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Breast Cancer and Weight Changes

Women with breast cancer often complain of weight gain as an undesirable side effect of their treatment. Premenopausal women who receive chemotherapy are at higher risk for weight changes after completing therapy.

Many women who have chemotherapy for breast cancer have reported an average weight gain of about 5 to 8 pounds over a year. Some have reported gaining less, while others have gained as much as 25 pounds.

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What causes weight gain with breast cancer?

Many things contribute to weight gain.

One reason could be premature menopause brought on by chemotherapy. Menopause makes it easier to gain weight because it causes metabolism to slow down. There is also a change in body composition. Your body gains more body fat and loses lean muscle.

A second reason for weight gain during breast cancer treatment is the use of corticosteroids to help with nausea or swelling or to prevent a reaction that can occur with chemotherapy. These types of drugs can cause an increase in your appetite. Steroids are hormonal substances that can also cause an increase in fatty tissue. In addition, they can cause a redistribution of muscle mass from the extremities into the abdominal area as fat. The usual result is a fullness of the neck or face and a big belly. Another side effect of steroid medications is loss of muscle mass. That loss of muscle makes weight gain more apparent.

Some research suggests that weight gain is also related to lack of exercise. The drop in the level of physical activity may be due to the stress, fatigue, nausea, or pain that come with breast cancer treatment.

Weight gain may also be related to intense food cravings. Some women have cravings that typically involve sweets and carbohydrates during chemotherapy. These foods can cause weight gain, especially when they're not eaten in moderation.

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