RESUMEN
Although the prevalence of obesity is higher in low socioeconomic position (SEP), the relationship between SEP and body mass index (BMI) differs according to gender. The purpose of this study is to investigate the relationships between BMI and SEP according to gender and explore the weight-related behaviors. In a cross-sectional survey, 1646 French adults were weighed and answered a questionnaire about eating behavior (DEBQ), SEP markers, ideal weight perception, physical activity and smoking. Our study showed that BMI was inversely correlated with SEP score in women only, independently of other BMI-associated factors (age, restrained eating, smoking status, TV viewing and physical activity). The SEP gradient was the same in both genders for some weight-related behaviors, such as restrained eating, physical activity and TV viewing, but differs for others, such as smoking and weight consciousness. There was an interaction between the SEP score and the actual BMI on the ideal BMI in women only, thus the difference in ideal body weight according to SEP is mainly due to difference in obese women. Our study concluded that gender differences in the relationship between BMI and SEP could be mainly due to the subjects' perception of weight appropriateness and their weight-related behaviors.