People who have been overweight or obese for many years have a higher risk of developing colorectal cancer than those whose weight changed recently, with the highest risk linked to weight measured 8 to 12 years before diagnosis.

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.

People who consistently have excess body weight and excess fat around the abdomen have a 19% higher chance of developing colorectal cancer before age 50 compared to people who maintain a normal weight and no abdominal fat accumulation.

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 fat specifically around the abdomen after being previously lean have a slightly higher chance of developing colorectal cancer at a younger age than those who never gained excess weight.

People with obesity have a higher risk of developing colorectal cancer, based on findings from many large studies, but the size of this risk varies across groups due to differences in how obesity is measured, who is studied, or other unaccounted factors.