Colorectal cancer is one of the top causes of cancer-related deaths around the world. While age and family history are well-known risk factors, researchers now have strong evidence that obesity plays a major role in increasing the chances of developing this disease.
As obesity rates continue to rise globally, understanding this connection has become more important than ever for preventing colorectal cancer and catching it early.
Obesity isn’t just about carrying extra weight. It affects the body’s hormones, immune system, and how cells function. According to the World Health Organization, obesity has nearly tripled since 1975.
In 2023 alone, more than 650 million adults worldwide were classified as obese. This dramatic increase has had serious consequences, including a higher risk of many types of cancer—especially colorectal cancer.
Studies show that people who are obese have a 30% to 50% higher risk of getting colorectal cancer compared to people with a healthy weight. This is partly because fat tissue, especially around the stomach, releases chemicals that cause long-term inflammation.
It also affects how the body uses insulin and other growth signals. These changes can encourage the growth of abnormal cells in the colon and rectum, which may eventually turn into cancer.
Dr. Maria Thompson, an expert in cancer and metabolism, explains it simply: “Obesity creates a body environment where cancer can grow more easily. That’s why keeping a healthy weight is so important in preventing colorectal cancer.”
Interestingly, where fat is stored on the body matters more than how much fat you have overall. Fat stored in the belly—known as central obesity—is especially dangerous. It’s often measured by waist size or waist-to-hip ratio.
A major study published by the JAMA Network in 2025 found that central obesity might be responsible for up to one-quarter of colorectal cancer cases in men. This means that even people who are not considered obese by body mass index (BMI) might still be at risk if they carry too much fat around their midsection.
So, what can be done?
Lifestyle changes are key. Research shows that eating less red and processed meat—and eating more fiber-rich foods like fruits, vegetables, and whole grains—can lower the risk of colorectal cancer. Getting regular exercise, staying at a healthy weight, and avoiding smoking and heavy alcohol use also help reduce risk.
Even losing a small amount of weight can lower inflammation and improve how the body handles blood sugar, which in turn helps lower cancer risk.
Catching colorectal cancer early is also extremely important. The earlier it’s found, the easier it is to treat. Traditional screening methods like colonoscopy are highly effective, but many people avoid them because they’re uncomfortable or invasive.
This is where a new, non-invasive stool test called COLOTECT may offer a big breakthrough. COLOTECT looks for genetic and other markers in stool that are linked to colorectal cancer. It’s more sensitive than the widely used fecal immunochemical test (FIT), which means it can find cancer at an earlier stage.
Because it’s easier to use and doesn’t require a trip to a hospital, COLOTECT could encourage more people—especially those hesitant to get a colonoscopy—to get screened.
With cancer rates expected to rise by 77% globally by 2050, we need a mix of strategies to fight colorectal cancer. This includes educating people about the link between obesity and cancer, making it easier for people to live healthier lives, and using new technologies like COLOTECT for early diagnosis.
In the end, preventing colorectal cancer isn’t just about one solution. It’s about a combination of healthy living, better screening, and understanding the hidden risks—especially belly fat. By taking action now, we can reduce the number of people affected by this deadly but preventable disease.
If you care about cancer, please read studies about vitamin D and bowel cancer, and a cautionary note about peanuts and cancer.
For more health information, please see recent studies about the link between ultra-processed foods and cancer, and everyday foods to ward off pancreatic cancer.
The research findings can be found in JAMA Network Open.
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