Researchers tracked 87,000 women for 26 years, and found that if post-menopausal women lost at least 22 pounds, their breast cancer risk was reduced by 40 percent. If they kept the weight off for at least four years, their risk was cut by an additional 60 percent.
According to lead study author A. Heather Eliassen, an epidemiologist at Brigham and Women's Hospital and Harvard Medical School, weight is a risk factor of breast cancer that women can control.
Researchers also found that women who gained 55 pounds or more after age 18 had a 45 percent greater risk of breast cancer, while gaining 22 pounds or more after menopause led to a 20 percent increase in risk. Among the women who gained 55 pounds or more after age 18, those who did not use hormone replacement therapy had a 98 percent increase in breast cancer risk, while those who used the therapy had a 20 percent increase in risk.
Eliassen's study was the first to examine the effects of post-menopausal weight loss, though previous studies had established that fat produces estrogen, which promotes tumor growth in some kinds of breast cancer.
Eating food high in refined sugars and grains can increase insulin in the bloodstream, which increases body fat production and the risk of obesity. Other risk factors for the disease include smoking and alcohol consumption.
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