Right now two-thirds of adults in America are obese and among children, the figure has reached over 10%.
Obesity is scientifically documented to increase the risk for many cancers including esophagus, kidney, colon, thyroid, pancreas, and more. It is alleged that by 2030 the existing trends linking obesity to cancers will reach an additional five hundred thousand cases annually in the United States alone. If each adult just reduced their BMI by 1%, which would roughly equal 2.2 pounds, it would prevent the increase mentioned above in cancer rates by 2030, and more than that, it would actually help avoid 100,000 new cases of cancer.
There are many mechanisms which explain the link between cancer and obesity. The first is the excess fatty tissue which creates excess amounts of estrogen. This has been linked to breast cancers and endometrial cancers. The second is the high level of insulin among obese patients. The increased insulin levels in the blood promotes the development of different tumors. The third is that the fat cells actually produce hormones in the body called adipokines which will either inhibit cell growth or promote it. Leptin, a hormone that is found in excess among obese people, promotes cell proliferation but adiponectin, which is not nearly as abundant among obese people, has anti-proliferative effects.