Many of you who have heard me talk over the last few years have heard me say that the best way to prevent breast cancer and decrease recurrence is the combination of exercise and maintaining a healthy weight. I always feel a bit guilty telling women to lose weight, because I know first-hand how hard it is! Nonetheless, it keeps coming up in the research and there is no question in my mind that by tackling the obesity epidemic in our country we will decrease breast cancer risk.

The most recent evidence comes from the Nutrition and Exercise for Women study, the first randomized controlled trial to test the effects of weight loss and exercise on sex hormones that are biomarkers for breast cancer risk.

The study enrolled 439 overweight postmenopausal women who participated in less than 100 minutes of exercise a week. They were divided into four groups: a calorie-reduced diet group, an aerobic exercise group, an aerobic exercise and calorie-reduced diet group, and a control group.

The goal for the women on the reduced diet was a 10 percent reduction in body weight by six months that was maintained through the 12-month trial. The goal for the women who exercised was 45 minutes or more of moderate-to-vigorous aerobic exercise (consisting primarily of brisk walking) five days a week. The women in the control group were asked not to change their diet or exercise habits during the course of the study.

At the beginning and at the end of the study, the researchers measured the blood levels of the sex hormones estrone, estradiol, free estradiol, total testosterone, free testosterone, and adrostenedione along with the level of sex hormone-binding globulin (SHBG, which reduces the hormones bioactivity). High levels of these sex hormones have been shown to be associated with breast cancer risk.

The study found that the women who lost weight, with or without exercise, had the largest decrease in their levels of estrone estradiol, free estradiol and free testosterone and increased in their level of SHBG. Based on past studies, these findings suggest that the decrease in these sex hormones reduced these womens breast cancer risk by as much as 22 percent. (This reduction in hormone levels helps explain why weight loss after a breast cancer diagnosis also appears to reduce the risk of recurrence.)

Why do I think this study is important? At every talk I give, someone asks about a recent article they read or advertisement they saw that suggests that eating a certain food be it blueberries, pomegranates, or coconut water will reduce their breast cancer risk. It is much less common for me to get a question about weight loss. But what the research is telling us is this: the best thing you can do to reduce your breast cancer risk is reduce the calories you eat and get off of the couch and out of your slippers and into your sneakers and on the streets.

As much as we would like a magic food to prevent breast cancer, it is weight that is critical as well as exercise! Especially when we are postmenopausal, we need to get moving!

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12 Responses to Weight Loss: The Key to Breast Cancer Risk Reduction

  1. Jonathan says:

    Nice to see this empowering information; that women can do something good for their overall general health that will also lower breast cancer risk. I personally have always thought that a lower level of estrogen resulting from a healthful diet and physical activity was the link between lifestyle and many diseases. Especially since HRT raises the same disease risks that obesity does.

  2. Catherine says:

    The oncologist once told me to start burning off that estrogen. That, to me, was highly motivating in terms of getting moving.

  3. Joy Maheu says:

    Hi Dr. Love — I saw you on ‘Oprah’ many years ago and bought your wonderful book as a result. I only recently discovered your blog and just read about your health challenge. I saw this article online yesterday about a very encouraging leukemia treatment and wanted to make sure you saw it:

    Also, I presume you know about the nutrition-based Gerson Therapy. I have a friend in San Diego who helped her mom survive breast cancer 20 years ago with only surgery and Gerson Therapy. Having been in the profession over 30 years, she’s a genius (literally) at holistic medicine, a gourmet organic chef and, like you, a *very* caring individual. I’m sure she’d do whatever she could to empower and support your health journey. If you want to connect with her, feel free to email me.

    Continued success to you, and Thank You for all the great work you and your awesome team do!

    Joy Maheu

  4. Thin&StillGotBC says:

    What about all of us who are not overweight and still got breast cancer?

    I am tired of hearing about all the things to do to lower your risk, because I exercised, ate right, didn’t smoke, was a healthy weight, etc. and got breast cancer anyway.

    The emphasis on “reducing risk” ignores that most women — isn’t it about 70%? do not have any risk factors.

    Quit the emphasis on individual actions (30%) and let’s hear more about actions to reduce environmental risk (70%).

  5. mcham6 says:

    Thin&stillgotbc, I couldn’t agree with you more. I too got bc and exercised daily, ate right, was not overweight,etc. I am so tired of hearing that it must be something we as women, are doing to increase our risks. Maybe it has nothing to do with diet, but environment. But it makes women who have not received a diagnosis yet feel safer if they think they have control by eating right and losing weight.

  6. Anony says:

    About half of breast cancers are attributable to age of first birth, postmenopausal weight, and use of HRT, according to epidemiologist Anthony Miller. 5-10% are attributable to faulty genes. Science is now uncovering clues about more recently investigated endogenous factors like breast density after menopause. The environment may be involved in some cases of breast cancer, but it’s not 70%.

  7. Amy Hill says:

    I have heard so much about maintaining a healthy weight to decrease the risk of BC. As a 5 year survivor I want to do all I can to decrease my risk of reoccurence. HOWEVER – I have spent the last 5 YEARS trying to lose the 35 lbs I gained during treatment (probably from the mass quantities of steriods as I was eating very little due to loss of taste). I have lost 20 lbs, struggled to keep it off, and am still trying to lose the last 15 lbs. I have counted points, weighed everything that went into my mouth, have numerous spreadsheets, done low carb, low sugar, 400 calories/meal, walked an hour a day 6-7 days a week, swum laps for an hour a day 4-5 days a week, treadmill, bike, weights, and the list goes on and on! If you’re going to tell us to lose weight, please help us figure out how to do it, bc the traditional methods aren’t working. Oh and did I mention I also have tried RX diet drugs as well to no avail. Ugggggg…so frustrated!!!!!!!!

  8. Mark R. Nelson says:

    The risk of cancer as well as other dangerous diseases is very high in excessively overweight group of people. However, the truth is these people will find it difficult to lose weight by exercising at home. My advice is you should join a water aerobics class. I’m a member of a big heathclub in my region and it’s great fun. My instructor even shares her great experience for losing weight here: water aerobics equipment

  9. Sonja Christopher says:

    I, too, “…exercised, ate right, didn’t smoke, was a healthy weight, etc. and got breast cancer anyway”. However, at my HMO’s insistence, did HRT and was diagnosed with invasive breast cancer approx. 11 years later. HRT was, I know, the cause of my breast cancer.

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  11. Maria says:

    I couldn’t agree with you more on this “it is weight that is critical as well as exercise”. Skipping meals or spending the whole day in the gym is definitely not the way out for overweight women. I have seen many women who look pale and weak after they tried to lose weight. Losing weight should go with maintaining good health.

  12. Janeth Demarsico says:

    Leukemia is a treatable disease. Most treatments involve chemotherapy, medical radiation therapy, or hormone treatments. The rate of cure depends on the type of leukemia as well as the age of the patient. Children are more likely to be permanently cured than adults. Even when a complete cure is unlikely, most people with a chronic leukemia and many people with an acute leukemia can be successfully treated for years…;;.


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