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Trends in Obesity-Related Death and Cardiovascular Risk

Fewer U.S. deaths are attributable to obesity than previously thought, but obesity clearly remains an important risk factor for death and diabetes.

CDC researchers reported in 2004 that poor diet and physical inactivity accounted for more than 400,000 U.S. deaths in 2000 (Journal Watch Cardiology Apr 23 2004). They have since corrected that figure to 365,000 (JAMA 2005; 293:298). Two new CDC studies examine obesity-related trends in the U.S.

In one study, researchers used follow-up data from three National Health and Nutrition Examination Survey (NHANES) cohorts (1971–1975, 1976–1980, and 1988–1994) and the body-mass index distribution in the NHANES 1999–2002 cohort to estimate the number of deaths in 2000 associated with being underweight (BMI, <18.5), overweight (BMI, 25–29.9), or obese (BMI, 30). Compared with normal weight (BMI, 18.5–24.9), obesity accounted for an estimated 112,000 excess deaths (most among people younger than 70), being underweight accounted for 34,000 excess deaths, and (curiously) being overweight accounted for 86,000 fewer deaths.

In the other study, researchers used NHANES data to analyze trends in cardiovascular risk factors. From 1960 to 2000, the prevalence of hyperlipidemia dropped from 34% to 17% overall and from 39% to 18% among obese people; hypertension prevalence declined from 31% to 15% and from 42% to 24%, respectively. Smoking was tracked from 1971 to 2000; prevalence dropped from 39% to 26% overall and from 33% to 20% among obese people. However, the prevalence of diagnosed diabetes increased dramatically from 1960 to 2000: from 2% to 5% overall and from 3% to 10% among obese people.

Comment: These data suggest that fewer deaths are attributable to obesity than previously thought, but obesity clearly remains an important risk factor for death and diabetes. Also, a substantial number of deaths apparently are attributable to being underweight. Some media coverage characterized the smaller number of deaths in the overweight category as a survival advantage in this subgroup, but the finding contradicts much previous evidence in overweight individuals and could reflect a lack of accounting for chronic illnesses in the normal-weight participants. The prevalence of several cardiovascular risk factors has improved considerably in recent decades, but the tripling of diabetes prevalence in the obese population emphasizes the importance of continued aggressive risk-factor modification in this group.

— JoAnne M. Foody, MD

Published in Journal Watch Cardiology May 20, 2005

Citation(s):

Flegal KM et al. Excess deaths associated with underweight, overweight, and obesity. JAMA 2005 Apr 20; 293:1861-7.

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• Medline abstract (Free)

Gregg EW et al. Secular trends in cardiovascular disease risk factors according to body mass index in US adults. JAMA 2005 Apr 20; 293:1868-74.

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• Medline abstract (Free)

Mark DH. Deaths attributable to obesity. JAMA 2005 Apr 20; 293:1918-9.

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• Medline abstract (Free)