New data from Cancer Research UK predicts that cancer rates will continue to rise over the next 20 years, but rates among women are expected to increase six times faster than those of men. Before you get too down about this news, there is one ray of hope: according to the study, the majority of these cases are preventable by living a healthy lifestyle, maintaining an ideal weight, and getting enough exercise.

Female cancer rates are rising so quickly partly because the number of women who drink alcohol and smoke cigarettes has only recently matched that of men. However, according to the study, published online in the British Journal of Cancer, the biggest reason behind the increase in projected cancer rates is obesity. Many forms of cancer specifically linked to obesity affect only women, including womb cancer, ovarian cancer and postmenopausal breast cancer.

Read: More Women Than Men Are Now Overweight, In Need Of Better Prevention Methods

“Our evidence shows that around a third of the most common cancer cases could be prevented if people were a healthy weight, had a healthier diet and were more active,” Sarah Toule, head of health information at World Cancer Research Fund, who was not involved in the study, told The Independent. “For breast cancer, this would mean preventing around two in five cases.”

The American Cancer Society estimates that around 20 percent of all diagnosed cancers in the U.S. are related to unhealthy lifestyles, and excess body weight contributes to as many as one in every five cancer-related deaths. Though scientists are sure of this link between body fat and cancer, it’s still unclear exactly why it exists. At the moment, doctors think it may be because excess weight affects certain body mechanisms, such as immune system function, hormone levels, and cell growth.

In the United States, there are more obese women than there are obese men, and women also tend to have a higher class of obesity rating. For example, a class 3 obesity rate refers to individuals with a BMI of 40 or higher, also known as morbid obesity. A 2016 study on the prevalence of obesity in America found that women had a 9.9 percent class 3 rate compared to 5.5 percent in men.

Obesity is a largely preventable and reversible health condition, and researchers hope that enlightening the public on the dangers of excess weight could help people lose weight and keep it off.

Source: Smittenaar CR, Peterson KA, Stewart K, Moitt N. Cancer incidence and mortality projections in the UK until 2035. British Journal of Cancer . 2017

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