Forecasts of life expectancy are an important component of public policy that influence age-based entitlement programs such as Social Security and Medicare. Although the Social Security Administration recently raised its estimates of how long Americans are going to live in the 21st century, current trends in obesity in the United States suggest that these estimates may not be accurate. From our analysis of the effect of obesity on longevity, we conclude that the steady rise in life expectancy during the past two centuries may soon come to an end.

Starved to Life?: Caloric restriction—reducing the calories ingested by around 30% of that of a normal, fit individual—leads to substantial increases in life span in experimental animals. In an extensive study of caloric restriction in primates, Colman et al. (p. 201 ) report that rhesus monkeys, which were subjected to caloric restriction as adults and followed for the last 20 years, show decreased mortality and delayed onset of age-related diseases when compared to normally fed control animals. If compliance with such a diet were not so difficult, many humans would be strongly tempted to enjoy the decreased incidence of brain degeneration, cardiovascular disease, diabetes, and cancer apparent in this population of monkeys.

Many public health officials and organizations have tried to warn the public about the dangers of obesity.^1,2 One of the strongest warnings came from the US surgeon General who stated that a failure to address overweight and obesity "could wipe out some of the gains we've made in areas such as heart disease, several forms of cancer, and other chronic health problems."³

Obesity is a serious medical problem, increasing in prevalence, affecting millions,¹ and of great interest to the public. To articulate the burden of obesity, investigators have used indicators such as prevalence,^1,2 economic cost,³ and association with risk factors and diseases.⁴ However, there is little published scientific information on the number of annual obesity-attributable deaths in the United States.