Oxford researchers carried out a meta-analysis 0f 57 cohort studies with a total of 894,576 people to examine the relationship between MBI and mortality. Most of the participants were recruited during 1970s and 80s with an average of 8 years further follow up. They were aged 46 in average at enrollment with BMI 24.8kg/sq m ( BMI>30kg/sq m were considered obese).
Researchers found that people with a normal BMI (22.5 - 25kg/sq m) had the lowest overall mortality. Every 5kg/sq m rise in BMI above 25 increased the risk of death by 30% compared with people having normal BMI. They estimated that average lifespan is reduced by 8 - 10 year for people with BMI above 35kg/sq m. The greatest increase in death risk was associated with diabetes, kidney or liver disease, followed by vascular mortality. They concluded that BMI itself is a strong predictor of overall mortality.
Critics say that this research gives actual figures on mortality risk associated with obesity but they argue that the increased death rate cannot be attributed to obesity alone, diabetes, high blood pressure and bad cholesterol are associated particularly with increased risk of cardiovascular mortality with high BMI, also the effects of diet, exercise and socioeconomic status were not taken into acount.
Source: "Body-mass index and cause-specific mortality in 900,000 adults: collaborative analyses of 57 prospective studies". The Lancet 2009; early online publication, March 18
No comments:
Post a Comment