WASHINGTON, July 8 (Xinhua) -- Adults who are extremely obese may cut their lives short by up to 14 years because they have increased risk of cancer, heart disease, stroke, diabetes, and kidney and liver diseases, according to a U.S. study out Tuesday.
The findings, published in the U.S. journal PLOS Medicine, were based on an analysis of data pooled from 20 large studies of people from the United States, Sweden and Australia.
"While once a relatively uncommon condition, the prevalence of class III, or extreme, obesity is on the rise. In the United States, for example, 6 percent of adults are now classified as extremely obese," lead author Cari Kitahara of the U.S. National Cancer Institute said in a statement. "Prior to our study, little had been known about the risk of premature death associated with extreme obesity."
After excluding individuals who had ever 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 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 a BMI of 40 to 44.9 to 13.7 years for a BMI of 55 to 59.9, they said. The loss of life by the extremely obese was equal or higher than that of current cigarette smokers among normal-weight participants in the same study.
The BMI is a measure of total body fat and is calculated by dividing a person's weight in kilograms by their height in meters squared. A BMI between 18.5 and 24.9 is considered normal. A BMI between 25 and 29.9 is overweight, a BMI between 30 and 39.9 is considered obese while 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," senior author Patricia Hartge of the U.S. National Cancer Institute said.