A comprehensive review published
in 2013 in the 'Journal of the American Medical Association'
examined the relationship of BMI (Body Mass Index) to death rates.
The study researchers found that increasing levels of obesity were
associated with progressively higher premature death rates.
Mildly obese people, however, did not have a significantly greater
risk of death compared to those with a normal BMI. In fact, the
finding that people classified as overweight but not obese had a
lower overall death rate compared to those with a normal BMI.
Researchers are exploring possible reasons for this finding.
The 'International Journal of Obesity' published a study in 2012
comparing BMI and waist circumference as predictors of life
expectancy. The authors reported that waist circumference is a
better predictor of death from any cause than BMI. The researchers
also found that adults with a high waist circumference had an
increased risk of death regardless of BMI. Although neither BMI nor
waist size can accurately foretell the life expectancy of any
individual, waist circumference may be a better tool for estimating
longevity. In other words, they are saying 'we cannot accurately
tell life expectancy with either of these measurements, but it
does help get us grants and headlines'.