More than one third of the US adult population is obese; the number rises every year. The effects of obesity only begin on the surface--it is a serious condition that leads to heart disease, diabetes and can increase the risk of certain cancers. These people are frequently unaware of the severe consequences of their condition so the National Cancer Institute (NCI) has completed a study to open the eyes of those suffering from obesity.

Led by Cari Kitahara, PhD, the research concluded that class III obesity or a body mass index (BMI) of 40 or higher could shorten life expectancy by 15 years. "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. Prior to our study, little had been known about the risk of premature death associated with extreme obesity."

The research looked at 20 different studies from Sweden, Australia and the United States. With the information of over 9500 participants classified as extremely obese and over 300,000 others who were considered normal weight, the team assessed risks for heart disease, cancer and premature death in both of the groups. The published report concluded that these three afflictions were major causes of death in class III obese people. Even more shocking, the study stated that a BMI of 40-45 would likely mean around a 6 year decrease in lifespan and a BMI of 55-60 could bring death almost 15 years early. The study pointed out the parallel between these numbers and the numbers of the same statistics for smoking, as heavy smokers can also expect a similarly early demise.

"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 Patricia Hartge, ScD, senior author of the study.