Long-period Accelerometer Monitoring Shows the Role of Physical Activity in Overweight and Obesity

Context: Physical activity (PA) plays an important role in obesity. A new accelerometer has been developed to assess total energy expenditure as well as PA.

Objective: To investigate the association of PA with overweight and obesity in Japanese men and women, a large cross-sectional study was performed using a single-axis accelerometer.

Design, Setting And Participants: Population-based cross-sectional study of Japanese 18-84 y of age. Height, body weight and PA were measured in 400 male and 388 female Japanese volunteers from 1999 to 2000. The outcome measurements were overweight and obesity, which are defined as a body mass index >/=25 kg/m(2). PA was measured for 1 to 4 weeks and was then categorized into three activity levels, which were defined as light, moderate and vigorous PA.

Results: Prevalence of overweight and obesity was 22.3%. Number of steps and time spent in moderate and vigorous PA per day were lower in overweight and obese individuals. No difference was found in time spent in light PA. Individuals who are in the 4th and 5th quintile of moderate and vigorous PA showed a significantly lower body mass index. When odd ratios (ORs) of overweight and obesity estimated by logistic regression were used as effect measures, overweight and obesity were negatively associated with vigorous PA (ORs=0.91).

Conclusion: These results indicate that overweight and obese individuals have a lower step rate and are spending less time for moderate to vigorous PA. Participation in vigorous PA is an important predictor of overweight and obesity.