Being overweight or obese is clearly linked to an overall increased risk of cancer. According to research from the American Cancer Society, excess body weight is thought to be responsible for about 8% of all cancers in the United States, including two of the most common cancers in the United States, breast and colon cancer. Many people exercise to prevent heart disease, but exercise can also play a key role in preventing cancer. as well as about 7% of all cancer deaths.
Also, having too much belly fat (that is, a larger waistline), regardless of body weight, is linked with an increased risk of colon and rectal cancer, and is probably linked to a higher risk of cancers of the pancreas, endometrium, and breast cancer (in women past menopause).
The timing of weight gain might also affect cancer risk. Being overweight during childhood and young adulthood might be more of a risk factor than gaining weight later in life for some cancers. For example, some research suggests that women who are overweight as teenagers (but not those who gain weight as adults) may be at higher risk for developing ovarian cancer before menopause.
Research on how losing weight might lower the risk of developing cancer is limited. Still, there’s growing evidence that weight loss might reduce the risk of breast cancer (after menopause), more aggressive forms of prostate cancer, and possibly other cancers, too.
Some body changes that occur as a result of weight loss suggest it may, indeed, reduce cancer risk. For example, overweight or obese people who intentionally lose weight have reduced levels of certain hormones that are related to cancer risks, such as insulin, estrogens, and androgens.
While we still have much to learn about the link between weight loss and cancer risk, people who are overweight or obese should be encouraged and supported if they try to lose weight. Aside from possibly reducing cancer risk, losing weight can have many other health benefits, such as lowering the risk of heart disease and diabetes. Losing even a small amount of weight has health benefits and is an excellent place to start.