Under- and overweight impact on mortality among middle-aged Japanese men and women: a 10-y follow-up of JPHC study cohort I.
OBJECTIVE
Although obesity is a major health problem in Western countries, its impact may differ in another culture. This paper examines the association between body mass index (BMI; kg/m2) and mortality in Japan, where the mortality profile and BMI distribution differ substantially from Western countries.


METHODS
The JPHC Study cohort I, a population-based prospective study in four public health center areas, started in 1990 and was followed-up to the end of 1999.


METHODS
A total of 19,500 men and 21,315 women aged 40-59 y who submitted their body weight and height and did not report any serious disease at baseline.


METHODS
Risk of death by category of BMI.


RESULTS
During 10 y of follow-up, 943 and 483 deaths were documented in the men and women, respectively. The association between BMI and all-cause mortality was U-shaped: compared with a category of 23.0-24.9, the statistically significant elevations in relative risk were observed in both under- and overweight categories (2.26 in 14.0-18.9, 1.57 in 19.0-20.9, 1.33 in 21.0-22.9 and 1.38 in 27.0-29.9, 1.97 in 30.0-39.9 in men, 1.94 in 14.0-18.9 and 1.91 in 30.0-39.9 in women) after adjustment for possible confounders and weight change. The U-shaped association did not change after excluding deaths occurring in the first 5 y of follow-up or even after excluding subjects who reported a weight loss of 5 kg or more since 20-y-old, or after stratifying subjects by smoking status.


CONCLUSIONS
Both under- and overweight are important determinants of premature death among the Japanese population.
Tsugane
S
S
Epidemiology and Biostatistics Division, National Cancer Center Research Institute East, Kashiwa, Japan. stsugane@east.ncc.go.jp
Sasaki
S
S
Tsubono
Y
Y
D000328:Adult; D000428:Alcohol Drinking; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002423:Cause of Death; D015331:Cohort Studies; D004522:Educational Status; D015444:Exercise; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009026:Mortality; D012306:Risk; D012907:Smoking