Association between body mass index and self-rated health: A Swedish population-based longitudinal study.

Aims: We aimed to investigate (a) the association between body mass index (BMI) and self-rated health (SRH) and (b) BMI's predicted value for SRH within a representative population in the Skaraborg Project. Methods: This was a longitudinal observational study. A random population of 2816 individuals were included in the study between 2002 and 2005, and a representative sample of these individuals were invited consecutively for a follow-up visit between 2012 and 2014. At follow-up, data from 1327 participants were collected concerning anthropometric variables, blood samples and validated questionnaires regarding lifestyle factors. Results: A significant inverse association was observed between BMI and SRH both at baseline and at follow-up, with all p-values for trend being ⩽0.001 in both men and women. This association was observed even after adjusting for confounders such as co-morbidity, age, sex, education, marital status and lifestyle factors. In addition, the longitudinal analyses showed that BMI at baseline was inversely associated with SRH at follow-up in both sexes (odds ratio (OR)=1.1, confidence interval (CI) 1.02-1.16, p=0.017 in men; and OR=1.1, CI 1.04-1.14, p=0.001 in women). These findings remained in participants whose weight increased (p=0.022) or was stable (p=0.004), while it was not seen in individuals who lost weight over the years (p=0.340). Conclusions: SRH is inversely associated with BMI in Swedish men and women. High BMI predicted low SRH from a longitudinal perspective, independent of co-morbidities, except for individuals who lost weight over the years. This knowledge emphasises the importance of an understanding and empathetic attitude towards these individuals.