Why being overweight years ago might mean higher cancer risk
Association of Overweight, Obesity, and Recent Weight Loss With Colorectal Cancer Risk
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
People who are overweight often lose weight just before they find out they have colon cancer — so if doctors only check their weight right before diagnosis, they might think weight doesn’t matter. But if you look at weight from years earlier, the link becomes clear.
Surprising Findings
Weight loss of 2+ kg in the last 2 years was linked to a 7.5x higher cancer risk, while weight gain of 2+ kg showed no increased risk.
People assume any weight change might signal cancer—but this study shows only loss, not gain, is a red flag. It’s not about weight fluctuation—it’s about direction and timing.
Practical Takeaways
If you’re over 50 and lose 2 kg or more without trying in the last 2 years, talk to your doctor about colorectal cancer screening—even if you feel fine.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
People who are overweight often lose weight just before they find out they have colon cancer — so if doctors only check their weight right before diagnosis, they might think weight doesn’t matter. But if you look at weight from years earlier, the link becomes clear.
Surprising Findings
Weight loss of 2+ kg in the last 2 years was linked to a 7.5x higher cancer risk, while weight gain of 2+ kg showed no increased risk.
People assume any weight change might signal cancer—but this study shows only loss, not gain, is a red flag. It’s not about weight fluctuation—it’s about direction and timing.
Practical Takeaways
If you’re over 50 and lose 2 kg or more without trying in the last 2 years, talk to your doctor about colorectal cancer screening—even if you feel fine.
Publication
Journal
JAMA Network Open
Year
2023
Authors
Marko Mandic, F. Safizadeh, Tobias Niedermaier, M. Hoffmeister, Hermann Brenner
Related Content
Claims (6)
People with obesity have a higher chance of developing colorectal cancer compared to those without obesity, with men showing a greater increase in risk than women.
People who lose 2 kg or more unintentionally within two years before being diagnosed with colorectal cancer are 7.5 times more likely to have the disease, suggesting this weight loss may signal the presence of early-stage cancer.
Measuring obesity using body mass index (BMI) may not accurately reflect the link between obesity and colorectal cancer because people who later develop colorectal cancer often lose weight before diagnosis, making their BMI appear normal and weakening the observed association.
People who gain 2 kg or more in the two years before being diagnosed with colorectal cancer do not show a statistically significant increase in cancer risk, meaning this level of weight gain is not reliably linked to the presence of early-stage colorectal cancer.
People who had a high body mass index (BMI) 8 to 12 years before being diagnosed with colorectal cancer were more than twice as likely to develop the disease compared to those with a normal BMI, suggesting that carrying excess weight over a long period increases risk, even if weight drops shortly before diagnosis.