advised me to consume an adult milk product.

Should I seek a second opinion or have more tests done?

Is there any particular food or nutrient that I may possibly be deficient in? Given that I am now taking the adult milk product, is there anything I should look out for?

A Unintentional weight loss can occur at any age, but it is more common when a person gets older.

This is defined as a weight loss of at least 5 per cent of one's body weight within six to 12 months, without the person reducing food intake or increasing energy expenditure. Such weight loss can arise from hormonal abnormalities, including thyroid and adrenal dysfunction.

Other causes include diabetes mellitus, gastric reflux and ulcers and autoimmune diseases.

These conditions are usually associated with other symptoms, especially if the weight loss occurs over several years. For example, a person with a stomach malignancy will suffer from abdominal pain and difficulty in swallowing, on top of losing weight. And people with auto-immune conditions usually have weight loss associated with joint swelling or pain, or even abnormal kidney function.

On the other hand, some medications can reduce one's appetite or cause gastrointestinal symptoms leading to weight loss. A thorough history-taking of your symptoms and medications, including items purchased over-the-counter, coupled with a standard series of tests, would usually detect any physical abnormalities.

It is also important to consider dietary factors. A person starting on a "healthy" diet, for instance, often consumes fewer calories, which can lead to weight loss too.

A poor appetite or overworking can also lead to a person eating less than usual.

Last but not least, psychological factors can also result in weight loss. Worldwide, it is estimated that 9 to 24 per cent of patients who experience unintentional weight loss may have mental health conditions like stress or depression. For example, a person may lose weight after the passing of a loved one.

Despite the many possible reasons for unexplained weight loss, for some people, a cause cannot be determined. This happens to 16 to 28 per cent of people with unintentional weight loss, according to worldwide studies.

It is fortunate that you have had screening blood tests done since year 2000. Any deviation of test results will offer clues to possible physical causes of your weight loss.

However, up to three in 10 people will have no physical or psychological causes for weight loss.

I must stress, however, that even if no definite cause can be found, being underweight in itself can be harmful to your health.

In people older than 50, being underweight can lead to osteoporosis (reduced bone density), sarcopenia (loss of muscle mass and strength) and nutritional deficiency.

Your previous body mass index (BMI) was a healthy 18.5. But you are currently underweight, with a BMI of 16.8.

You should try to eat more and return to your previous weight.

A diet of 1,800 calories a day over the next six months can help you gain weight to reach 45kg.

Having a food diary to track your food intake will be useful.

Nutritional drinks can be a useful adjuvant to increasing calorie intake if you have difficulty consuming enough calories. You may also consider consulting a dietitian.

Dr Rukshini Puvanendran

Consultant in the family medicine service at KK Women's and Children's Hospital

A version of this article appeared in the print edition of The Straits Times on January 12, 2016, with the headline 'Searching for causes behind unintentional weight loss'. Print Edition | Subscribe