Body weight and longevity: insurance experience in Japan.

Adverse effects of obesity on health and longevity are widely known in clinical medicine. The author reports here the result of a study on the relationship of body weight and longevity based on the data obtained by the life insurance cohort study in which he participated. The result is summarized below: 1. Mortality by body weight assumed a U-shaped curve with the nadir near the average weight for both men and women. 2. Because the mortality for some causes went upward toward right or reverse with the shift from underweight to overweight, the curve for all-cause mortality became U-shaped. 3. The relationship between hospitalization ratio and body weight showed substantially the same trend although the cause for hospitalization varied. 4. The body weight showing the lowest mortality was slightly heavier than the average body weight in Japan, which was different from North America. 5. Based on Metropolitan Life's principle of lowest mortality, we published Meiji Life's height and weight tables in order to set the standard body weight for the Japanese today.