Weight gain & colon cancer risk

Being overweight and obese [body mass index (BMI) > 25] has been shown to be associated with increased risk of colon cancer, especially among men. Even when you are not overweight / obese, will weight change in adulthood have an influence on your subsequent colon cancer risk?

Researchers from the Harvard School of Public Health examined this question by studying 46,349 men, aged 40 – 75, who were participating in the Health Professionals Follow-up Study (Int J Cancer 2008; 123: 1160 – 1165). All men were cancer free at baseline and were followed up for an 18 – year period, from 1986 to 2004. A cumulative mean BMI > 22.5 was found to be associated with an increased risk of colon cancer. A short term weight gain of 10 pounds (4.54 kg) in the prior 2 – 4 years was significantly associated with increased risk of colon cancer. For every 10 pounds gained, the risk is increased by 14%. The risk of colon cancer is increased by 33% for every 10 pounds of weight gained per 10 years since age 21.

The above study involved men only. What happens in women? Will weight loss affect cancer risk in women? A study from the University of Minnesota looked at the influence of voluntary weight loss on the incidence of cancer in post-menopausal women (Int J Obes Relat Metab Disord 2003; 27; 1447 – 1452). The research studied 21,707 women, cancer free at baseline, over the period 1993 to 2000. Compared to women who never had voluntary weight loss of ≥ 20 pounds during adulthood, the incidence rates for all obesity – related cancer was lowered by 14% in those women who had voluntary weight loss. For specific cancers, voluntary weight loss led to a 19%, 9% and 4% reduction in the incidence rate of breast, colon and endometrial cancers respectively.

Putting on weight is associated with increased cancer risk. In addition it is also associated with increased cardiovascular and metabolic health risks. I am sure that the intention of these and other studies on the ill effects of weight gain is certainly not to scare you away from enjoying your food. If you eat healthily, consume moderately, exercise and watch your weight, you can still enjoy your food without exposing yourself to the added risk of developing cancers, ischaemic heart disease and diabetes.