Even moderate weight loss can contribute to a significant drop in estrogen levels associated with an increased risk of breast cancer in postmenopausal women, according to a study published in the Journal of Clinical Oncology. ‘
Our research suggests that a loss of 5 percent. or more body weight can reduce the risk of the most common estrogen-sensitive breast cancer by 25-50 percent. – says Dr. Anne McTiernan of the Cancer Research Center Fred Hutchinson in Seattle (USA).
However, these conclusions only apply to overweight or obese women who are not using hormone replacement therapy. The 439 women aged 50 to 75 who met these criteria were divided into four groups: the first participated in an exercise program (mainly fast walking), the second was on a diet, the third – a diet combined with exercise, and the fourth remained with the usual lifestyle. The goal was to lose around 10 percent. body weight, which was achieved by the ladies in the second and third groups.
Scientists measured the effects of diet and exercise on the levels of certain sex hormones: estroge (estrone, estradiol and free estradiol), testosterone (total and free), androstenedione, and the sex hormone binding protein SHBG, high levels of which are associated with a lower risk of breast cancer.
The greatest difference between the baseline and end levels of hormones was observed in women who combined diet and exercise. The level of estrone decreased by an average of 11%, estradiol – by 20%, free estradiol – by 26%, free testosterone – by 15,6%, and the concentration of SHBG increased by almost 26%. In the case of women on diet alone, the results were several percentage points lower.
Epidemiological studies have long linked obesity with an increased susceptibility to breast cancer in postmenopausal women. During this period of life, adipose tissue is more involved in the synthesis of sex hormones and contributes to maintaining an elevated level of estrogens.