Weight Changes

Weight changes during cancer treatment are common. There are a number of causes for weight loss including:

    • Eating less due to nausea or poor appetite
    • Diarrhea
    • Vomiting
    • Dehydration (not taking in enough fluid to make up for fluid that’s lost)

Causes for weight gain include:

    • Less activity
    • Eating more
    • Retaining water
    • Certain medicines

Quick weight loss is often a sign of dehydration, which can be serious. Weight changes of more than 5 pounds in a week should be reported to your cancer team. A decrease in weight over time may affect the patient’s ability to function, and make them weak and unable to perform daily activities. An increase in weight over time may suggest a serious health condition, such as diabetes or high blood pressure. You may be able to tell if you gain or lose 5 pounds in a week by the way you feel or the way your clothes fit, or you can weigh yourself on a scale every few days.

What to look for

    • Weight loss of 5 pounds or more in a week or less
    • Dry skin
    • Fatigue, weakness
    • Feeling very thirsty
    • Dizziness
    • Clothes or rings are too big

    OR

    • Weight gain of 5 pounds or more in a week or less
    • Swollen ankles
    • Shortness of breath
    • Feeling puffy or bloated
    • Tight shoes, clothes, or rings

What the patient can do

If you have lost weight

    • See the section called “ Fluids (lack of) and dehydration.” Be sure to drink enough water and other liquids.
    • Drink extra high-protein and high-calorie fluids between meals.
    • Eat high-protein foods. You may also try liquid food supplements.
    • Ask about meeting with a dietitian.

If you have gained weight

    • Ask if you need to limit fluid if your ankles are swollen.
    • Limit your salt intake.
    • Limit high-calorie foods.
    • Ask about meeting with a dietitian.

What caregivers can do

    • Weigh the patient at the same time every day and write it down along with the date. A good time is in the morning before eating or drinking.
    • Talk to the cancer team if the patient’s weight loss or weight gain concerns you.
    • Watch the patient for other symptoms.

Call the cancer team if the patient:

    • Loses or gains more than 5 pounds in a week
    • Has shortness of breath
    • Feels dizzy or becomes confused

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

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Last Medical Review: June 8, 2015 Last Revised: June 8, 2015

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