01.Life expectancy fears for the extremely obese
People with extreme obesity die up to 14 years earlier than people of normal weight and have a life expectancy on par with, or below, that of smokers, a study by the US-based National Institutes of Health (NIH) has found.
Extreme obesity, or class III obesity, is defined as having a body mass index (BMI) of 40 or higher.
"While once a relatively uncommon condition, the prevalence of class III, or extreme, obesity is on the rise," says Dr Cari Kitahara, lead author of the study. In the United States, six per cent of adults are now classified as extremely obese, and Australia isn't far behind at 4.2%.
"Prior to our study, little had been known about the risk of premature death associated with extreme obesity," says Kitahara.
The research, led by the National Cancer Institute in the United States, assessed the risk of premature death for more than 9500 people who were class III obese and 304,000 people of normal weight in the US, Australia and Sweden. The data excluded participants who had ever smoked or who had a history of disease.
Within the class III obesity group, the overall risk of death increased in relation to BMI, with years of life lost ranging from six and a half years for participants with a BMI of 40-44.9, to about 14 years for a BMI of 55-59.9. The most common causes of death were heart disease, cancer and diabetes. Other causes included stroke, and kidney and liver diseases.
"Given our findings, it appears that class III obesity is increasing and may soon emerge as a major cause of early death in this [the US] and other countries worldwide," says Patricia Hartge, senior author of the study.
To calculate your BMI, and to find out about other important health measurements such waist circumference, body fat and cholesterol levels, see our article on body numbers.
- Normal weight: 18.5-24.9
- Overweight: 25.0- 29.9
- Class I obesity: 30.0-34.9
- Class II obesity: 35.0-39.9
- Class III obesity: 40.0 or higher