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Does being overweight affect breast cancer risk?

Dropping those extra pounds may lower your chances of becoming sick, “Today” contributor Dr. Judith Reichman advises.
/ Source: TODAY

Q: I'm 52 years old and overweight. I'm “scared to death” of breast cancer. Will losing weight decrease my risk of getting it?

A: Yes. New data obtained from the well-known Nurses’ Health Study shows that weight loss after menopause does indeed decrease the risk of breast cancer. This study began in 1976, at which time it enrolled over 120,000 female, married, registered nurses who were, at the time, between the ages of 30 and 55. These women have been followed ever since, receiving mailed questionnaires two times a year (and the majority of the nurses respond) that request information on their lifestyle factors, including breast cancer risk factors.

The breast cancer portion of the study, published in the Journal of the American Medical Association, included almost 50,000 of these women (some of who were followed for as long as 24 years) who noted their weight changes since menopause. It found that being overweight increased their risk of breast cancer. Specifically, women who gained 55 pounds or more since age 18 were 1.5 times more likely to get breast cancer compared to woman who did not gain weight from their late teens. The women who stayed at the same weight from age 18 and then gained 22 pounds or more after menopause had an 18 percent increased risk of breast cancer when compared to the “never” weight gainers.

Now for the good news: Those women who lost 22 pounds or more after menopause (it didn't matter if they gained weight before or after menopause) had a 57 percent lower risk of breast cancer than the “weight gainers” who maintained their status quo. Loss of weight means less fat, and fat has its own hormone effect: it converts hormones produced by the adrenal glands into estrogens. The more fat, the more estrogen in a woman’s body. Is the “estrogenized environment” that’s associated with excess fat the culprit? We’re not sure. Studies have also demonstrated that when estrogen is given as hormone therapy without concomitant progestin it does not appear to increase breast cancer risk. A simple hormone (or one hormone) explanation may not give us the answer.

You already know that by losing weight you can decrease blood sugar (and risk of type 2 diabetes), improve the ratio of good and bad cholesterol and lessen hypertension (and risk of heart attack and stroke). You’ll certainly look better and feel better. You can add to these “thinning benefits” the fact that you will significantly decrease your risk of invasive breast cancer.

Dr. Reichman's Bottom Line: Weight loss, even if you wait until after menopause, can lower the risk of breast cancer. It's never too late to lose weight.

Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of .

PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.