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Obesity May Shorten Life by 14 Years

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…. 

In a new study, researchers pooled data from 20 large studies of people from 3 countries and found that people with class 3 obesity had a dramatic reduction in life expectancy compared with people of normal weight.

Lead author Cari Kitahara, PhD, Division of Cancer Epidemiology and Genetics, National Cancer Institute (NCI), part of the National Institutes of Health (NIH), Bethesda, Maryland, said that, "While once a relatively uncommon condition, the prevalence of class 3, or extreme, obesity is on the rise."

"In the United States, for example, 6% 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," she said. "Prior to our study, little had been known about the risk of premature death associated with extreme obesity."

The 20 studies in the analysis included adults from the US, Sweden, and Australia. 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 3 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 body mass index (BMI) within the class 3 obesity group. Statistical analyses of the pooled data indicated that the excess numbers of deaths in the class 3 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 to 59.9. To provide context, the researchers found that the number of years of life lost for class 3 obesity was equal or higher than that of current (versus never) cigarette smokers among normal-weight participants in the same study.

"Given our findings, it appears that class 3 obesity is increasing and may soon emerge as a major cause of early death in this and other countries worldwide," said senior author Patricia Hartge, Division of Cancer Epidemiology and Genetics, NCI.

Practice Pearls:

  • In the U.S., 6% of adults are now classified as extremely obese
  • The risk of dying overall and from most major health causes rose continuously with increasing body mass index (BMI)
  • 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 to 59.9.

National Institutes of Health – published in PLOS Medicine, July 2014