Thinness and mortality.

The relationship of thinness to mortality was examined in White adult members of the Kaiser Permanente Medical Care Program who had at least three multiphasic health checkups between 1964 and 1972, with mortality follow-up through 1980. A detailed comparison was performed of the mortality patterns of "thin" (decile 1 of Quetelet's index) and "average" weight (deciles 4 and 5) cohort members who were age 40-79 years and free of illness at the beginning of follow-up. Thin male (relative risk 1.6, 95 per cent confidence limits 1.0, 2.6) and female (R.R. 2.1, 95 per cent C.L. 1.1, 3.9) current cigarette smokers were at increased risk of mortality compared with average weight smokers. Unmeasured differences between thin and average weight smokers with respect to quantity of cigarettes smoked may have contributed to the apparent association of thinness with mortality in smokers. Thinness was not associated with increased mortality in never smokers and ex-smokers (R.R. 1.0 in men and women). As association of long-term weight loss with mortality was present in thin and average weight men and in thin women.