What’s the link between obesity and colorectal cancer?
Obesity is a complex disease characterized by an excessive amount of body fat. It’s important to understand that obesity is not just about weight—it is a medical condition that can have serious health implications. Obesity is linked to many cancers, including endometrial, liver, kidney, pancreatic and breast cancers (for breast cancer, this is especially in post-menopausal women). Perhaps most notably, research shows a strong link between obesity and colorectal cancer.
Here’s what you should know about obesity and colorectal cancer risk—and what you can do about it:
What is obesity?
Obesity is a chronic disease characterized by excessive body fat. It can increase the risk of heart disease, diabetes and some cancers. In the U.S., 1 in 5 children and 2 in 5 adults have obesity.1 Obesity is influenced by many factors ranging from health behaviors and stress to people’s genetics and environments.
What is colorectal cancer?
Colorectal cancer is cancer that begins in the colon or rectum (everyone has a colon and rectum unless they have been surgically removed). This cancer can often be prevented with a colonoscopy, where your doctor can find and remove polyps (grape-like growths on the wall of the large intestine, which is part of the colon) before they become cancerous. If the polyps have already become cancer, colonoscopies can also detect colorectal cancer in its early stages. There are also many other screening options available, including at-home tests, that can detect the disease early when the cancer is small and hasn’t spread.
How does obesity increase the risk of colorectal cancer?
According to the National Cancer Institute, compared with people without obesity or overweight, colorectal cancer is 1.3x as likely to occur in people who have obesity. There are many possible reasons for this increased risk:
- Carrying excess weight raises the levels of insulin and related hormones in the blood, which can promote cancer growth. Excess weight is also known to promote inflammation, which can contribute to the growth of cancer.2
- Obesity is associated with type 2 diabetes—another risk factor for colorectal cancer. A 2023 study found that people who have diabetes have a 47% higher risk of developing colorectal cancer compared to those without diabetes.
How can I reduce my risk of obesity and colorectal cancer?
There are many steps you can take to reduce your risk of both obesity and colorectal cancer:
- Eat a plant-based diet: Eating a balanced diet rich in fruits, vegetables, whole grains and lean proteins (such as chicken, fish or eggs) can help you maintain a healthy weight and reduce your cancer risk. Limiting red and processed meats is also beneficial—both are strongly linked to colorectal cancer.
- Be physically active: Physical activity is linked to a lower risk of colorectal cancer. Not only can physical activity help in maintaining a healthy weight, but adding exercise to your routine can also reduce stress, increase energy and boost your immune system.
- Avoid tobacco and alcohol: Smoking and excessive alcohol consumption are risk factors for many cancers, including colorectal cancer. It’s best to never start using tobacco, but if you do use tobacco products, it’s never too late to quit—call 1-800-QUIT-NOW for help. Avoiding alcohol completely is best when it comes to reducing your cancer risk as no amount is considered “safe.” For those who do drink alcohol and stop drinking, or those who once overindulged but no longer drink, your cancer risk will decline over time.
- Get screened for colorectal cancer: Routine screenings for colorectal cancer can help find precancerous polyps or detect the disease early when it is in its earliest, most treatable stages. If you are at average risk, screening should begin at age 45. There are many screening options available—including at-home options. Talk to your health care provider about which one is right for you.
By understanding the link between obesity and colorectal cancer and taking proactive steps to check your health, you can reduce your risk and improve your overall well-being. Remember, having a healthy lifestyle is a powerful tool in cancer prevention. Learn more about colorectal cancer prevention and early detection at preventcancer.org/colorectal.
1https://www.cdc.gov/obesity/risk-factors/risk-factors.html
2https://www.foxchase.org/blog/diet-obesity-and-colon-cancer-learn-risks