According to the study by researchers from the National Cancer Institute (NCI), people with class III obesity (35.0-39.9 BMI) had a dramatic reduction in life expectancy compared with people of normal weight.
Cari Kitahara, Ph.D., Division of Cancer Epidemiology and Genetics, said that while once a relatively uncommon condition, the prevalence of class III, or extreme, obesity is on the rise. In the United States, for example, six percent of adults are now classified as extremely obese, which, for a person of average height, is more than 100 pounds over the recommended range for normal weight.
The researchers found that the risk of dying overall and from most major health causes rose continuously with increasing BMI within the class III obesity group. Statistical analyses of the pooled data indicated that the excess numbers of deaths in the class III obesity group were mostly due to heart disease, cancer and diabetes. Years of life lost ranged from 6.5 years for participants with a BMI of 40-44.9 to 13.7 years for a BMI of 55-59.9.
To provide context, the researchers found that the number of years of life lost for class III obesity was equal or higher than that of current (versus never) cigarette smokers among normal-weight participants in the same study.
The study was published in PLOS Medicine.