Why do some women with breast cancer gain weight?

Many women experience a significant amount of weight gain during their treatment for breast cancer. Although the reasons for this weight gain are largely unknown, it may be a result of several factors such as frequent snacking on energy dense foods to prevent nausea, reduced motivation to eat a nutritious diet, reduced activity levels, medications such as chemotherapy and steroids, or the onset of menopause. Your extra weight may hang around and increase after your treatment if you also take hormonal therapy (tamoxifen or an aromatase inhibitor).

Weight gain can occur with and without chemotherapy. The shock of a diagnosis, the disruption of your life, getting through and beyond surgery and radiation, the strain of relationships at home and at work, financial stress, and less physical activity all contribute to weight gain. Many women believe that hormonal therapy makes them gain weight and makes it difficult to lose weight. However, scientific research has shown that women taking a placebo (a sugar pill) are just as likely to gain weight as women taking tamoxifen. However, it is unknown whether the newer therapies such as Aromatase Inhibitors cause significant weight gain at this stage.  

Many women also believe that gaining weight is due to menopause; however, most women gain weight well before the onset of menopause. For instance, Australian women have been shown to gain an average of 6.3 kilograms during their adult life, the majority of which is between the ages of 20 and 50.

If you've gained weight, you probably want to know why. Perhaps you are less physically active but eating as much as (or more than) before. And you may need FEWER calories to maintain the same weight because of menopausal changes in your overall metabolism.Losing weight becomes much harder as we grow older, but it can still be done with exercise and very careful changes in your diet. Be nice to yourself; don't punish yourself.