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Breast Cancer Treatment and Weight Changes

Your weight might change when you get treated for breast cancer. Most women gain pounds, but others lose some.

Here are common reasons why, along with nutrition and exercise tips.

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What Might Cause Me to Gain Weight?

Many things can play a role.

Chemotherapy can bring on premature menopause. And with it comes a slowing of the metabolism. That makes it harder to keep weight off. Menopause also causes you to gain more body fat and lose lean muscle.

It’s common for women who have chemotherapy to gain about 5 to 14 pounds over a year. Some gain less, while others put on as many as 25 pounds.

Another reason for weight gain is the use of corticosteroids. These medications help with nausea and swelling, or to stop reactions to chemotherapy. These drugs can boost your appetite. Corticosteroids are hormones that can also cause an increase in fatty tissue. They can make you lose muscle mass in your arms and legs, and gain belly fat, too. You may also have a fullness of the neck or face. Loss of muscle makes weight gain more apparent.

Women treated with steroids may also put on pounds, but the weight gain is usually seen only after weeks of continuous use.

Some research suggests that weight gain is also related to lack of exercise. When you get your cancer treatment, it’s common to feel stress and have some fatigue, nausea, or pain. That can lead to a drop in how much physical activity you get.

Weight gain may also be related to intense food cravings. Some women crave sweets and carbohydrates during chemotherapy. Too much of these foods can lead to added pounds.

Do Other Breast Cancer Medications Cause Weight Gain?

Hormone therapy is another treatment that can cause it. This treatment lowers the amount of estrogen and progesterone in women and the amount testosterone in men. It tends to cause an increase in body fat, too. At the same time, there's a decrease in muscle mass and a change in the way your body converts food into energy.

Many women taking tamoxifen have felt the drug was responsible for their weight gain. So far, though, no conclusive studies have shown a relationship between this hormone and the gains.

Weight gain is not typical in women who've undergone surgery alone, or women who've had surgery followed by radiation alone.

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