Body Mass Index and Old Age Survival: A Comparative Study between the Union Army Records and the NHANES-I Epidemiological Follow-up Sample

Dejun Su, University of Chicago

In this paper, I made a historical investigation of the BMI-mortality association among white male Americans through a comparative survival analysis between the Union Army Records and the NHANES-I Epidemiological Follow-up sample. The results indicate that the association between BMI and old age survival is historically dynamic, rather than stable. With the whole American population having moved into a higher BMI regime, the optimal BMI has also experienced a substantial upward shift, from (20.4-22.0) in the late 19th century to (24.9-26.9) in early 1970s. In both samples, those who were seriously underweight are associated with a higher risk of mortality. The mortality penalty associated with the highest BMI quintile has declined substantially since the late 19th century. The implications of these findings to the future trend in old age mortality among white male Americans are discussed.