An introduction to cancer and weight loss

An introduction to cancer and weight loss

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An introduction to cancer and weight loss - mlanutrition

What is cancer?

Cancer is a disease where cells, the building blocks of all our organs and tissues, begin to behave abnormally, dividing uncontrollably to create more and more abnormal cells. These can form a lump called a tumour in a particular part of the body.

One of the first signs of cancer could be finding a lump – or tumour. Other cancer symptoms include feeling tired, unexpected pain, or unexplained weight loss (i.e. not due to a new diet or exercise regimen). A confirmed diagnosis can be a life-changing event for both the person diagnosed and their loved ones. When diagnosed with cancer you are likely to experience not only cancer signs as physical symptoms but also emotional stress and sometimes depression.

How is cancer treated?

Treatment for a cancer will depend on many factors, for example how big the tumour is, whether it has spread to other parts of the body and the general health of the person diagnosed. There are three main cancer treatment options: surgery (to try and remove the tumour) and radiotherapy or chemotherapy (to try and shrink the tumour).

The oncologist is the doctor who treats cancer and provides medical care for a person diagnosed with cancer. Whichever treatment – or combination of treatments – the person diagnosed is advised to undergo by the oncologist, it is important that their body is as strong as it can be before, during and after, to tolerate and recover from what can be a difficult process. However, weight loss, a common side effect of cancer and its treatment can leave the body weak1.

What types of cancer cause the most weight loss?

Cancer can happen in almost all parts of the body and can take a significant physical toll on the person diagnosed. But some cancers are more likely to cause serious physical challenges such as extreme weight loss2. These include gastrointestinal cancer (e.g. colon cancer, stomach cancer, bowel cancer and pancreatic cancer) as well as head and neck cancer (e.g. oral cancer, head cancer, neck cancer and lung cancer)2. For different reasons these cancers affect the ability of the those diagnosed to consume and digest food effectively2.

The impact of cancer on body strength

Keeping the body strong can be difficult during cancer because of several factors. The cancer itself and the body’s natural defense mechanisms can cause the person’s metabolic rate to rise, which can result in loss of body weight, particularly muscle (‘lean body mass’)3,4. Weight loss can be worsened by low appetite, nausea and taste changes, including when normal foods take on a metallic flavour, all of which can reduce food intake5.

The impact of weight loss on treatment success

Weight loss during cancer can have a negative impact on treatment because chemotherapy and radiotherapy doses are based on, amongst other factors, body mass index, or BMI. Cancer research shows any significant changes to BMI from the point of diagnosis, can result in the person diagnosed, receiving a suboptimal dose, or it could delay treatment altogether6. Besides chemotherapy and radiotherapy, BMI can also impact outcomes of surgery (if surgery is required7).

If the person diagnosed cannot get the nutrients they need to maintain or regain weight through a normal diet alone, your healthcare professional may recommend a high energy and protein nutritional supplement shake.

The role of nutritional supplements in cancer

Oral nutritional supplements come in a range of flavours and formats from nutritionally complete shakes to delicious ready-to-eat desserts. They can be taken between meals to support and boost the amount of nutrition consumed each day, or can be used if you are unable to eat at all, as some can be taken as a sole source of nutrition.

When started early with a cancer diagnosis, an oral nutritional supplement can contribute to weight maintenance, support continued cancer therapy and can provide better treatment outcomes. Taking an oral nutritional supplement in line with a healthcare professional’s advice can also help to reduce complications, reduce time in hospital and improve quality of life8.


  1. Ryan et al. Proc Nutr Soc, 2016;75(2)199-211.
  2. Bozzetti 2008 and 2001; Bosaeus 2001 Hebuterne et al, 2014 JPEN J Parenter Enteral Nutr.;38(2):196-204.
  3. DeWys et al. Am J Med, 1980;69:49;1-7.
  4. Prado CM et al. Cancer Chemother Pharmacol, 2011; 67(1):93-101.
  5. IJpma I, Timmermans ER, Renken RJ, et al. Nutr Cancer. 2017;69(1):140-145.
  6. Ross PJ et al, 2004 Br J Cancer; 90(10):1905-11.
  7. Medicine (Baltimore). 2015 Oct; 94(42): e1769. The Impact of Body Mass Index on the Surgical Outcomes of Patients With Gastric Cancer. A 10-Year, Single-Institution Cohort Study.
  8. Martin L et al. J Clin Oncol, 2015:33(1):90-9.
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