31. Lesotho

Average lifespan: 52.9 years

Lesotho has the lowest life expectancy in the world, despite having a low alcohol prevalence at 30 percent and lower annual alcohol consumption than many countries with a high life expectancy.

The country consumes an average of five liters of pure alcohol per person per year -- half the amount that Australians, Spaniards and South Koreans drink.

Lesotho also has a low prevalence of drug use disorders at 0.8 percent, an obesity prevalence of 16.6 percent and a smoking prevalence of 54.3 percent.

Researchers ranked 30 countries based on life expectancy. We took a look at the top 5 -- and the bottom 5.

The article below details some surprising factors that can affect life expectancy.

Where does the U.S. fit in? Take a look at the slideshow. (Photos: Shutterstock)

TOP 5 COUNTRIES FOR LIFE EXPECTANCY

5. France

Average lifespan: 82.9 years

France has the highest prevalence of alcohol use, the largest annual alcohol consumption and the greatest smoking prevalence out of the countries with a high lifespan, with smokers burning through an average of 14.4 cigarettes per day.

France’s high life expectancy may in part be due to the low working hours, with the French spending 35 hours at work per week - 13 hours less than the highest permitted amount.

The country also has a high vaccination rate at 98 percent.

4. Singapore

Average lifespan: 82.9 years

Singapore has a low prevalence of alcohol usage when compared to the other locations with a high life expectancy, with Singaporeans consuming an average of just two liters of pure alcohol each year -- five times less than Spain and Australia’s consumption.

The country also claims a low prevalence of drug disorders and a low prevalence of obesity at 6.1 percent.

Singapore also has a high number of working hours, with workers expected to put in 44 hours per week.

3. Spain

Average lifespan: 83.1 years

Spain has the second highest smoking prevalence when compared to other locations with a high life expectancy, sitting at 46.2 percent, with smokers consuming an average of 20 cigarettes per day.

The country also has a high prevalence of drug use disorders and a mean BMI that sits 4.6 points above health guidelines.

Spain also claims one of the highest levels of meat consumption, with each person consuming an average of 97 kilograms each year - more than double the global average.

2. Switzerland

Average lifespan: 83.3 years

Switzerland has the second highest life expectancy in the world, despite having a higher prevalence of alcohol use and a high level of alcohol consumption per year.

The country also has the highest working hours, with the Swiss spending 15 hours more at work per week than the French. The country also has one of the lowest levels of air pollution, sitting just 2ug/m3 above the recommended annual mean.

1. Japan

Average lifespan: 84.2 years

Japan has the highest life expectancy in the world, which in part may be due to its healthy diet.

The country has the lowest mean BMI and the lowest prevalence of obesity when compared to the other locations with a high life expectancy, while each person in Japan consumes 45.9 kilograms of meat annually - slightly higher than the global average.

Japan also has one of the highest levels of daily cigarette consumption, with smokers burning through an average of 23.8 cigarettes per day.

16. United States

The U.S. is not on either list -- neither top 5, nor bottom 5 for life expectancy -- but right in between -- at No. 16 -- with an average life expectancy of 78.7 years.

While the average U.S. workweek is 33 hours, the U.S. has the highest meat consumption of the 31 countries studied, at 115.13 kilograms per person; highest prevalence of obesity, at 36.2 percent; and highest mean BMI, at 29.1.

BOTTOM 5 COUNTRIES FOR LIFE EXPECTANCY

27. Chad

Average lifespan: 54.3 years

Chad has the lowest level of cigarette consumption of any country featured, with smokers burning through an average of just one cigarette per day.

The country also has a low mean BMI at 21.5, sitting 0.5 points below the recommended guideline and almost 7 points below New Zealand.

Just 55 percent of the population is vaccinated and only 10 percent of the population has access to basic sanitation -- the same level as South Sudan.

28. The Ivory Coast

Average lifespan: 54.6 years

The Ivory Coast has one of the highest levels of annual alcohol consumption compared to other countries with a low life expectancy, at 8.4 liters -- more than double the amount consumed in Israel and four times that in Singapore.

The country also has one of the highest vaccination rates in comparison to other low lifespan locations, with 83 percent of children under one being inoculated, although just 30 percent of the population has access to basic sanitation.

29. Sierra Leone

Average lifespan: 53.1 years

Sierra Leone has the highest prevalence of alcohol usage when compared to other countries with a low life expectancy, sitting at 44.7 percent, with drinkers consuming an average of 5.7 liters of pure alcohol per year.

The country also claims the second highest smoking prevalence at 50.1 percent, with more than half of the population consuming an average of 4.5 cigarettes per day.

The country has the lowest level of meat consumption per year at 7.3 kilograms -- 35.7 kilograms below the global average.

30. Central African Republic

Average lifespan: 53 years

The Central African Republic consumes just 33.5 kilograms of meat per person per year -- 7.5 kilograms below the global average.

As one of the poorest countries in Africa, the low lifespan may be attributed to malnourishment and lack of health care, with the country reporting an obesity prevalence of 7.5 percent and the rate of vaccination sitting at 47 percent.

The country also has a high level of air pollution with 46.5ug/m3 -- almost ten times the pollution recorded in Sweden and 36.5ug/m3 above the recommended level.

31. Lesotho

Average lifespan: 52.9 years

Lesotho has the lowest life expectancy in the world, despite having a low alcohol prevalence at 30 percent and lower annual alcohol consumption than many countries with a high life expectancy.

The country consumes an average of five liters of pure alcohol per person per year -- half the amount that Australians, Spaniards and South Koreans drink.

Lesotho also has a low prevalence of drug use disorders at 0.8 percent, an obesity prevalence of 16.6 percent and a smoking prevalence of 54.3 percent.