The influence of social relationships on obesity: sex differences in a longitudinal study.

Objective: To investigate the effect of five dimensions of social relationships on obesity and potential sex differences in these associations.

Design And Methods: This study used longitudinal data from the Swedish Level of Living Surveys (LNU) in 1991 and 2000. The sample included 3,586 individuals. The dimensions of social relationships examined in this study include emotional support, frequency of visiting friends, marital status, marital status changes, and a Social Relationships Index (SRI). Obesity status was based on BMI (kg/m(2)) and calculated with self-reported measurements. The association between social relationships and the incidence of obesity after 9 years of follow-up was evaluated through Poisson regressions.

Results: After controlling for confounders, we found that the lack of emotional support (RR = 1.98; 95% CI, 1.1-4.6) influenced the incidence of obesity among men. In addition, men with the lowest levels of SRI (RR = 2.22; 95% CI, 1.1-4.4) had an increased risk of being obese. Among women, SRI was not significantly associated with obesity. Women who changed their marital status from married to unmarried had lower risk of obesity (RR = 0.39; 95% CI, 0.2-0.9).

Conclusions: This study provides evidence for the effect of social relationships on the incidence of obesity, with significant differences by sex.