It's the one thing most doctors agree on: If you can do only one thing to lower your lifetime risk, it should be maintaining a healthy weight. Packing too many pounds can increase your breast-cancer chances by 30 to 60 percent, says Carolyn Aldigé, of the Prevent Cancer Foundation. (Particularly worrisome is often-hidden abdominal fat, which can raise your risk by a stand-alone 43 percent.)
See, fat cells don't just sit still; they can pump out extra estrogen, says Karen M. Basen-Engquist, Ph.D., M.P.H., of the University of Texas MD Anderson Cancer Center. So the more fat cells you have, the more estrogen is likely coursing through your body. And the more of that circulating estrogen you have over the course of your life, the higher your breast-cancer risk, says Graham Colditz, M.D., Ph.D., of the Institute for Public Health at the Washington University in St. Louis School of Medicine.
Plus, being overweight or obese means you're providing a host environment for cancer progression, explains Lee W. Jones, Ph.D., of the Duke Cancer Institute. "That's lots of insulin, lots of glucose, lots of inflammation—all of which conspire to speed up cancer-cell growth once a malignancy occurs."
What's a healthy weight? For now, the best measure might be a "normal" body mass index (BMI). It's not a perfect measurement, but it can give you a clue as to whether you're tipping the scale in the wrong direction, says Elisa Port, M.D., of the Dubin Breast Center at the Mount Sinai Medical Center. If you're obese or suspect you're overweight, don't waste any time—start slimming down by following the aforementioned fitness and nutrition advice. And remember, says Colditz, "The best thing you can do for yourself—and your breast-cancer risk—in the next 12 months is to not gain any weight."
