Loss of appetite

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on March 2, 2022.

Loss of appetite is a common and sometimes serious side effect of both cancer and cancer treatment. Whether you’re never hungry, feel full after eating very little, or consume less overall, this is a symptom you shouldn’t ignore. It’s important to maintain your caloric intake. You want to do what you can to ensure that your body gets the nutrients it needs to fight and recover.

What causes loss of appetite in cancer patients

Losing your appetite may be a direct result of your cancer or a side effect of treatment.

Tumors: A tumor may interfere with the body’s hunger signals in several ways.

Cancer treatment: Loss of appetite may follow most cancer treatments, from surgery to chemotherapy.

After surgery:

  • Recovery from surgery takes time, and you may not feel like eating for some time afterward, but this is exactly when you need extra nutrients.
  • Surgery on the digestive organs may cause complications such as pain and inflammation, leading to swallowing difficulties or digestive issues.

After other treatments:

  • Loss of appetite is a standalone side effect of chemotherapy, radiation and immunotherapy, often for the duration of the treatments.
  • A range of side effects may contribute to a loss of appetite.
    • Mouth sores, dry mouth and sore throat that make eating painful
    • Nausea and vomiting that make it tough to keep food down
    • Fatigue from treatment, making you too tired to eat
    • An altered sense of taste and smell that may make many foods unappealing
    • A persistent bad taste in the mouth

When to be concerned

Loss of appetite may sound like a minor inconvenience, but it has serious implications. Malnutrition due to appetite loss causes 20 percent of cancer deaths, according to an article in the Journal of Cachexia, Sarcopenia and Muscle.

Significant weight loss from an extreme breakdown of lean muscle mass is called cachexia, and it’s the result of a marked decrease in appetite and insufficient intake of nutrients. When this happens, protein, vitamin and mineral levels plummet, and the body weakens. The condition may quickly become life-threatening. Complications of cachexia include a decreased quality of life, reduction in immunity, increase in symptoms from the underlying cancer, and reduced life expectancy.

Reach out to your care team immediately if loss of appetite continues for more than a few days or if you experience any of the following:

  • Involuntary weight loss
  • A feeling of being extremely drained or chronically fatigued, or of general malaise
  • Fluid retention that’s causing swelling, most often in the legs

Managing loss of appetite

Take steps to regain your appetite, or at least to take in needed nutrients before you experience significant weight loss.

Tips for general loss of appetite

  • Drink plenty of water and other fluids. If you’re not eating, you’ll need to increase your intake of liquids to stay hydrated.
  • Try to get up and get moving if you can. Light activity, such as walking or yoga, is helpful in stimulating the appetite and preserving lean muscle mass.
  • Focus on eating small, frequent snacks instead of large meals. Choose nutrient-dense options and keep them within easy reach.
  • Eat on a schedule instead of relying on hunger cues, which may be nonexistent.
  • Eat with loved ones in a calm, relaxed setting.

Tips for dealing with side effects

  • Mouth sores: To help your mouth heal, try rinsing several times a day with a solution of 1/4 teaspoon baking soda and 1/8 teaspoon salt in a cup of warm water. Take ibuprofen or acetaminophen for pain, based on your doctor’s recommendation.
  • Dry mouth/sore throat: Increase your fluid intake and suck on ice cubes or lozenges. Try cold, soothing foods.
  • Nausea/vomiting: Bland, easy-to-digest foods are your best bet, and ginger or peppermint may be soothing when you’re experiencing nausea. If you’re vomiting, be sure you’re getting plenty of fluids and electrolytes.
  • Fatigue: Not eating may worsen fatigue. Prioritize protein and nutrient-rich foods to boost your energy level and help your body heal.
  • Loss of smell/taste: Try new foods and seasonings if your preferences have changed. You may have to stick with hyperpalatable options for the time being.
  • Bad taste in mouth: Mints, chewing gum and lozenges may be helpful.

If you aren’t hungry or find it increasingly difficult to eat due to pain or discomfort, discuss next steps with your care team. Your doctor may recommend one or more of the following interventions.

  • Nutritional counseling: Check in with an oncology-trained registered dietitian who has expertise in developing nutrition for cancer patients navigating loss of appetite.
  • Medications or supplementation: Your doctor may prescribe appetite stimulants and other medications. High-protein nutritional shakes may also be a helpful way to increase calorie intake.
  • Medical feeding interventions: The use of external nutritional support is common in cases of malnutrition.
    • Enteral nutrition: A feeding tube may be used to deliver nutrients directly into the stomach or intestines.
    • Parenteral nutrition: Vital nutrients, including protein, fat, carbohydrates, electrolytes, vitamins and minerals, may be infused directly into the bloodstream, bypassing the digestive tract.

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