June 26, 2026
Ten percent of new cancer diagnoses in the United States are linked to being overweight or obese, and losing at least 10% of your body weight may be necessary to lessen the adverse effects of obesity and lower the risk, according to a comprehensive review published in JAMA.
The review, coauthored by Kristy Brown, PhD, co-leader of the Obesity, Metabolic Health and Cancer research program at The University of Kansas Cancer Center, summarizes evidence from basic science, clinical trials and populations studies showing how obesity leads to the development of cancer and how that risk may be reduced.
“We have the epidemiological data, we have the mechanistic data and we have the clinical data that show the impact of obesity on outcomes for patients,” said Dr. Brown, also an associate professor of cell biology and physiology at KU Medical Center. “This paper brings all that together and identifies key mechanisms linking obesity to cancer and how interventions that affect these different mechanisms can break that link.”
Dr. Brown’s collaborators on the review were three oncologists, from Memorial Sloan Kettering Cancer Center, Weill Cornell Medicine and Winship Cancer Institute of Emory University.
By the year 2030, nearly 50% of American adults are expected to have obesity, up from 42% in 2020 and 35% in 2010, the paper notes. A dozen cancers are classified as obesity-related by the International Agency for Research on Cancer, including colorectal, endometrial, postmenopausal breast, gallbladder, kidney, liver, esophageal, ovarian, pancreatic, gastric, multiple myeloma and thyroid cancer.
The review describes how excess body fat stimulates cancer development through oxidative stress and DNA damage as well as through inflammation and altered hormone production. It also outlines how obesity impairs the ability of the immune system to recognize and destroy cancer cells, and how obesity can alter the gut microbiome, increasing inflammation and reducing the number of bacteria that suppress tumors.
Moreover, the review explores how weight loss could lessen cancer risk and examines the effects of weight loss treatments including bariatric surgery and GLP-1 drugs such as Wegovy (semaglutide). The authors also consider how much weight reduction might be necessary. “Ten percent has been the benchmark, but I think the data are pointing more toward a need for greater weight loss to show substantial impact on risk reduction,” Dr. Brown said.
In addition to synthesizing research results and identifying areas needing further study, the review also can be helpful to clinicians who can communicate the information to patients, many of whom might not even know about the link between obesity and cancer, Dr. Brown said. “This review gives clinicians a tool to say, ‘There is evidence that obesity is linked to a higher risk of these cancers, and if you want to know more about how that works, we have some data here, and we also have some tools to be able to tackle that.’”
This article originally appeared on the University of Kansas Medical Center's website.