Obesity has long been established as a risk factor for cancer, particularly when it’s stored in certain areas of the body.

Now, new research suggests that a larger waist circumference is a bigger risk factor than body mass index (BMI) for obesity-related cancers — but only for men, not for women.

The findings, which were published in the Journal of the National Cancer Institute, will be presented in May at the European Congress on Obesity in Malaga, Spain.

BMI IS WRONG WAY TO MEASURE OBESITY, RESEARCHERS SAY

The study was led by Dr. Ming Sun, Dr. Josef Fritz and Dr. Tanja Stocks from Lund University in Sweden.

The researchers analyzed data from 340,000 Swedish people averaging 51 years of age whose BMI and waist circumference assessments were performed between 1981 and 2019, according to a press release.

They then compared those statistics to cancer diagnoses pulled from the Swedish Cancer Register.

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Over a period of 14 years, there were 18,185 diagnoses of obesity-related cancers among the patients in the study.

For men, an increase in waist circumference of around 11 cm resulted in a 25% higher risk of obesity-related cancer.

This was a bigger risk factor than having an increased BMI, which increased the chances by 19%.

For men, an increase in waist circumference of around 11 cm resulted in a 25% higher risk of obesity-related cancer. (iStock)

For women, an increase of about 12 cm in waist circumference and an increase in BMI were both linked to a 13% greater cancer risk, the study found.

Obesity-related cancers include cancers of the oesophagus (adenocarcinoma), gastric (cardia), colon, rectum, liver/intrahepatic bile ducts, gallbladder, pancreas, breast (postmenopausal), endometrium, ovary, renal cell carcinoma, meningioma, thyroid and multiple myeloma, the release stated.

“BMI is a measure of body size, but does not provide information on fat distribution, whereas waist circumference is a proxy more closely related to abdominal adiposity.”

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Overall, the researchers found waist circumference to be a more accurate cancer predictor than BMI.

“BMI is a measure of body size, but does not provide information on fat distribution, whereas waist circumference is a proxy more closely related to abdominal adiposity,” they wrote. 

“This distinction is crucial because visceral fat, which accumulates around the abdominal organs, is more metabolically active and has been implicated in adverse health outcomes, including insulin resistance, inflammation and abnormal blood fat levels. Consequently, individuals with similar BMIs may have distinct cancer risks due to differences in fat distribution.”

Why the difference between men and women?

One potential reason for the gender discrepancy, according to the researchers, is that men are more likely to store fat viscerally (in the belly), while women generally accumulate more subcutaneous fat (under the skin) and peripheral fat (in the arms and legs). 

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“Consequently, waist circumference is a more accurate measure of visceral fat in men than in women,” the researchers wrote.

“This may make waist circumference a stronger risk factor of cancer in men, and explain why waist circumference adds risk information beyond that conveyed by BMI in men, but not women.”

The researchers suggested that combining hip circumference with waist circumference in women could give a more accurate estimation of visceral fat. (iStock)

Excess body fat is also linked to higher insulin levels in men than in women, the researchers noted, which could be a factor in waist circumference being more strongly linked to men’s cancer risk.

“The divergence in how waist circumference and BMI relate to cancer risk between men and women underscores the complexity of the impact of adiposity (excess body fat) on cancer development,” the researchers wrote. 

“It suggests that considering biological and physiological differences between the sexes might be helpful when assessing cancer risk. Further research is needed to explore these sex differences.”

They also suggested that combining hip circumference with waist circumference in women could give a more accurate estimation of visceral fat.

“Waist circumference is a more accurate measure of visceral fat in men than in women,” the researchers wrote. (iStock)

Dr. Marc Siegel, clinical professor of medicine at NYU Langone Health and Fox News senior medical analyst, was not involved in the study, but reinforced that BMI is a “good indicator of obesity, but is not the only one.”

“Belly fat contains a lot of the inflammatory chemicals that act as carcinogens.”

“Obesity leads to inflammation, and inflammation correlates with many kinds of cancer, including breast and prostate and cancers of the gastrointestinal tract,” he told Fox News Digital.

“It is not surprising that waist circumference in men could be a more precise indicator if measured properly, because belly fat contains a lot of the inflammatory chemicals that act as carcinogens,” the doctor noted.

Obesity-related cancers include cancers of the oesophagus (adenocarcinoma), gastric (cardia), colon, rectum, liver/intrahepatic bile ducts, gallbladder, pancreas, breast (postmenopausal), endometrium, ovary, renal cell carcinoma, meningioma, thyroid and multiple myeloma. (American Cancer Society/Getty Images)

For women, where fat distribution is somewhat different, Siegel agrees that it “makes sense” to consider both waist and hip circumference, as the Swedish study suggests. 

“The study looks at over 300,000 people and is an important new reference, but it is observational, so it shows an association, but not proof,” the doctor added.

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Dr. Brett Osborn, a Florida neurosurgeon and longevity expert, also detailed the different ways in which men and women store fat.

“While women accumulate more subcutaneous fat — on the hips, thighs and buttocks — men pack it around the waist, deep inside the abdomen,” Osborn, who was not involved in the study, told Fox News Digital. 

“This is visceral fat, and it’s metabolically toxic. It’s not just sitting there. It’s active, like a gland, secreting inflammatory chemicals (cytokines), raising insulin levels, disrupting hormones and laying the groundwork for cancer cell growth.”

Strength training three times per week is ideal, one doctor advised, adding, “Resistance training reduces visceral fat and inflammation.” (iStock)

Osborn reiterated that BMI is limited in its ability to accurately measure excess fat.

“First, BMI doesn’t factor in muscle mass, so a short, stocky individual with a low body fat percentage may be categorized as overweight or obese, when in fact quite the opposite is true,” he said.

“Second, BMI doesn’t tell you where the body fat is, and as it turns out, that’s what’s critical — at least in men.”

Minimizing risk

To reduce cancer risk, Osborn recommends that men measure their waistlines to ensure they’re in a healthy range. People can also track their visceral fat score on a medical-grade anthropometry scale, he said. 

“Understand that belly fat isn’t just cosmetic — it’s carcinogenic.”

“Anything above 40 inches (102 cm) is a red flag,” he told Fox News Digital.

Strength training three times per week is ideal, the doctor advised, adding, “Resistance training reduces visceral fat and inflammation.”

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Proper nutrition is also important, he said. “Eat like your life depends on it — because it does. Stop feeding your cancer risk.”

“Understand that belly fat isn’t just cosmetic — it’s carcinogenic,” Osborn added. “You may not feel it now, but the clock is ticking. Visceral fat is silent, aggressive and deadly — and it’s doing damage even if your BMI is ‘normal.’”