Although high body mass index (BMI) is an established risk factor for several cancers, it hasn't been clear how long a woman needs to be overweight to elevate her risk. An international team of investigators decided to find out.

The researchers analyzed the records of 74,000 participants who were enrolled in the observational arm of the Women's Health Initiative (WHI). The participants were free of cancer at the beginning of the study and their BMIs had been recorded over several years.

They found that being obese or overweight was associated with greater risk of developing postmenopausal breast cancer, adenocarcinoma of the esophagus, or cancer of the pancreas, colon, kidney, endometrium, ovary, or gallbladder. Moreover, the amount of weight the women carried and the length of time they were overweight during adulthood seemed to play an important role in the risk of developing cancer, especially endometrial cancer.

The findings, which were published Aug. 17, 2016, in PLOS Medicine, indicate that if your BMI is over 25, it may be a good time to consider a weight-loss program. You may be able to lower your cancer risk by reaching a healthy weight and maintaining it.