Obesity and Mortality

Heart disease is not the only cause of mortality that leads to an increased mortality risk. A major study (reference 5) involving 900,000 U.S. adults, free of cancer at enrollment, were tracked for 16 years. They found that for men with a BMI of 40 and above, the relative risk of death from cancer was 1.5 (margin of error 1.1 to 2.1), and for women - 1.6 (margin of error of 1.4 to 1.8). For BMI values starting at 30 and above, there is a statistically significant risk increase in cancer mortality both for men and for women.

The study finds that in men, kidney cancer, colon and rectal cancer, stomach cancer, liver cancer and pancreas cancer, all show statistically significant risk increases for the most obese. This does not mean that other types of cancer (e.g., prostate cancer) are not impacted by obesity - just that it was not confirmed in this study.

In women, increases in ovarian cancer, non-Hodgkin's lymphoma, breast cancer, gallbladder cancer, cervical cancer, and several other types of cancer, are all statistically significant. Other types of cancer could likewise be impacted, although the data were insufficient to conclusively determine a dependence in this study.

What about other causes of death? Are they impacted by obesity? Since the studies we have referenced involve about one million participants, determination of the impact of obesity on less-prevalent diseases would require even larger studies, requiring a large financial investment to support the effort. There is no definitive answer at this time.

What is the impact of mortality on overweight people (BMI between 25 and 30, lower BMI than obese)? While the results indicate a rise in risk above a BMI of 25, they are not statistically conclusive. However it is reasonable to assume that the risk rises gradually as the BMI increases above 25, becoming large at BMI=30 and above.

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Last Modification - November 22, 2004