Extreme obesity may shorten life expectancy by up to 14 years



The prevalence of extreme obesity is on the rise, with six percent of U.S. adults now classified as extremely obese (class III obesity, with a body mass index (BMI) of 40 kg/m2 or above). Little information exists on the rates of total or cause-specific deaths associated with extreme obesity.


IRP researcher Cari Kitahara, Ph.D., and colleagues used data from 20 prospective cohort studies to show that risk of dying is substantially higher for individuals with class III obesity, and the risk continues increasing as BMI goes up. A person with BMI between 40 and 59 kg/m2 experienced an estimated 6.5 to 13.7 years of life loss, compared to a normal weight person with similar characteristics. The loss in life expectancy attributable to extreme obesity was similar to the difference in life expectancy between current and never cigarette smokers.


The team’s findings suggest that class III obesity is associated with a substantially increased rate of death and may soon emerge as a major cause of death in this and other countries worldwide.


Kitahara CM, Flint AJ, Berrington de Gonzalez A, Bernstein L, Brotzman M, MacInnis RJ, Moore SC, Robien K, Rosenberg PS, Singh PN, Weiderpass E, Adami HO, Anton-Culver H, Ballard-Barbash R, Buring JE, Freedman DM, Fraser GE, Beane Freeman LE, Gapstur SM, Gaziano JM, Giles GG, Håkansson N, Hoppin JA, Hu FB, Koenig K, Linet MS, Park Y, Patel AV, Purdue MP, Schairer C, Sesso HD, Visvanathan K, White E, Wolk A, Zeleniuch-Jacquotte A, Hartge P. (2014.) Association between Class III Obesity (BMI of 40–59 kg/m) and Mortality: A Pooled Analysis of 20 Prospective Studies. PLOS Medicine. 11(7), e1001673.

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This page was last updated on Thursday, June 15, 2023