Environmental factors associated with body mass index in a population of Southern France

Study objective Environmental-factor changes may largely be accountable for the dramatic increase of obesity prevalence in industrialized countries. This study investigated the relationships between body mass index (BMI) and various socioeconomic, clinical, behavioural and reproductive factors in a population from Southern France. Methods Using a cross-sectional study, a sample of 3127 current and former salaried workers (1658 men and 1469 women) completed a questionnaire on personal and medical histories, and had a clinical examination including height and weight measurements. Age-adjusted and multiple linear regression analyses were performed. Results The overall prevalence of obesity (BMI greater than or equal to 30 kg/m(2)) was 9.8% and was higher in men than in women (11.1 versus 8.3%). Multivariate analyses showed that in both sexes, low educational level, television watching, low physical activity and ex-smoking habits, were independently associated with a higher BMI. Furthermore, in women, we found independent and positive associations between BMI and the number of naps per week, short sleep duration, daily alcohol consumption, the number of pregnancies, early age at menarche or the non-use of oral contraceptives. Conclusions Our results reveal the complexity that exists between BMI and environmental factors and stress the need to analyse and to handle these factors simultaneously.