Objective: Limited data are available regarding longitudinal changes in body weight. Here, we describe changes in the prevalences of overweight and obesity and calculated the incidence of these indices during a 10-year follow-up period for a large-scale cohort study in Japan.
Design: Longitudinal analysis of data from a population-based cohort study, the Japan Public Health Center (JPHC) Study.
Participants: A total of 65 095 Japanese men and women, who were between the ages of 40 and 69 years at baseline and participated in the 5th- and 10th-year follow-up surveys of the JPHC, were enroled in the study.
Measurements: Mean body mass index (BMI), calculated using self-reported height and weight, and the prevalences of overweight (BMI >or=25 kg/m(2)) and obesity (BMI >or=30 kg/m(2)) at each survey period. Incidences of overweight and obesity during the 10-year period.
Results: On an average, individuals living in Okinawa had much higher BMIs than those living on the Main islands for all sex and age groups. During the follow-up period, the prevalences of overweight and obesity steadily increased in the cohorts aged less than 50 years at baseline in both sexes. Men in younger cohorts had a higher mean BMI than those in the same age group of older cohorts, whereas the opposite trend was observed in women. The incidence of overweight individuals was greater in Okinawa than on the Main islands and among younger generations than among older ones.
Conclusion: A longitudinal analysis at the individual level showed that the prevalences of overweight and obesity increased among middle-aged Japanese participants during the follow-up period. Among men, an increasing prevalence of obesity was observed among the younger generations. These findings should be taken into consideration when planning preventive strategies for obesity and its related diseases.