U.S. life expectancy 2040, study finds

When compared with other nations, however, the U.S. is predicted to plunge in life expectancy rankings, from 43rd two years ago to 64th.

It would represent the largest drop in ranking among high-income nations, found the study, published this week in the journal Lancet.

By comparison, the United Kingdom will boast a life expectancy of 83.3 years, ranking 23rd in the world.

Several studies have shown Americans are eating healthy enough to get exercise. A report published in June by the Centers for Disease Control and Prevention, 23 percent of U.S. adults are getting enough exercise.

Meanwhile, a few people are eating enough fruits and vegetables.

Adopting healthier clothes could help more Americans live a lot longer. A study published in April found following such routines as healthy eating, exercising regularly, and maintaining a healthy weight as you get 10 years to your life.

Overall, the IHME study said in a worst-case scenario, half of all nations could watch their average life expectancies drop.

Although the study is also growing in these diseases, the researchers said there is still time to reverse race.

"The future of the world is not pre-ordained, and there is a wide range of plausible trajectories," said lead study author Dr. Kyle Foreman, Director of Data Science at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, in a statement. "But it is a question of significant progress or stagnation.

Spain is forecast to overtake the world with the highest life expectancy in 2040, at 85.8 years, the study found.