Cancer and weight loss: What you need to know

How your diet can affect your cancer treatment and the tips to know, to stay well nourished.
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Cancer patients are prone to weight loss during treatment and recovery. This weight loss can affect your cancer treatment; you need to keep the weight up to continue with the therapies and treatments. In fact, recent study has shown that patients who lose more than 5 per cent of their body weight have poorer treatment outcomes1.

Professor Koo Wen Hsin, senior consultant from the National Cancer Centre Singapore shares more about the top nutrition tips to know.

The causes of weight loss

There are two types of weight loss that cancer patients tend to experience. The first is a simple protein-calorie malnutrition, which basically means that the patient is not eating enough. This typically results in the loss of body fat. When someone is diagnosed with cancer, they can get depressed which affects their mood and discourages them from eating. Sometimes the chemotherapy and drugs can affect their appetite.

Surgery done in relation to the cancer can also alter the anatomy and function of the intestines, which makes it difficult for the patient to digest and absorb the nutrition needed from the food he or she eats.

The second type of weight loss is called cachexia. This is more difficult to manage as patients continue to lose weight in spite of a very good, adequate nutrition intake.

Unlike the weight loss due to lack of nutrients, cachexia causes the patient to lose lean muscle mass. When the patient loses muscle weight, they become weak and easily fatigued.

You feed the patients as much as you can but they will not put on weight — they will even continue to lose weight.This is because of the pathological processes caused by cancer in the body. This tends to happen to patients who are at an advanced stage of cancer.

Why weight loss matters

Cancer patients who are very weak due to weight loss can’t withstand the effects of surgery so they may be forced to drop out of treatment. If they are able to continue with treatment, the chemotherapy dosage and frequency of treatment may have to be reduced, which can affect how effective the treatment can be.

When patients become weaker from weight loss, they spend more time in bed, which can cause infections, thrombosis and blood clots. They may become less sociable and get depressed about their dramatic weight loss and changes in appearance. This in turn, affects their overall quality of life and how they respond to the treatment and thus the outcome of their treatment.

It’s essential to help loved ones who are undergoing cancer treatment to maintain their weight; don’t wait until they start losing weight before intervening.

Tips to know

Maintaining your weight is important, during the treatment. It’s possible to do so even with cachexia, by following good and sound advice from the dietician and other nutrition experts. Get your dietician to chart your diet history, to find out exactly what you’ve been eating.

  • Be strategic about the food that you eat. Choose food that’s low in volume but high and dense in nutrients. If you can’t eat, take nutrient-dense beverages so that you will still get the nutrition you need.
  • Be creative with your meals. Change the texture, temperature and taste of foods so that you can eat the right types and quantities of food. Eat a varied and balanced diet from the four food groups: whole grains, fruits, vegetables and meat. Avoid trans fats, processed meats and alcohol.
  • Enrich the foods you eat and make every mouthful count. For example, avoid taking porridge on its own; you could add ingredients such as minced meat, fish, egg or tofu to porridge. Or add milk to your bowl of cereal or oatmeal. Use oral nutritional supplements to help boost your calorie and nutrient intake.
  • Take your meals on time. Do make sure to take your meals when it’s time to eat, rather than waiting until you’re hungry.
  • EPA, omega-3 fatty acids can help stop and prevent cancer cachexia, as these essential fatty acids help reduce the inflammatory and pathology processes that cause weight loss. In a cancer patient’s body, the blood and tumours produce a lot of proteins and chemical compounds that case this inflammatory reaction. There are also treatments that can help prevent weight loss, through the use of medicines and other processes to help control the pathological and biochemical changes caused by cancer.

When to see a doctor

If weight loss persists, do consult your doctor. For some people, weight loss can be an early sign of an undiagnosed cancer. For others, weight loss occurs only as the cancer and its treatment reach an advanced stage.

Without proper intervention, this can progress to a condition called cancer cachexia, which is characterised by ongoing muscle wasting, with or without the loss of body fat. Cancer cachexia can lead to reduced response to therapy, as well as more health complications and infections, a lower quality of life and reduced survival.

Unintended weight loss in cancer patients is different from other types of weight loss as it is mainly due to metabolic changes caused by the tumour. It may not be as easily reversed even when you increase your calorie intake.

Therapy for weight loss in cancer patients thus needs to address the underlying metabolic abnormalities in order to be effective, and should begin as early as possible.

Consumption of an oral nutrition supplement containing Eicosapentaenoic acid (EPA), an omega-3 fatty acid, has been shown to result in improved outcomes such as weight gain, maintenance of lean body mass, reduced treatment interruptions and improved quality of life.

This article was adapted from the 'Eating Well During Cancer' booklet by Singapore Cancer Society and Abbott.

1'Evaluation of effect of body mass index and weight loss on survival of patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy'. Lin, Yu-Hsuan; Chang, Kuo-Ping; Lin, Yaoh-Shiang, and Chang, Ting-Shou. Retrieved on Nov 26, 2015 from: