|| The purpose of this study was to clarify, through a prospective study, the relationship between leptin and adiponectin levels, and subsequent weight change. The study subjects were 2,485 male office workers aged 35-64 employed by a company in Fukuoka Prefecture, Japan. Of these men, 1,936
(77.9%) received health check-ups both in 2005-2007 and 3 years later, in 2008-2010. Of the subjects who received both health check-ups, 352 were excluded duo to cancer, cardiac infarction, stroke or diabetes mellitus, leaving a total of 1,584. We divided them into tertiles according to baseline leptin and adiponectin levels, and compared the subsequent change in body mass index (BMI) over 3 years. The subjects with the lowest leptin levels showed a significantly greater increase in BMI (difference in change in BMI＝0.178kg/m2, 95% CI:0.025-0.331kg/m2) over 3 years when those with the highest leptin levels were regarded as the reference even after adjusting for age, baseline BMI, smoking status, drinking status and exercise. The subjects with the highest adiponectin levels showed a greater increase in BMI (difference in change in BMI＝0.099kg/m2, 95% CI:－0.034-0.231kg/m2) over 3 years when those with the lowest adiponectin levels were regarded as the reference, but this association was not statistically significant after adjusting for age, baseline BMI, smoking status, drinking status and exercise. Our findings suggest that higher leptin levels may suppress weight gain in Japanese male workers.