BMI and mortality

The Body Mass Index (BMI) is one way of assessing weight categories. According to a study published online by the medical journal Lancet, high and Low BMIs were associated with increased mortality risk.

This large research examined data from 57 prospective studies with 894,576 participants, mostly in western Europe and North America. Mortality was lowest among those associated with BMIs in the range of 22.5 to 25 kg/m2. Above 25, every 5-unit increase in BMI translated to a serious 40% higher risk for death from ischemic heart disease or stroke and 10% increased risk for cancer-related deaths.

The authors commented "Although other anthropometric measures (eg, waist circumference, waist-to-hip ratio) could well add extra information to BMI, and BMI to them, BMI is in itself a strong predictor of overall mortality both above and below the apparent optimum of about 22.5—25 kg/m2."

Even though the "normal" BMI range is usually quoted to start from BMI of 18.5, the study showed that adults whose BMI was below 22.5 were also at higher risk for death. However, such a higher mortality was mainly, but not entirely, due to smoking-related lung diseases and cancer.

This important study was funded by UK Medical Research Council, British Heart Foundation, Cancer Research UK, EU BIOMED programme, US National Institute on Aging, and Clinical Trial Service Unit (Oxford, UK).

Reference article:
Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies. Prospective Studies Collaboration. Lancet. 2009 Mar 28;373:1083-1096.
(Abstract)
doi:10.1016/S0140-6736(09)60318-4
(How to use the doi system?)