How Your Weight Affects Your Risk of Breast Cancer

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Managing weight is a challenge for most people in the US. In fact, according to the Centers for Disease Control and Prevention (CDC), more than 70% of American adults are overweight.

This puts them at higher risk for serious conditions including diabetes, heart disease, and some types of cancer. For women, being overweight or obese after menopause increases the risk of breast cancer.

Having more fat tissue can increase your chance of getting breast cancer by raising estrogen levels. Also, women who are overweight tend to have higher levels of insulin, another hormone. Higher insulin levels have also been linked to some cancers, including breast cancer.

But the connection between weight and breast cancer risk is complicated. Studies suggest the risk appears to be increased for women who gained weight as an adult but may not be increased among those who have been overweight since childhood. Also, having extra fat in the waist area may raise risk more than having extra fat in the hips and thighs.

And even though it’s been established that gaining weight raises your risk, it’s not clear whether losing weight reduces your risk. This turns out to be a tough question for scientists to answer, mainly because very few people actually lose weight during adulthood, and those who do lose weight don't usually keep it off over a long period of time. So it is difficult to find a large enough group of people to study.

We do know that avoiding weight gain is helpful, whether you are overweight now or not. If you’re carrying extra pounds, losing as little as 5%-10% of your weight improves your overall health. A good goal for most overweight women is to drop half a pound per week for 6 months. What's more, exercise can also lower breast cancer risk above and beyond the impact it can have on losing weight. Many studies have found that exercise is a breast-healthy habit. As little as 75 to 150 minutes of brisk walking each week has been shown to lower risk. Ramping up your exercise routine even more may lower your breast cancer risk even further.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.


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