Screening for Weight Loss and Muscle Loss During Cancer

Weight loss and muscle loss are common and concerning problems during cancer. They may occur because you’re not eating enough, but they can also be caused by cancer-related changes in metabolism and inflammation. 

Left unchecked, poor nutrition and weight loss from cancer can lead to unintended weight loss, which can weaken your body, reduce muscle strength, and make it harder to tolerate treatment and recover. Regular nutritional screenings can catch weight loss early, so you can take steps to slow it before it compromises your health. 

Learn more about weight loss and cancer, how cancer can cause malnutrition, and why regular screening for weight loss can make a big difference in your treatment, recovery and well-being.

Unintentional weight and muscle loss are often warning signs that you’re not getting enough calories, protein and other key nutrients your body needs during the disease. Regular nutritional screenings can catch early changes in your weight, muscle mass and eating habits, so your healthcare team can intervene quickly and provide nutrition support. 

Up to 80% of people with cancer develop malnutrition, which can negatively affect treatments, recovery and quality of life (1). Poor nutrition status can contribute to fatigue and weakness, which makes it harder to recover and tolerate other treatments. (2) Malnutrition also taxes your immune system at a time when you need it most.

Nutritional screening is a standard part of quality cancer care and should be done at regular intervals. It usually involves checking your weight and height and answering a few short questions about your appetite, the foods you typically eat, and any symptoms that might make eating difficult or less enjoyable. 

Cancer and its treatments can dampen your appetite, impair digestion, and disrupt your metabolism. These factors often combine and lead to unintentional weight loss or loss of muscle mass and strength, a condition known as sarcopenia. 

Cancer itself triggers the release of inflammatory compounds that suppress your appetite and accelerate muscle breakdown. Tumours also alter how your body processes energy and nutrients from food, causing you to burn more calories than usual.

Certain cancers can cause weight loss or malnutrition because tumours make it hard to eat or digest food. Those most likely to affect nutrition include:

• Mouth, tongue, or throat cancers
• Oesophageal cancer 
• Stomach cancer
• Pancreatic cancer 
• Colorectal 

On top of that, many cancer treatments cause nutrition-related side effects that contribute to poor nutritional intake and further deteriorate nutritional status, such as:

• Loss of appetite
• Taste changes, including a metallic taste 
• Nausea or vomiting
• Extreme fatigue
• Mouth or throat sores
• Diarrhoea or constipation
• Stress or anxiety

Three widely used screening tools in cancer nutritional care are the MST (Malnutrition Screening Tool), PRONTO (PTOtocol for NuTritional Risk in Oncology) and the PG‑SGA (Patient‑Generated Subjective Global Assessment). These quick screening tools help identify people who may be at risk of malnutrition and who may benefit from a more detailed nutrition assessment by a healthcare professional or dietitian (3,4,5).

• The MST asks if you’ve had any unintentional weight loss or decrease in appetite that causes you to eat less.
• The PRONTO asks about weight loss over the past three to six months, any reduction in appetite or food intake, and any noticeable loss in physical strength.
• The PG-SGA includes questions you answer about your weight history, current diet, symptoms and physical activity, along with a physical exam and an assessment by your provider.

In between appointments, be on the lookout for these signs of poor nutrition or weight loss: 

• Changes in your usual appetite, like eating less, feeling full quickly, or struggling to finish a meal.
• Eating your normal diet but losing weight.
• Clothes that feel looser.
• Feeling physically weaker and unable to do your usual activities.
• Unplanned weight loss over a few weeks.

It’s easier to prevent weight loss and keep your body strong if you catch it early, so don’t wait. Contact your doctor if you notice any of these warning signs:

• Unintentional weight loss
• Difficulty eating
• Extreme fatigue
• Difficulty with daily tasks

If you’re concerned about weight loss or poor appetite, you can take the first step by using a simple online self-screening tool.

Everyone with cancer should have a nutritional screening, whether they have lost weight or not. If it’s been a while since you’ve had one, ask your doctor to screen you.

Detecting weight loss early, before it becomes severe, allows your medical team to provide nutritional intervention to help you maintain your strength, and support your nutritional status and tolerance to treatment.