Carrying extra weight is a risk factor for developing breast cancer. But it's not been clear how the timing of weight gain affects this risk. Evidence is mounting, though, and it's now believed that weight gain in adult life is more predictive of breast cancer risk than absolute body weight.

A new study, published in December's International Journal of Cancer, reveals a link between gaining weight in adulthood and an increased risk of breast cancer after menopause.

"We did find some suggestion that weight gain during the 30s and 40s, weight gain since a woman's first pregnancy and weight gain since menopause, especially for women with a longer time since menopause, may all be of importance in relation to postmenopausal breast cancer risk," report the researchers who followed 1,166 women with breast cancer and 2,105 without the disease.

A 70 percent increased risk was found among postmenopausal women who gained more than 60 pounds between age 20 and the onset of menopause. This was in comparison to women who gained less than 20 pounds during the same period of time. Overall, there was a four percent increase in breast cancer risk for each 11-pound increase in adult weight.