Objective: To clarify the influence of overweight and underweight on the total mortality as well as on different causes of death in an unselected population of old people.
Design: The cohort of the aged population was examined in 1971. The survival time of the cohort was followed for ten years.
Settings: Rural commune of Hankasalmi in Central Finland.
Participants: 721 (80% of total aged population) subjects aged 65 years or over (310 men and 411 women).
Outcome measures: 10 years survival rate and causes of death by body mass index quartiles and sex.
Results: The women in the lowest BMI quartile had the highest mortality in ten-year follow-up (a 26% decrease in survival time). The differences between the total mortality of the other quartiles were small. In the lowest BMI quartile there was overmortality from respiratory diseases and tumours, and undermortality from cardiovascular diseases. In the highest BMI quartile the main groups of causes of death did not differ essentially from those in the whole cohort.
Conclusion: Underweight was as strong a predictor of mortality, and even stronger, than overweight.