Weight Gain

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

Some people lose weight during cancer treatment while others gain weight. Slight increases in weight during cancer treatment are generally not a problem. But significant weight gain can affect a person's health.

Weight gain is an especially important health issue for women with breast cancer. More than half of women with breast cancer experience weight gain during treatment. Reports show that weight gain during treatment is linked to a poorer chance of recovery. Being overweight before treatment begins also increases the risk of serious health conditions. These include high blood pressure, diabetes, and heart problems.

Causes of weight gain during cancer treatment

The following cancer treatments may lead to weight gain:

Chemotherapy. Chemotherapy can lead to weight gain in several ways, including by:

  • Causing the body to hold on to excess fluid, called edema.

  • Causing people to reduce physical activity, usually because of fatigue.

  • Causing nausea that is improved by eating.

  • Triggering intense food cravings.

  • Decreasing a person’s metabolism, which is the rate that the body uses energy.

  • Causing menopause in some women, which decreases the metabolism.

Steroid medications. Doctors prescribe steroids during cancer treatment for several reasons, including:

  • To reduce symptoms of inflammation, such as swelling and pain.

  • To treat nausea.

  • As part of the treatment for the cancer itself.

However, steroids can cause certain side effects, including:

  • An increase in appetite.

  • An increase in fatty tissue (with long-term use), which can increase the size of a person’s abdomen and cause fullness in the neck or face.

  • Weight and muscle mass loss, called wasting.

  • A noticeable increase in weight (with continuous, long-term use).

Hormonal therapy. Hormonal therapy may be used to treat breast, uterine, prostate, and testicular cancers. It involves medicines that decrease the amount of estrogen or progesterone in women and testosterone in men. Decreases in these hormone levels can increase fat, decrease muscle, and lower the metabolism.

Managing weight gain

Relieving side effects is an important part of cancer care and treatment. This is called palliative care, or supportive care. Talk with your health care team about any symptoms you experience and any change in symptoms.

If weight gain becomes a concern, talk with your doctor or a registered dietitian (RD) before starting a diet or changing your eating habits. They can help you find the possible cause and the best way to manage it. An RD can also provide nutritional guidelines or a customized diet plan.

Consider the following ways to address weight gain through diet and physical activity:

  • Eat plenty of fruits, vegetables, and whole grains.

  • Limit fat, sugar, and refined flour.

  • Drink plenty of water.

  • Use healthier cooking methods whenever possible. For example, try steaming instead of frying.

  • Identify everyday eating patterns that lead to overeating and inactivity. Your RD can help you with this.

  • Find physical activities, such as walking or bicycling, that you enjoy. Try strength-building exercises if you have lost muscle. But check with your doctor before starting a new type of exercise or increasing your physical activity.

Managing fluid retention-related weight gain

Call your doctor if you experience any of the following signs of fluid retention:

  • Skin that feels stiff or leaves small indentations after pressing on the swollen area.

  • Swelling of the arms or legs, especially around the ankles and wrists.

  • Rings, wristwatches, bracelets, or shoes that fit tighter than usual.

  • Decreased flexibility in the hands, elbows, wrists, fingers, or legs.

The following tips can help you manage fluid retention:

  • Ask a doctor about prescribing a medication that increases urination to rid the body of excess water. This is called a diuretic.

  • Lower the amount of salt in your diet.

  • Avoid standing for long periods.

  • Elevate your feet as often as possible.

  • Avoid crossing your legs, which restricts blood flow.

  • Weigh yourself at the same time each day and keep track of changes. Bring this log with you to appointments for your health care team to evaluate.

  • Avoid tight clothing and footwear.

  • Ask your health care team if wearing support or compression stockings may help.

Related Resources

Obesity and Cancer

Nutrition Recommendations During and After Cancer Treatment

Side Effects