Adults with extreme obesity have increased risks of dying at a young age from cancer and many other causes including heart disease, stroke, diabetes, and kidney and liver diseases, according to results of an analysis of data pooled from 20 large studies of people from three countries.
The study, led by researchers from the National Cancer Institute (NCI), part of the National Institutes of Health, found that people with class III (or extreme) obesity had a dramatic reduction in life expectancy compared with people of normal weight. The findings appeared July 8, 2014, in PLOS Medicine.
"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," said Cari Kitahara, Ph.D., Division of Cancer Epidemiology and Genetics, NCI, and lead author of the study. "Prior to our study, little had been known about the risk of premature death associated with extreme obesity."
In the study, researchers classified participants according to their body mass index (BMI), which is a measure of total body fat and is calculated by dividing a person's weight in kilograms by their height in meters squared. BMI classifications (kilogram/meter-squared) are:
The 20 studies that were analyzed included adults from the United States, Sweden and Australia. These groups form a major part of the NCI Cohort Consortium, which is a large-scale partnership that identifies risk factors for cancer death. After excluding individuals who had ever smoked or had a history of certain diseases, the researchers evaluated the risk of premature death overall and the risk of premature death from specific causes in more than 9,500 individuals who were class III 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 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 accuracy of the study findings is limited by the use of mostly self-reported height and weight measurements and by the use of BMI as the sole measure of obesity. Nevertheless, 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 Patricia Hartge, Sc.D., Division of Cancer Epidemiology and Genetics, and senior author of the study.
Reference: Kitahara CM, et al. Association between Class III Obesity (BMI of 40-59 kg/m) and Mortality: A Pooled Analysis of 20 Prospective Studies. PLOS Medicine. July 8, 2014. DOI: 10.1371/journal.pmed.1001673.
NCI Press Officers | Eurek Alert!
Study calculates the speed of ice formation
04.08.2015 | Princeton University
Research investigates whether solar events could trigger birth defects on Earth
21.07.2015 | University of Kansas
Continuing current carbon dioxide (CO2) emission trends throughout this century and beyond would leave a legacy of heat and acidity in the deep ocean. These...
Glacier decline in the first decade of the 21st century has reached a historical record, since the onset of direct observations. Glacier melt is a global phenomenon and will continue even without further climate change. This is shown in the latest study by the World Glacier Monitoring Service under the lead of the University of Zurich, Switzerland.
The World Glacier Monitoring Service, domiciled at the University of Zurich, has compiled worldwide data on glacier changes for more than 120 years. Together...
Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.
What happens if one mixes cold and hot water? After some initial dynamics, one is left with lukewarm water—the system has thermalized to a new thermal...
Physicists from Regensburg and Marburg, Germany have succeeded in taking a slow-motion movie of speeding electrons in a solid driven by a strong light wave. In the process, they have unraveled a novel quantum phenomenon, which will be reported in the forthcoming edition of Nature.
The advent of ever faster electronics featuring clock rates up to the multiple-gigahertz range has revolutionized our day-to-day life. Researchers and...
Researchers have developed an ultrafast light-emitting device that can flip on and off 90 billion times a second and could form the basis of optical computing.
04.08.2015 | Event News
23.07.2015 | Event News
10.07.2015 | Event News
04.08.2015 | Information Technology
04.08.2015 | Power and Electrical Engineering
04.08.2015 | Materials Sciences