- Posted July 9, 2014 by
Morbid obesity decreases life span by up to 16 years
Obesity (BMI of 30 kg/m or over) increases the risk for numerous adverse health outcomes, including most major chronic diseases including diabetes mellitus, cardiovascular disease, hypertension and stroke. Class III, or extreme, obesity (BMI 40 kg/m and over) is emerging as a major public health problem in several developed countries most notably in the US, where BMI>30, 40, or 50 kg/m among adults has increased more than two fold for BMI 30, four fold BMI 40 and tenfold BMI 50.
In the recent past class III obesity was basically uncommon and few studies had specifically evaluated mortality rates associated with class III obesity and in general had limited sample sizes ( fewer than 400 deaths) or did not separately evaluate risks of death for BMI of 50 kg/m or higher. Therefore, there is little significant information about the burden of disease, including total and cause-specific mortality rates, for individuals with BMI values of 40 kg/m and above.
With this in mind Dr. Cari Kitahara, PhD, MHS, research fellow at the U.S. Department of Health and Human Services, National Institutes of Health (NIH), and lead author of study along with colleagues had combined original data from 20 prospective studies from the United States, Sweden, and Australia to evaluate the excess rates of death overall and due to a wide range of specific causes, as well as the expected number of years of life lost attributable to class III obesity. To the best of the research team’s knowledge this is the largest study on this topic to date.
These groups form a major part of the NCI Cohort Consortium which is a large scale partnership that identifies risk factors for cancer death. Participants reporting ever smoking cigarettes or a history of chronic disease (heart disease, cancer, stroke, or emphysema) on baseline questionnaires were excluded. In total the researchers evaluated 9,564 class III obesity participants, for the risk of premature death overall and the risk of premature death from specific causes.
Among the class iii obesity participant’s mortality rates were 856 for men and 663 for women during the study period (1976–2009). Among the 304,011 normal weight participants the mortality rates were 346 in men and 280 in women.
Deaths from heart disease contributed largely to the excess rates in the class III obesity group 238.9 in men and 132.8 in women followed by deaths from cancer 36.7 in men and 62.3 in women, and diabetes 51.2 in men and 29.2 in women.
Within the class III obesity range, after adjustment for hazard ratios total death s and deaths due to heart disease, cancer, diabetes, nephritis/nephrotic syndrome/nephrosis, chronic lower respiratory disease, and influenza/pneumonia increased with increasing BMI.
In comparison to normal weight BMI years of life lost were 6.5 years for those with a BMI of 40 to 44.9, BMI of 45 to 49.9 was 8.9 years of life lost, BMI of 50 to 54.9 was 9.8 years of life lost and for a BMI of 55 to 59.9 kg/m was associated with an average of 13.9 years of life lost.
According to Dr. Kitahara, "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 researchers write, “The accuracy of these findings is limited by the use of self-reported height and weight measurements to calculate BMI and by the use of BMI as the sole measure of obesity. Moreover, these findings may not be generalizable to all populations. Nevertheless, these findings highlight the need to develop more effective interventions to combat the growing public health problem of class III obesity.”
In closing Patricia Hartge, ScD, Division of Cancer Epidemiology and Genetics, and senior author of the study remarked "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. ‘
This study appears in PLoS Medicine.
Ideal BMI 19-25
Severely Obese >35
Morbidly Obese >40
Super Obese >50