Findings of a new study indicate that more weight is gained by survivors of breast cancer with a family history of the disease than their counterparts without cancer. Study researchers point towards a relationship between weight gain and treatment.

What makes the findings even more worrisome is the evidence that survivors who gain weight are highly likely to be impacted by cancer again.

“The breast cancer survivors gained more weight, significantly more weight, in the four year follow-up. We actually found that the women treated with chemotherapy were twice as likely to gain this weight compared to the cancer-free women [during] the same time”, said Amy Gross, a Ph.D candidate at the Johns Hopkins Bloomberg School of Public Health.

Gross also authored the paper published in Cancer Epidemiology, Biomarkers & Prevention, revealing that chemotherapy treatment in women with breast cancer doubled their chances to gain weight compared to the cancer-free women during the same time.

Experts already knew that breast cancer patients and survivors gained weight, but they didn’t have an explanation until now about the cause. Some theorized that breast cancer patients or survivors lack motivation to go to work and start eating unhealthy food to get a good feeling, leading them to gain weight.

However, the new research suggests that chemotherapy increases inflammation and makes people insulin-resistant. This alters metabolism and make the person gain weight. The study showed that breast cancer survivors gained an average of 3.6 pounds more weight than women without cancer within four years.