Association between children and adolescents’ body composition with family income

Abstract

Objective To evaluate the association between children and adolescents’ body composition with family income. Methods Cross-sectional study, participants between 5 and 19 years were included. A standardized questionnaire assessed socioeconomic variables. The outcome variables were z-score of Body Mass Index and bioimpedance parameters (skeletal muscle mass, fat-free mass, and fat percentage) and predictor variables (age, sex, race, place of residence, father’s education, birth weight and breastfeeding) were analyzed using the quantile regression model and data from the 50th percentile are presented. The tests were bidirectional and the differences were considered significant with p<0.05. Results Among the 529 participants included, 284 (53.6%) were female and the mean age was 11.41±3.9 years. The Body Mass Index z-score was the only outcome that did not show differences between sexes (p=0.158). In the crude model, lower family income was associated with lower skeletal muscle mass (Difference=-7.70; 95% CI -9.32 to -5.89), p<0.001), lower fat-free mass (Difference= -13.40; 95% CI -16.40 to -10.39, p<0.001) and the lowest percentage of fat was associated with lower family income (Difference= -5.01, 95% CI -9.91 to -0.11, p=0.027). The z-score of BMI was not associated with family income. Conclusion Family income is directly associated with lower fat-free mass, fat percentage, and skeletal muscle mass in children and adolescents.