Sedentary work-Associations between five-year changes in occupational sitting time and body mass index

•Data from The Danish Work Environment Cohort from 2005 to 2010 was analyzed.•Association between five-year changes in occupational sitting and BMI was explored.•43.0% men and 36.1% women had high occupational sitting time (≥ 25 h/week).•The proportion of obese (BMI ≥ 30) increased almost 3% for both genders.•In women, BMI increased 0.13 (p = 0.0003), per category of occupational sitting.

ObjectiveThe aim of this study is to investigate the association between five-year changes in occupational sitting and body mass index (BMI) in working adults.MethodsWe analyzed data from The Danish Work Environment Cohort Study (2005 and 2010, n = 3.482). Data on occupational sitting, weight, height and several potential confounders were self-reported. The association between change in occupational sitting (hours) (categorized as large decrease < − 7.5, moderate decrease − 7.5 to < − 2.5, no change − 2.5 to 2.5, moderate increase > 2.5 to 7.5 and large increase > 7.5) and change in BMI was explored by multiple linear regression analyses.Results43.0% men and 36.1% women had high occupational sitting time (≥ 25 h per week) at baseline. 31.8% men and 27.2% women decreased while 30.0% men and 33.0% women increased occupational sitting. The proportion of obese (BMI ≥ 30) increased almost 3% for both genders. BMI changed 0.13 (CI: 0.06; 0.20, p = 0.0003), per category of change in occupational sitting in women, but no association was found in men.ConclusionIn women, there is a positive association between five-year changes in occupational sitting and BMI.