The link between cancer and body weight is undeniable: a staggering 1 in 5 cancer deaths in the United States is related to excess body weight. Our understanding of the exact relationship between being overweight and the risk of cancer is still somewhat limited, but mounting evidence indicates that cancer can be among the most serious health complications made worse by excess weight.
Excess Body Weight and Cancer Risk
Being obese or overweight increases the likelihood of developing several different types of cancers. Just some of these cancers are:
- Colon and rectum
According to a 2007 study, about 4 percent of new cases of cancer in men and 7 percent of new cases in women were due to obesity. Furthermore, it is estimated that, if current obesity trends keep up, obesity will lead to 500,000 more cases of cancer by 2030.
Among men, a high BMI is strongly linked to instances of colorectal cancer. Kidney cancer risk is elevated in both men and women who are overweight. The link between breast cancer and obesity is still not well understood, however, obesity has been indicated to increase the risk of breast cancer after menopause.
How Does Excess Body Weight Increase Cancer Risk?
It is difficult to cite one particular, direct process by which excess body weight increases cancer risk. However, some possible factors that have been suggested include:
- Excess body weight causes an increase in hormone production in the body. Certain hormones, like estrogen and insulin, are associated with some forms of cancer when they are found in high levels.
- Obese people often experience inflammation, which can increase their risk of cancer.
- Obesity may impact some factors that regulate cell division, including an insulin-like growth factor-1 (IGF-1).
- Being overweight or obese may weaken the immune system, which can increase the likelihood of cancer development.
Will Losing Weight Help Reduce Cancer Risk?
Clearly, being overweight increases a person’s likelihood of developing cancer. However, does it work the other way around, meaning, can losing weight decrease a person’s likelihood of cancer? Research on this topic is limited; however, studies suggest that reducing cancer risk may be among the many health benefits of losing excess body weight. A 2011 study indicated that, upon losing weight either through diet and exercise or bariatric surgery, test subjects saw a decrease in cancer incidence and levels of circulating cancer biomarkers.
According to the National Cancer Institute, even small reductions in weight can make a profound impact upon cancer rates. If every adult decreased their BMI by just 1 percent, or about 2.2 pounds for adults of average weight, 100,000 new cases of cancer could be avoided in the future.
Being overweight or obese can lead to several health complications, and cancer is no exception. Considering that 68 percent of U.S. adults age 20 years and older are overweight or obese, cancer rates will likely continue to rise. However, committing to weight loss may be a step toward a cancer-free future for those at risk.