Researchers have known for some time that being overweight puts people at an increased risk of certain types of cancer. A recent report from the American Institute for Cancer Research (AICR) shows just how great that risk is.
The report, which looked at the relationship between cancer and risk factors such as poor diet, lack of physical activity, and excess weight, found that more than 100,000 cancers in the United States each year are linked to too much body fat. Approximately 17% of breast cancers are linked to carrying extra weight, AICR researchers estimated.
"The evidence is clear: If people sustain a normal body weight and remain physically active throughout life, it will have a major impact on cancer incidence," said Laurence N. Kolonel, MD, PhD, deputy director of the Cancer Research Center of Hawaii and a member of the expert panel who crunched the numbers.
American Cancer Society researchers were among the first to uncover the connection between being overweight and cancer risk. A 2003 Society study of more than 900,000 men and women found the heaviest men had death rates from all cancers combined that were 52% higher than the rates among normal-weight men. The heaviest women had cancer death rates 62% higher than normal-weight women, the study found.
Why does being overweight make a person more likely to get cancer? Several factors are thought to be at work, says Kolonel. Excess body fat appears to increase the amount of hormones like estrogen circulating in the body, and it can also disrupt how the body processes insulin. Both of those factors have been linked to an increased cancer risk. In addition, Kolonel says, "Being overweight creates low-grade inflammation in the body, and there's a lot of research going on right now that links chronic inflammation to cancer." Reducing your risk - Fortunately, there's a lot you can do to control your risk.
The American Cancer Society recommends balancing calorie intake with physical activity. Eat at least 5 servings of fruit and vegetables every day, choose whole grains over processed grains, and limit red meat. Adults should get at least 30 minutes of moderate or vigorous physical activity 5 days a week or more. Moderate activities include walking, skating, canoeing, or yoga - anything that makes you breathe as hard as you would on a brisk walk. Vigorous activities are those that make you breathe harder and break a sweat, like jogging, running, basketball, or cross-country skiing.
For help with eating right and getting active, check out the American Cancer Society's new online Web site at eatrightgetactive.org. The site has an online food journal so you can track what and how much you eat, and can help you set and track your progress on exercise and diet goals – like eating those 5 servings of fruits and vegetables every day.