Background: Obesity and weight gain are associated with increased risk of coronary heart disease in Western countries. However, their impact is not well elucidated in Asia, where body mass index (BMI) levels are generally lower than in Western countries. We examined associations of BMI (kg/m(2)) and weight change with risk of coronary heart disease in Japanese people.
Methods and results: A total of 43 235 men and 47 444 women aged 40-69 years living in communities were followed up from 1990 to 2001 in the Japan Public Health Center-based (JPHC) prospective study . During 879 619 person-years of follow-up, we documented 399 cases of coronary heart disease (334 myocardial infarction and 65 sudden cardiac death) for men and 119 (95 myocardial infarction and 24 sudden cardiac death) for women. Compared with persons with BMI 23.0-24.9, men, but not women, with BMI >/=30.0 had higher risk of coronary heart disease and myocardial infarction; the multivariable relative risks for men were 1.8 (1.1-3.0) and 1.9 (1.1-3.2), respectively. When weight change was examined according to BMI at age 20 years, men with initial BMI <21.7 who gained more than 10 kg compared with men of no weight change had a twofold higher risk of coronary heart disease. Both men and women with initial BMI >/=21.7 showed no association between weight loss and the risk.
Conclusions: High BMI was associated with increased risk of coronary heart disease among men. Also, weight gain was associated with increased risk among lean men.