We all know by now that being overweight carries all kinds of health risks, from diabetes to heart disease. But did you know that obesity can also increase your cancer risk?
Several recent studies have established a link between being overweight and developing cancer. In fact, a review of more than 1,000 studies shows a significant weight gain, or being overweight or obese, can increase your chances of developing more than a dozen kinds of cancers. 13, in fact, including colorectal, post-menopausal breast, uterine, esophageal, kidney, and pancreatic cancers. These cancers make up 40% of all cancers diagnosed in the United States each year. It’s especially risky for ladies. About 55% of all cancers diagnosed in women are associated with being overweight or obese. Among men, it’s 24%. And it is increasingly diagnosed in young people aged 20 to 49. Breaking it down even more, about 630,000 people in the U.S. are diagnosed with cancer associated with obesity each year. About two out of three of those diagnosed are adults 50 to 74 years old.
The Numbers are Rising
It’s even more telling to compare the rates of obesity-related cancers to those not connected to obesity. Between 2005 and 2014, obesity-related cancers increased by seven percent. In comparison, non-obesity-related cancers declined during that time by 13 percent.
It’s a mistake for people to believe that cancer is predominantly an inherited condition. It is true everyone has an innate or acquired susceptibility to specific types of cancer. Still, in most cases, it only leads to the actual development of cancer after being driven by one or more external risk factors. One of those risk factors is obesity.
Another factor is tobacco use, but obesity has now overtaken that as the number one preventable cause of cancer deaths in the U.S. However, obesity and tobacco use are at least preventable, in contrast to other cancer risk factors like getting older. 
Connection Between Obesity and Cancer Risk
The exact connection between excess body fat and cancer risk is very complex and not completely understood. Experts believe it’s largely due to one thing in particular: inflammation caused by visceral fat, which is the fat that surrounds your vital organs. Excessive visceral fat affects certain processes in your body, including how it manages hormones, like insulin and estrogen. That can lead to increased cancer risk by affecting how and when cells divide and die. Chronic inflammation is typically common in obese people, and research clearly shows it provides a definite increased risk for cancer. To put it simply, cancer occurs when cells reproduce uncontrollably, damaging the cells around them and causing illness. The more cells divide and reproduce, the more risk that a problem will arise and a tumor will form.
People who are obese also often have chronic inflammatory conditions such as gallstones or non-alcoholic fatty liver disease. Both can cause oxidative stress, which leads to DNA damage and increases the risk of biliary tract and other cancers.
Insulin resistance is also linked to being overweight. What exactly is that? Insulin is the hormone that regulates blood sugar, and inflammation can keep the body from properly responding to insulin, causing a resistance, which triggers an increase in insulin. That increase triggers an increase in the number of cells produced, which can lead to cancer.
Obesity can also impact how hormones like estrogen are controlled. More insulin can lead to more available estrogen, which increases cancer risk. That’s because the higher estrogen levels lead to increased cell production, which could lead to tumor growth. Estrogen is important to the body, but too much is common in obese people. For women, that estrogen overload increases the risk for post-menopausal breast, endometrial and ovarian cancers.
Beyond the biological effects, obesity can lead to issues in screening for cancer and management. Screening may be less effective with weight issues. For example, women who are overweight or obese have an increased risk of cervical cancer compared with women of healthy weight. Experts believe ineffective screening contributes to that fact. 
How did we get here?
Obesity is a growing trend in America. A majority of American adults weigh more than recommended. In 2020, almost 32% of adults ages 18 or older were either obese or severely obese. Obesity is becoming normalized to an extent. But that may not be good when it comes to our cancer risk, especially when the risk factors are ignored. Not just because a growing number of people are susceptible to cancer, but because if they are diagnosed, they see worse outcomes after diagnosis and faster metastasis (secondary growths). They’re also likely to see a less effective response to chemotherapy and other treatments, among other things.
Will losing weight help?
Many observational studies show people at the lowest risk of certain cancers are those who gain the fewest pounds during adulthood. Others have found it beneficial to lose weight, though the evidence for that is not as strong yet. 
What will help is to avoid gaining weight by eating a healthy diet and being physically active. Experts say you should aim for 150 minutes of moderate activity each week or 75 minutes of vigorous activity. If you drink alcohol, limit yourself to one drink a day (that’s for women or two for men).
It’s also important to get enough sleep and manage stress. Both of those issues can make you want to eat more and also choose less healthy foods. The great news is all of this not only reduces your chance of cancer but also brings a long list of other health and wellness benefits.
Lower Your Risk
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