In November 2007, the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF) published a voluminous report — Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective — for which world experts analyzed 7,000 cancer studies. One of the most significant findings: Excess body fat is consistently linked to an increased cancer risk, specifically for cancer of the esophagus, pancreas, colon and rectum, endometrium, kidneys, and breasts. Adding to the evidence, a study published in The Lancet in February 2008 showed a link between obesity and at least a dozen cancers. Researchers found that an average weight gain of just 33 pounds in men increased the risk of esophageal cancer by 53 percent.
“There's an enzyme machinery in fat cells that leads to the production of hormones like estrogen, which plays an important role in the reproductive cancers,” explains David Schottenfeld, MD, MSc, professor emeritus of epidemiology and internal medicine at the University of Michigan and a member of the medical advisory board for the Prevent Cancer Foundation. The fat cells in an expanded waistline can also cause a state of chronic inflammation. “That smoldering inflammation can lead to the promotion of tumor growth,” says Schottenfeld. Researchers also point to insulin levels as another obesity-related cause of cancer. Bottom line: As the American population grows ever rounder, cancer rates are destined to rise.