Weight Loss

Approved by the Cancer.Net Editorial Board, 09/2016

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

As many as 40% of people report unexplained weight loss when first diagnosed with cancer. And up to 80% of people with advanced cancer experience weight loss and cachexia. Cachexia is also called wasting. Wasting is the combination of weight loss and muscle loss.

Other symptoms often accompany weight loss and wasting:

  • Fatigue

  • Weakness

  • Loss of energy

  • Inability to perform everyday tasks

People experiencing cachexia often have difficulties coping with the physical demands of treatment. Additionally, they may experience more intense symptoms.

Causes of weight loss

Weight loss often begins with appetite loss. This may result from the following side effects of cancer or treatment:

Talk with your health care team about any symptoms you experience. In particular, mention new symptoms or a change in symptoms.

Managing weight loss

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

General tips

Controlling cancer-related weight loss is important for your comfort and well-being. These suggestions 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 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 recommend specific medications to address weight loss. Options include:

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

Steroid medications. These can increase appetite and improve sense of well-being. They also help with nausea, weakness, or pain. Doctors often recommend 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 stimulate appetite.

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

Intravenous nutrient therapy

Sometimes, doctors recommend receiving nutrients through an intravenous (IV) tube instead of eating and drinking. Typically, the goal is short-term nutritional support during recovery. A nurse inserts an IV into the vein. The nutrients go through the IV directly into the body. 

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.

More Information

Side Effects

Nutrition Recommendations During and After Cancer Treatment