Weight Gain

This section has been reviewed and approved by the PLWC Editorial Board , 02/05

Although it is more common to lose weight during cancer treatment, some people with cancer gain weight. Slight increases in weight during cancer treatment are generally not problematic. However, significant weight gain may affect a person's health and the ability to tolerate treatments.

Weight gain is an especially important health issue for people living with breast cancer, as over half of women experience weight gain during treatment. Reports have shown that weight gain is linked to a poorer prognosis (chance of recovery). Being overweight before treatment begins also increases the risk of serious health conditions, such as high blood pressure, diabetes, and cardiovascular disease.


The following cancer treatments may produce symptoms that lead to weight gain:


  • Some chemotherapy causes the body to retain (hold on) to excess fluid in cells and tissues, called edema.
  • A decrease in physical activity, usually from fatigue, can cause people to exercise less and leads to weight gain.
  • Chemotherapy can increase hunger (especially for high-fat foods) and can trigger intense food cravings.
  • Chemotherapy has been shown to decrease metabolism (the rate that energy is used), which can cause weight gain.
  • Chemotherapy can cause menopause in some women, which is associated with changes in metabolism that can increase the likelihood of weight gain.

Steroid medications

Steroids are hormonal substances that are used in cancer treatment. They can cause an increase in fatty issue, resulting in a big belly and fullness in the neck or face. Steroids can also cause peripheral wasting (the loss of muscle mass). A noticeable increase in weight usually only happens when people have been taking steroids continuously for many weeks.

Hormone therapy

Hormone therapy for the treatment of breast, uterine, prostate, and testicular cancers involves medications that decrease the amount of estrogen or progesterone in women and testosterone in men. Hormone therapy can increase body mass from fat, decrease body mass from muscle, and change how food is metabolized, resulting in weight gain.

Managing weight gain

If gaining weight becomes a concern, consult a doctor or registered dietitian (RD) before starting a diet or changing eating habits. They can help discover the possible cause of the weight gain and find the best way to manage it. In addition, an RD can provide nutritional guidelines or a customized diet plan.

Ways to manage diet and physical activity include the following:

  • Eat plenty of fruits, vegetables, breads, and cereals.
  • Limit fats, simple sugars, and refined flour.
  • Drink plenty of water.
  • Evaluate everyday eating habits and try to identify behavior patterns that lead to overeating and inactivity.
  • Check with a doctor about increasing the amount of exercise.
  • Do strength-building exercises for the arms and shoulders if muscle mass has been lost.

Signs of fluid retention

It is important to immediately call a doctor if there are any of the following signs of fluid retention:

  • Skin that feels stiff (small indentations left on the skin after pressing on the swollen area)
  • Swelling around ankles and wrists
  • Rings, wristwatches, bracelets, or shoes that fit tighter than usual
  • Decreased flexibility in hands, elbows, wrists, fingers, or legs

The following tips can help a person manage fluid retention:

  • Ask a doctor about prescribing a diuretic medication to rid the body of excess water.
  • Lower the amount of salt in the diet.
  • Avoid standing for long periods and elevate feet as often as possible.
  • Avoid crossing the legs, which restricts blood flow.
  • Monitor body weight daily.
  • Avoid tight clothing.

More Information

PLWC Feature: Exercise and Cancer 

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