Study finds extreme obesity may cut lifespan up to 14 years

The findings were based on an analysis of data pooled from 20 studies of people from the United States, Sweden and Australia, Xinhua news agency reports.

"While once a relatively uncommon condition, the prevalence of class III or extreme obesity is on the rise.

In the United States, six percent of adults are classified as extremely obese," said lead author Cari Kitahara of the U.S. National Cancer Institute in a statement.

"Prior to our study, little had been known about the risk of premature death associated with extreme obesity," Kitahara said.

After excluding individuals who had smoked or had a history of certain diseases, the researchers studied more than 9,500 individuals who were extremely obese and 304,000 others who were classified as having normal weight.

The researchers found that the risk of dying overall and from most major health causes rose continuously with increasing body mass index (BMI) within the class III obesity group.

On average, years of life lost ranged from 6.5 years for participants with BMI of 40 to 44.9 to 13.7 years for BMI of 55 to 59.9. Loss of life among the extremely obese was equal or higher than that of current cigarette smokers among normal-weight participants in the same study.

A BMI between 18.5 and 24.9 is considered normal, between 25 and 29.9 overweight, between 30 and 39.9 obese and a BMI over 40 is considered extremely obese.

The researchers noted the results highlight the need to develop more effective interventions to combat the growing public health problem of extreme obesity.

"Given our findings, it appears that class III obesity is increasing and may soon emerge as a major cause of early death in this and other countries worldwide," said senior author Patricia Hartge of U.S. National Cancer Institute.

The findings were published in the U.S. journal PLOS Medicine.