Weight Loss

Approved by the Cancer.Net Editorial Board, 04/2020

Weight loss is common among people with cancer. It may be the first visible sign of the disease. In fact, 40% of people say they had unexplained weight loss when they were first diagnosed with cancer. Weight loss associated with cancer may be different than other types of weight loss. Doctors refer to a weight loss syndrome called “cachexia,” which is characterized by increased metabolism, loss of skeletal muscle, fatigue, loss of appetite, and decreased quality of life. Cachexia is very common in patients with incurable cancer.

People with cancer also have other symptoms with weight loss:

  • 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 in people with cancer

Weight loss often starts with appetite loss. The underlying cancer and treatment-related side effects that may cause appetite loss are:

  • Changes in 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. Research strongly supports that palliative care be part of your cancer care earlier rather than later.

General tips

These tips may help patients who have cancer-associated appetite loss and weight loss:

  • Try to increase the frequency of the food you eat. Rather than trying to eat large meals 3 times daily, try instead to eat frequent small meals throughout the day. For example, eating small amounts every 3 hours may be a more successful strategy to increasing your food intake.

  • Consider consulting a registered dietitian (RD) or nutritionist. These professionals provide nutrition counseling. They help people maintain a healthy weight and get the important nutrients they need 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.

  • Prior to chemotherapy, eat light meals and avoid fatty or protein-rich foods. This may prevent developing a dislike of these foods if nausea or vomiting occurs.

  • You may want to keep a record of what, when, and how much you eat, including how you feel during and after eating. For example, do you have nausea? Feel full quickly? Notice changes in taste? Sharing this information with your health care team may help with decisions about changing your diet.


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

Megestrol acetate.
This is a progesterone hormone. It can improve appetite, weight gain, and sense of well-being. However, you need to discuss the risks of taking megestrol acetate with your health care team because of the increased risk of blood clots while taking this medication.

Steroid medications. Also called corticosteroids or glucocorticoids, these may increase appetite and improve your sense of well-being. They also may help with nausea, weakness, and pain. Doctors often only suggest steroids for short-term use for periods of less than 2 weeks. Despite the many benefits of steroids, long-term use is associated with many side effects, including, but not limited to, increases in blood sugar, increased risk of infection, and muscle weakness. It is important to note that doctors try to minimize the use of steroids for patients receiving immunotherapy.

Metoclopramide (Reglan). This is a medication used to help treat nausea and vomiting. Metoclopramide may also help prevent the feeling of fullness if you take it about 30 minutes before trying to eat a meal. One key side effect of this medication is that it may cause diarrhea.  

Pancreatic enzyme (lipase) replacement. The pancreas has a key role in helping digest food. For patients who may not have a fully functional pancreas, such as those with pancreatic cancer, supplemental digestive enzymes may help the body absorb fat, proteins, and carbohydrates. Signs that you may need to take supplemental digestive enzymes may include increased gas, bloating, vague abdominal pain, and stools that float in the toilet bowl. Be sure to let your health care team know if you have any of these symptoms.

Dronabinol (Marinol). This is a medication containing 1 of the active ingredients in medical cannabis called THC. THC may increase appetite but is also associated with a higher risk of confusion, especially in adults over the age of 65. Discuss the risks and benefits of taking dronabinol with your health care team, especially if you have never used medical cannabis previously or if you are taking other medications that may increase your risk of confusion (pain medications, anxiety medications).

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. An IV is inserted into a vein. The nutrients go directly into the body through the IV. Studies have demonstrated that the use of intravenous nutrient therapy should be limited to short periods. This is an artificial way of providing nutrition and therefore is associated with higher risks of infection and fluid building up in the body.

In most situations, this approach is not very helpful in patients with weight loss related to advanced cancer. In rare situations, like when there is a bowel obstruction, this approach may be tried. 

Weight loss versus cachexia

Weight loss and cancer cachexia are different. Cachexia is a syndrome that is caused by the underlying cancer. Although weight loss is part of cachexia, it is not associated with the increased metabolism that occurs with cachexia. Therefore, weight loss as part of cachexia does not always improve with more calories.

Cachexia in people with advanced cancer

Up to 80% of people with advanced cancer have cachexia. Cachexia is also called wasting. Wasting is when a person has both weight loss and muscle loss. Like other weight loss, cachexia can cause fatigue, weakness, loss of energy, and make it hard to do everyday tasks. People with cachexia may also experience more intense symptoms.

Cachexia can make it difficult for a person to cope with the physical demands of treatment. It may be helpful for people with cachexia to talk with a registered dietitian for a nutritional assessment and counseling. A registered dietitian gives patients and their caregivers advice about eating and feeding to help cope with cachexia and related side effects. This includes education around high-protein, high-calorie, nutrient-rich foods for when the patient wants to eat.  

Based on current scientific research, ASCO recommends not using any medication for treatment of cachexia as one acceptable option for management. In specific circumstances, doctors may try a short-term treatment with a progesterone hormone or steroid medication (see above). ASCO also does not recommend that people with advanced cancer and cachexia be fed through an IV or through a feeding tube due to possible complications, unless very specific conditions are present in otherwise reasonably fit individuals, such as a reversible bowel obstruction, short bowel syndrome, or other issues that cause problems with the absorption of nutrients.

This information is based on the ASCO guideline, “Management of Cancer Cachexia.” Please note that this link takes you to another ASCO website. Listen to a Cancer.Net Podcast on cancer cachexia to learn more.

Related Resources

Nutrition Recommendations During and After Cancer Treatment

Side Effects

Small Changes to Help Food Taste Better When You Have Cancer