Sociodemographic characteristics associated with underweight and overweight in adults aged 50 years and over (ELSI-Brasil): differences between sexes

The objective were to describe the prevalence of underweight and overweight, assessed by body mass index (BMI), stratified by sex and age group, and to analyze the sociodemographic characteristics associated with BMI in older women and men. This is a cross-sectional analysis of 8,974 participants aged ≥ 50 years from the baseline of the Brazilian Longitudinal Study of Aging (ELSI-Brasil, 2015-2016). BMI was classified as underweight, eutrophy, and overweight according to the participant's age. A multinomial logistic regression model was used, considering the sociodemographic characteristics of women and men. The results showed a higher prevalence of overweight in women compared to men (64.1% vs. 57.3%). In both sexes, the prevalence of underweight was higher in the longest-lived individuals, while overweight was lower. In women, the chance of underweight was higher than the chance of eutrophy in those who were single/widowed/divorced (OR = 1.95; 95%CI: 1.42-2.66) and in those living in rural areas (OR = 1.58; 95%CI: 1.01-2.49), while the chance of being overweight was lower than the chance of being eutrophy in those living in rural areas (OR = 0.78; 95%CI: 0.62-0.97) and in all geographic macro-regions related to the South Region. For men, the chance of being overweight was lower than the chance of being eutrophy among single/widowed/divorced individuals (OR = 0.58; 95%CI: 0.48-0.69). The richest had a lower chance of being underweight (OR = 0.59; 95%CI: 0.38-0.90), as well as a higher chance of being overweight (OR = 1.52; 95%CI: 1.20-1.92). In conclusion, the sociodemographic characteristics associated with BMI differed between the sexes.