Weight Loss

Approved by the Cancer.Net Editorial Board, 06/2019

Weight loss is common among people with cancer. It is often the first visible sign of the disease.

In fact, 40% of people say they had unexplained weight loss when first diagnosed with cancer. And up to 80% of people with advanced cancer have weight loss and cachexia. Cachexia is also called wasting. Wasting is when a person has both weight loss and muscle loss.

People with cancer also have other symptoms with weight loss and wasting:

  • Fatigue

  • Weakness

  • Loss of energy

  • Difficulty doing everyday tasks

People who have cachexia often have trouble coping with the physical demands of treatment. They may also have more intense symptoms.

Causes of weight loss

Weight loss often starts with appetite loss. Many side effects of cancer or its treatment may cause appetite loss:

  • Changes to the immune system or metabolism. Metabolism is the body’s process of breaking down food and turning it into energy.

  • Nausea and vomiting

  • Constipation

  • Mouth sores

  • Difficulty chewing

  • Difficulty swallowing

  • Loss of taste

  • Depression

  • Pain

Talk with your health care team about any symptoms you have. Tell them about new symptoms or a change in symptoms.

Managing weight loss

Relieving side effects is an important part of cancer care and treatment. This approach is called palliative care or supportive care. It helps meet the patient’s physical, emotional, and social needs.

General tips

It is important to manage cancer-related weight loss for your comfort and well-being. These tips may help:

  • Increase the amount of food you eat. Ask your health care team how much food you need.

  • Eat light meals and avoid protein-rich foods before cancer treatment. This may prevent developing a dislike of these foods if nausea or vomiting occurs.

  • Keep a record of what, when, and how much you eat. Include how you feel during and afterwards. For example, do you have nausea? Feel full quickly? Notice changes in how you taste the food? Share this information with your health care team. It will help with decisions about changing your diet.

  • Consider consulting a registered dietician (RD) or nutritionist. These professionals provide nutrition counseling. They help people maintain a healthy weight and get important nutrients such as protein, vitamins, and minerals. Ask your health care team for a referral. Or find a dietitian through the Academy of Nutrition and Dietetics.


Sometimes, doctors suggest certain drugs to curb weight loss. These drugs may include:

Megestrol acetate (Ovaban, Pallace). This is a progesterone hormone. It can improve appetite, weight gain, and sense of well-being.

Steroid medications. These can increase appetite and improve your sense of well-being. They also help with nausea, weakness, and pain. Doctors often suggest steroids for short-term use. Long-term use of steroids may cause serious side effects.

  • Metoclopramide (Reglan) can prevent feeling full before eating enough food.

  • Pancreatic enzyme (lipase) replacement helps the body absorb fat.

  • Dronabinol (Marinol), a cannabinoid made in the laboratory, may increase appetite.

  • Other medications are being studied to help people with cancer improve their appetite and gain weight.

Intravenous nutrient therapy

Sometimes, patients receive nutrients through an intravenous (IV) tube instead of eating and drinking. Usually, the goal is to provide short-term nutritional support to improve health. A nurse inserts an IV into the vein. The nutrients go directly into the body through the IV.

Nutrient therapy may help patients having difficulty chewing or swallowing. These problems are more common for people diagnosed with head and neck or esophageal cancers.

Related Resources

Nutrition Recommendations During and After Cancer Treatment

Side Effects

Small Changes to Help Food Taste Better When You Have Cancer