Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies
http://www.ncbi.nlm....les/PMC2662372/
"In both sexes, mortality was lowest at about 22·5–25 kg/m2. Above this range, positive associations were recorded for several specific causes and inverse associations for none, the absolute excess risks for higher BMI and smoking were roughly additive, and each 5 kg/m2 higher BMI was on average associated with about 30% higher overall mortality"
"Below the range 22·5–25 kg/m2, BMI was associated inversely with overall mortality, mainly because of strong inverse associations with respiratory disease and lung cancer. These inverse associations were much stronger for smokers than for non-smokers, despite cigarette consumption per smoker varying little with BMI."
"If the overall inverse association at low BMI is partly non-causal, then the real optimum BMI might be somewhat lower than the apparent optimum of about 23 kg/m2 or 24 kg/m2."
"The definite excess mortality below 22·5 kg/m2 is due mainly to smoking-related diseases, and is not fully explained."
(note: figure 6 shows increased mortality below a BMI of 22.5 even amongst those who have never smoked regularly)
Edited by Brett Black, 22 July 2010 - 04:15 AM.