How Does Yo-Yo Dieting Impact Cancer Development?

Weight cycling may influence the biological processes that can lead to cancer.

For people waging a daily war with the scale to keep weight off, the practice commonly known as yo-yo dieting can be a frustrating hurdle.

The good news for these people, however, is that weight cycling may not lead to an increased risk of developing cancer. A study by the American Cancer Society published online recently in the American Journal of Epidemiology found that the yo-yo of weight loss and gain is not associated with an increase in the overall cancer risk in men or women, after adjusting for body mass index and other factors.

Furthermore, weight cycling was also not linked to any individual cancer that was examined. These results, according to authors of the study, should encourage people trying to lose weight even if they may regain it.

Prior studies in both animals and humans indicated that weight cycling may impact biological processes that can lead to cancer, including increased T-cell accumulation, stronger inflammatory responses in adipose tissue, and decreased natural killer cell cytotoxicity. The majority of these findings, however, have yet to be replicated, as at least 2 previous studies found no association between weight cycling and cancer.

For the current study, the researchers analyzed weight cycling and cancer in more than 132,000 men and women enrolled in the Cancer Prevention Study II Nutrition Cohort. The study included detailed dietary information from men and women 50 to 74 years of age to evaluate the effect of nutrition on cancer incidence and mortality.

The researchers examined weight cycling and incidence for all cancer types and 15 individual cancers, as more than 25,000 participants developed the disease over the 17 year duration of the study.

"For the millions of Americans struggling to lose weight, the last thing they need to worry about is that if it comes back, they might raise their risk of cancer," said lead researcher Victoria Stevens, PhD. "This study, to our knowledge the largest and most comprehensive to date on the issue, should be reassuring. Our findings suggest that overweight and obese individuals shouldn't let fears about their ability to maintain weight loss keep them from trying to lose weight in the first place."