Abstract Background: According to preceding research on long-term changes of bodyweight after smoking abstention in
America, males gained 4.4 kg of bodyweight and females gained 5.0 kg 10 years after smoking abstention.
There is very little research on the changes in bodyweight at the time of and five years after smoking abstention,
and little research on whether or not the changes of bodyweight abroad can be applied to those in
Japan. Therefore, in order to verify the long-term changes of bodyweight in Japanese males, the changes in
the BMI of the same ex-smokers and smokers over a period of 10 years were investigated. Method: Using the results of periodic heath checkups of male workers, this research extracted the changes
over the years of the BMI of individuals from the ex-smoker and smoker groups for 10 years, and a retrospective
cohort research was conducted. Results: The average BMI value of the ex-smoker group was compared with the BMI of the baseline year (22.16
±3.01 kg/m3) and as a result, BMI continued to increase from the first year to the sixth year after smoking
abstention and, at the 6th year after smoking abstention, it showed its highest values (22.84±3.3 kgm3).
From the 7th year after smoking abstention (22.65±3.33 kg/m3), BMI did not tend to increase. As a result of
the comparison of the baseline of each subject from the ex-smoker group with his or her BMI at the 10th
year, 16 subjects showed higher BMI than the baseline and 14 subjects showed lower ones. Furthermore, compared
with the baseline, the number of subjects who showed lower BMIs at the 10th year after quitting smoking
were larger than that of those who showed lower BMIs at the 5th year. As a result of the comparison of
the average BMI of smoker group in each year with its baseline, it gradually increased from the 5th year,
and it was highest at the 9th year (23.78±3.17 kg/m2) compared with other years of the group. Compared with
its baseline, it had significantly increased. Conclusion: It was revealed that the increase of bodyweight after smoking abstention does not extend over a
long period. On the other hand, the BMI of the smoker group tended to increase from the 5th year. It suggested
that smoking habits cannot be said to be useful for weight maintenance.