The rate of obesity increased faster among cancer survivors than the general population in the 14 years between 1997 and 2014, according to a study published in the Journal of Clinical Oncology.

“We knew that obesity rates have been increasing in the general population, but we did not know if and how these rates were changing among cancer survivors,” Dr. Heather Greenlee, an epidemiologist at Mailman School of Public Health of Columbia University and the first author of the study, said in a news release.

Cancer survivors may be at higher risk for obesity because some cancer treatments cause weight gain. Additionally, some cancer survivors gain weight as a result of becoming less physically active after diagnosis. Some scientists even say obesity itself may be causing certain types of cancer such as colorectal and breast cancer.

In the study “Trends in Obesity Prevalence in Adults With a History of Cancer: Results From the US National Health Interview Survey, 1997 to 2014,” researchers analyzed data from more than half a million people ages 18-85 who participated in annual National Health Interview Surveys between 1997 and 2014. More than 30,000 cancer survivors responded.

Researchers found that the prevalence of obesity among the subjects increased significantly among cancer survivors and the general populations. However, obesity rates were higher among survivors of colorectal and breast cancers, and among non-Hispanic black survivors.

Among colorectal cancer survivors, increasing rates of obesity were greatest for women ages 18-44 years, men ages 65-85, non-Hispanic black survivors, women 2-9 years from diagnosis, and men 10 or more years from diagnosis.

Among female breast cancer survivors, the highest increases in obesity were seen in women ages 18-44, non-Hispanic white women, and those 1 year or less from time of diagnosis.

Class 1 obesity (BMI between 30 and 35) was more common among female survivors of cancer than women who never had cancer.

“It is important to reverse the growing rate of obesity in cancer survivors,” Greenlee said. “To do so, cancer survivors need access to qualified health professionals who can adequately counsel them on appropriate diet, physical activity and weight management goals. Patients likely need much more than a booklet outlining specific goals; patients likely need proven programs to help them achieve and maintain their goals. A major challenge in this area is that many health insurance plans do not cover the cost of these services.”