Lead author of the study, Victoria Stevens, Ph.D., and colleagues examined whether adulthood weight gain or weight cycling increased a postmenopausal woman’s risk for cancer, independent of body mass index (BMI). Weight cycling is defined as the number of times a woman purposefully lost 10 pounds or more and then later regained the weight. Also known as “yo-yo” dieting, weight cycling had previously been thought to increase the amount of fat mass relative to lean body mass.
According to Stevens, “Fat tissue is the major source of circulating estrogen in postmenopausal, and estrogen is also known to promote the development of endometrial cancer. Therefore, our hypothesis involves the idea that weight cycling could be associated with cancer risk since women engaging in this behavior have a higher proportion of fat than women with a stable weight.
The study investigators accumulated data from over 38,000 women with good uterine health and who provided information on weight history and weight cycling on a 1992 questionnaire. Between the years of 1992 and 2007, 560 women reported being diagnosed with endometrial cancer.
The researchers claim that the results indicate an almost fourfold increase in endometrial cancer risk for women who had gained 61 pounds or more during that period, compared with women who had little weight fluctuation. After adjusting for baseline BMI, the researchers found a twofold increase in endometrial cancer risk.
After adjusting for BMI, the researchers also found no clear association between weight cycling and endometrial cancer risk. According to Stevens, “Weight gain during adulthood may increase risk for endometrial cancer in postmenopausal women, but weight cycling, which results from unsuccessful attempts to lose weight does not increase the risk for this cancer.”
Stevens adds that future research should focus on whether the timing of weight gain and weight cycling during certain periods of adulthood, such as comparing early adulthood versus middle age, influences the risk for endometrial cancer and if weight loss can lower this risk.
The researchers conclude that weight gain during adulthood should be avoided as much as possible to reduce risk for endometrial cancer. Women who have gained weight through adulthood or are overweight or obese should continue to lose the extra pounds even if most weight loss won’t be sustained.