(AlignLife) Obesity is linked with a huge increase in risk of breast cancer according to several recent studies and the main culprit appears to be leptin, a hormone secreted by fat cells. This finding applies to women of all ages, not just those who are postmenopausal. A woman's lipid profile and levels of unbalanced estrogen in conjunction with high body mass index have been shown as additional factors determining whether she gets breast cancer and how deadly it will be.