Truncal-to-leg fat ratio and cardiometabolic disease risk factors in US adolescents: NHANES 2003-2006.

BACKGROUND: This study aims to describe patterns of truncal versus peripheral fat deposition measured by truncal-to-leg fat ratio (TLR) in adolescents and examine associations of TLR with cardiometabolic (CMD) risk factors.
METHODS: Data were from 3810 adolescents (12-19 years old) in the National Health and Examination Survey (NHANES) 2003-2006. Body fat was assessed by dual-energy X-ray absorptiometry, and CMD risk factors were determined by blood samples and physical examination. Linear and logistic regressions adjusted for BMI z-score and other covariates were used to examine associations of TLR with CMD risk factors as continuous and dichotomized outcomes, respectively.
RESULTS: Adolescents who were Mexican American, who have lower income, and with obesity had the highest mean TLR (all p < 0.05). In linear regression, increasing TLR was associated positively with homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, total cholesterol, systolic blood pressure (BP), c-reactive protein, and alanine aminotransferase (ALT), and negatively with high-density lipoprotein (HDL) cholesterol in both sexes (p < 0.05). TLR was also associated with diastolic BP in boys and low-density lipoprotein cholesterol in girls (p < 0.05). A similar pattern of findings resulted from logistic regression. When further stratified by race/ethnicity, TLR was positively associated with high triglycerides, total cholesterol, and ALT for White and/or Mexican American (p < 0.05), but not Black adolescents, while associations with HOMA-IR and HDL were significant for all race/ethnicities.
CONCLUSIONS: In this cohort of adolescents, TLR was associated with several risk factors independent of BMI z-score, although some findings were sex or race/ethnicity specific. Body fat distribution may be an important determinant of future CMD.