Work-Related Factors and Their Influence on Body Mass Index: A Retrospective Cohort Study in the French Tertiary Sector

Background/Objectives: Work environments play a crucial role in shaping lifestyle behaviors that influence body weight, yet the relationship between occupational factors and obesity remains underexplored. This study assessed the impact of work-related conditions on body mass index (BMI) trends in a large cohort of tertiary sector employees in France. Methods: A retrospective observational analysis was conducted using occupational health data from 23,853 employees in Paris. BMI changes were assessed through linear regression models, and associations between occupational exposures (e.g. night work, sedentary roles) and BMI variation were examined. Results: Mean BMI at baseline was 23.5 kg/m2 for women and 24.7 kg/m2 for men, with an average BMI increase of 0.15 kg/m2/year and 0.12 kg/m2/year, respectively (p<0.05). Night work and call center employment were associated with significantly higher BMI increases compared to other roles (0.18 vs. 0.13 kg/m2/year and 0.25 vs. 0.13 kg/m2/year, respectively; p<0.05). BMI progression was inversely correlated with socio-professional category, with employees in lower-status jobs exhibiting greater weight gain (p<0.05). Additionally, workers with overweight or obesity at baseline experienced a greater BMI increase, particularly among night shift employees. Conclusions: Work-related factors, particularly night shifts, sedentary roles and lower occupational status, contribute to BMI increases among tertiary sector employees.