The Lancet predicts the United States wants linger far behind other high-income 87.8 years by 2040-comparatively, frontrunner Spain is forecast to boast an average lifespan of 85.8 years while Japan sits at a close second with an expected lifespan of 85.7 years.
Newsweek Daniel Moritz-Rabson reports that the new rankings are the US dropping from 43rd to 64th place. This staggering-21 spot plunge represents the largest decline for a high-income nation and suggests that Americans born in 2040 will not live much longer than those born in 201
The study, which was published by researchers at the University of Washington's Institute for Health Metrics and Evaluation (IHME), Drew on data from the 2016 Global Burden of Disease study to predict life expectancy in 195 countries and territories. Spain, formerly in fourth place, edged out Japan to first, while Singapore (85.4), Switzerland (85.2) and Portugal (84.5) rounded out the remaining five spots.
According to Agence France Presse , the United States' decline since it effectively switches places with China. Now in 39th place thanks to an average lifespan of 81.9 years, the Asian powerhouse was formerly stood out at a lowly 68th.
Other nations projected to enjoy rising expectations, Portugal, which jumped from 23rd to fifth after adding 3.6 years to its average lifespan, and Syria, which is moving from 137th to 80th from 68.2 years to 78.6 years-assuming, of course, that the country's devastating civil war drew to a close.
At the opposite end of the spectrum, CNN's Rob Picheta writes that the landlocked African country of Lesotho stands in a place with a predicted life expectancy of 57.3 years. In total, HIM states in a statement. "Inequalities will continue to be large," IHM Director Christopher Murray said in a statement. "In a substantial number of countries, too many people will continue to learn relatively low incomes, remain poorly educated, and the prematurely." But nations could make faster progress by helping people tackle the major risks, especially smoking and poor diet. "
The top determinants of average lifespan are so-called "lifestyle" diseases, according to AFP. These include high blood pressure, obesity, high blood sugar and alcohol and tobacco use. Air pollution, which is responsible for the loss of one million lives in China every year.
In general, scientists expect mortality to shift from infectious diseases like malaria to chronic and non-communicable disorders such as diabetes, lung cancer and kidney disease.
CNN 's Picheta points out that US life expectancy has actually declined over the past two years, in part because of the country's ongoing opioid crisis, which claimed 63,600 lives in 2016. Obesity thus poses a threat to residents, affecting four in every 10 adults and 18.5 percent of children.  Lifestyle changes could help offset these issues, Brett Molina writes for USA Today . A June report by the Centers for Disease Control and Prevention found that only 23 percent of U.S. adults get enough exercise, while a young man is reading a book on a diet.
The team's findings are not set in stone. In fact, the researchers mapped both best and worst case scenarios. In the former, 158 countries experienced life expectancy gains at least five years, while 46 saw gains of 10 years or more. Lesotho standing at just 45.3 years.
"The future of the world's health is not pre-ordained, and there is a wide range of plausible trajectories, "lead author Kyle Foreman, director of data science at IHME, said in a statement.
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