Breast cancer risk runs high in the post-menopausal years, and various prevention strategies have been suggested, including those keeping your body weight in check. But how you actually do it seems to make a difference as well.
Obesity and physical inactivity (both prevalent in the Western world) is actually thought to contribute to about 15% of post-menopausal breast cancer. As this is definitely a substantial number, the concern about physical well-being of women post-menopause seems to be legitimate.
Sex Hormones and Physical Exercise 2 (SHAPE-2) trial, conducted in the University Medical Centre Utrecht in the Netherlands, has recently reported that exercise, particularly strength training, may more beneficial in keeping sex hormones at normal levels than diet alone.
Increased levels of estrogens and androgens, as well as shortage of sex hormone-binding globulin (SHBG), which helps to control the level of hormones in the blood, are known risk factors for breast cancer. One of the main culprits of hormone overproduction after menopause is fat tissue, which participates in the conversion of androgens to estrogens. Therefore averting obesity should help control the risk of breast cancer too.
Curiously enough, the initial SHAPE trial was unable to confirm this idea with certainty, but some positive effects were observed in women who lost the most weight. Encouraged by this finding, the researchers designed the next study to measure not only the relative weight loss, but compare the different effects of how it is achieved, and assess the overall lost fat content.
Perhaps unsurprisingly, women enrolled in the “exercise” group (including endurance and strength training) lost more fat that those who only kept a hypocaloric diet. A 6- 7% of exercise-driven weight loss lead to a leaner form and better physical fitness which were maintained for longer, as well as larger effects on the blood hormone composition.
“These findings support the hypothesis that the greater loss of body fat induced by exercise compared with diet largely mediates the effects of physical activity on sex hormones”. Moreover, as the researchers suspect, exercise might be operating through an additional, non-fat related pathway that helps to improve the levels of sex hormones even further.
SHAPE-2 study may be held as major milestone in understanding the role of body weight in controlling the risk of breast cancer, and further underlines the importance of physical activity in keeping good health after the menopause.
Written by Eglė Marija Ramanauskaitė