2.1. Obesity
The WCRF review panel concluded that weight is a factorthat convincingly leads to an increase in breast cancer risk inpostmenopausal women [6,7]. A recent meta-analysis of epidemio-logical studies reported an increased risk of postmenopausal breastcancer and a decreased risk of premenopausal breast cancer associ-ated to increasing body mass index [8]. The underlying mechanismsfor these associations are poorly understood, but the importanceof ethnicity, fat distribution and related specific markers of insulinresistance in the association with premenopausal breast cancer riskhas been suggested [9].