A pooled analysis of 20 prospective studies from the U.S., Sweden and Australia examined the risk of death and years of life expectancy lost associated with class III obesity, defined as having a body mass index of 40.0 or higher.

Compared with normal-weight BMI, class III obesity was estimated to be associated with up to 14 years of life lost. Statistical analyses indicated that the excess numbers of deaths in the class III obesity group were mostly due to heart disease, cancer and diabetes.

“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, Sc.D., said in a National Institutes of Health news release.

The study, “Association between Class III Obesity (BMI of 40–59 kg/m2) and Mortality: A Pooled Analysis of 20 Prospective Studies,” was published July 8 in PLOS Medicine.