Weight, smoking, and mortality.

A controversy has existed concerning the relationship between body habitus and mortality. Original studies found that overweight persons were at risk for increased mortality, but later studies suggested that the very lean were also at high risk. The existence of a U-shaped relationship between mortality and body mass index was confirmed in a reanalysis of a 25-year follow-up of 1,503 men and 1,464 women, initially aged 40 to 65 years. Cigarette smoking did not explain the higher mortality among persons in the lowest body mass index category.