Life expectancy in the U.S. has grown more slowly over the last two decades than in other high-income countries such as Japan and France, and this can largely be attributed to obesity and the lasting effects of smoking, according to a new report.

For U.S. men, life expectancy increased by 5.5 years from 1980 to 2006, less than the average increase of 21 other countries in the report.

For U.S. women, life expectancy increased by about 3 years from 1980 to 2006, but the average increase achieved by 21 other countries was about 5 years, the report said.

Smoking's "lag effect" the decades between the start of smoking and the time of death and growing obesity rates in the U.S. account for much of our lower-than-average life expectancy increases, said Eileen Crimmins, co-chairwoman of the National Research Council committee that wrote the report.

"We knew the U.S. was lagging behind, but the extent of the lag, and its impact on women, was not expected," Crimmins, chairwoman of gerontology at the University of Southern California, told MyHealthNewsDaily.

Life expectancy for U.S. men is 75.3 years, and for women it's 80.3 years, according to a 2010 National Vital Statistics Report.

Life expectancy is higher in other countries, according to the new report. In Japan, men live to be 79.2 years old on average, and women live to be 86. In France, men live to be 77.4 and women, 84.4, on average.

The report was released today (Jan. 25) by the National Research Council.

The "lag effect"

Because smoking rates have dropped over the last 25 years, life expectancy for U.S. men is expected to rise quickly in the near future, according to the report. For women, who historically started smoking later than men, a surge in life expectancy might come later.

The lag between the drop in smoking rates and the increase in life expectancy exists because toxins from smoking take time to accumulate to such a level that causes death, said S. Jay Olshansky, an epidemiology professor at the University of Illinois, Chicago, who was not involved with the new study.

"It takes decades for the detrimental effects of smoking to be realized," Olshansky told MyHealthNewsDaily.

A similar lag time comes into play with obesity, he said. It can also take decades before serious health effects are made apparent, he said.

We should expect obesity-related deaths to increase in the future, for the same reason deaths from smoking are occurring now, despite the drop in smoking rates, Olshansky said.

The Netherlands and Denmark also have life expectancies that were negatively affected by smoking, the report said.

The influence of U.S. culture

Although smoking and obesity are the two major and obvious factors affecting life expectancy, our society and infrastructure are the ultimate influencers , said Arline T. Geronimus, a professor in the School of Public Health at the University of Michigan, who was not involved with the study.

"There are other kinds of more general cultural factors that would also predispose Americans to more obesity than other countries, like our fast food culture and our transportation culture," Geronimus told MyHealthNewsDaily.

Americans live in a car-friendly society, with lots of urban sprawl that makes cars a necessity to get to school and work, she said. Other countries have big and widely used public transportation systems, so walking is a more necessary part of people's daily lives.

Modern amenities such as phones, TVs and computers make it easy to lead sedentary lifestyles, as do office jobs where people sit for eight hours a day, Geronimus said. And healthy foods are not built into our common food culture as they are in other countries, she said.

"We should both diet and stop smoking, but there are all these other more fundamental contributors that work against our becoming a less obese nation or reducing smoking rates," Geronimus said.

Pass it on: Obesity and smoking are the two main reasons why the U.S. life expectancy is growing more slowly than other developed nations'.

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