Impact of changes in commuting mode on body weight among Japanese workers: a longitudinal study.

Objective: The health benefits of active commuting have been reported. However, few studies have assessed commuting modes using objective methods. This study clarified the association between changes in objectively measured commuting modes and body weight among Japanese workers.

Methods: This longitudinal study used data from the annual health examinations and personnel records of a company with branches in all prefectures of Japan. Data from 2018 and 2019 were used as the baseline and follow-up data, respectively. The commuting mode was assessed using the commuting mode code included in the personnel records and classified into 3 types: walking, public transport, and car or motorcycle. The participants were classified into 9 categories based on the combination of their commuting modes in 2018 and 2019. Body weight was measured objectively during health examinations. The 1-year changes in body weight were calculated for the 9 categories and assessed using an analysis of covariance with adjustments for covariates.

Results: The analysis included 6551 workers (men: 86.8%; mean age: 42.8 years). Overall, body weights tended to increase (+0.40 kg/y). The participants who switched to more active commuting, such as from car or motorcycle to walking (-0.13 kg/y), from car or motorcycle to public transport (+0.10 kg/y), and from public transport to walking (-0.07 kg/y), exhibited small weight gains or losses. A similar trend was observed even after adjustment.

Conclusions: Changing to a more active commuting mode may prevent weight gain among workers.