That prediction, which is based on the dramatic rise in obesity, especially among young people and minorities, is from a special report appearing in the March 17 issue in the New England Journal of Medicine.
The study determines that obesity currently reduces life expectancy by approximately four to nine months.
"The magnitude of that effect may sound trivial to some, but in fact it's greater than the negative effect of all accidental mortality, such as car accidents, suicides and homicides combined," said Olshansky, who is professor of epidemiology in the UIC School of Public Health.
The researchers also predict that the rapid rise in obesity among children and teenagers in the past 30 years will have life-shortening effects in the future -- perhaps enough to offset any improvements in longevity from anticipated advances in biomedical technology.
Researchers also believe the life-shortening effect of obesity could rise so rapidly in the United States -- from two to five years in the next 50 years -- that it may eventually exceed the current life-shortening effects of cancer or ischemic heart disease.
The findings are contrary to what some scientists predict about human life expectancy, which assumes that past increases will continue indefinitely. Most forecasts of life expectancy are based on historical trends, but the authors conclude that such estimates fail to consider the obesity epidemic.
Olshansky and colleagues argue that current extrapolation models used to predict life expectancy do not take into consideration the health status of people currently alive.
Longevity predictions are crucial for health policy and for economic policy as well.