Is the High Level of Obesity in the United States Related to Its Low Life Expectancy?

Samuel Preston, Andrew Stokes

NBER Retirement Research Center Paper No. NB 10-01B
Issued in September 2010

This paper investigates the effect of obesity on the life expectancy gap between the United States and other developed countries. We perform primary analyses of survey data to identify the distribution of body mass index (BMI) by age and sex in 16 countries. The United States has the highest proportion obese of any population considered. These BMI distributions are combined with three alternative sets of mortality risks by BMI in order to estimate the proportion of deaths attributable to above‐optimal weight, by age and sex. These estimates are then converted into their implications for longevity. Our baseline analysis uses the largest, longest, and most internationally‐diverse collection of obesity risks, the Prospective Studies Collaboration. Using this set of risks, we estimate that US life expectancy at age 50 in 2006 was reduced by 1.29 years for women and 1.61 years for men as a result of obesity. Using obesity risks that were recorded more recently in the United States, the reduction is in the range of 0.6‐0.9 years. Even using these lower risks, we find that differences in obesity account for a fifth to a third of the shortfall of life expectancy in the US relative to longer‐lived countries.

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